MEDIACTRL A. Amirante Internet-Draft T. Castaldi Expires: September 5, 2009 L. Miniero S P. Romano University of Napoli March 4, 2009 Media Control Channel Framework (CFW) Call Flow Examples draft-ietf-mediactrl-call-flows-00 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 5, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document provides a list of typical Media Control Channel Amirante, et al. Expires September 5, 2009 [Page 1] Internet-Draft CFW Call Flow Examples March 2009 Framework [I-D.ietf-mediactrl-sip-control-framework] call flows. It aims at being a simple guide to the use of the interface between Application Servers and MEDIACTRL-based Media Servers, as well as a base reference documentation for both implementors and protocol researchers. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. A Practical Approach . . . . . . . . . . . . . . . . . . . . 4 4.1. State Diagrams . . . . . . . . . . . . . . . . . . . . . 5 5. Control Channel Establishment . . . . . . . . . . . . . . . . 8 5.1. COMEDIA Negotiation . . . . . . . . . . . . . . . . . . . 9 5.2. SYNC . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6. Use-case scenarios and examples . . . . . . . . . . . . . . . 14 6.1. Echo Test . . . . . . . . . . . . . . . . . . . . . . . . 21 6.1.1. Direct Echo Test . . . . . . . . . . . . . . . . . . 22 6.1.2. Echo Test based on Recording . . . . . . . . . . . . 24 6.2. Phone Call . . . . . . . . . . . . . . . . . . . . . . . 32 6.2.1. Direct Connection . . . . . . . . . . . . . . . . . . 34 6.2.2. Conference-based Approach . . . . . . . . . . . . . . 36 6.2.3. Recording a conversation . . . . . . . . . . . . . . 42 6.3. Conferencing . . . . . . . . . . . . . . . . . . . . . . 49 6.3.1. Simple Bridging . . . . . . . . . . . . . . . . . . . 53 6.3.2. Rich Conference Scenario . . . . . . . . . . . . . . 58 6.3.3. Conferencing with Floor Control . . . . . . . . . . . 68 6.3.4. Coaching Scenario . . . . . . . . . . . . . . . . . . 69 6.3.5. Sidebars . . . . . . . . . . . . . . . . . . . . . . 76 6.4. Additional Scenarios . . . . . . . . . . . . . . . . . . 77 6.4.1. Voice Mail . . . . . . . . . . . . . . . . . . . . . 77 6.4.2. Current Time . . . . . . . . . . . . . . . . . . . . 85 6.4.3. DTMF-driven Conference Manipulation . . . . . . . . . 89 7. Security Considerations . . . . . . . . . . . . . . . . . . . 102 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 102 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 102 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 104 Amirante, et al. Expires September 5, 2009 [Page 2] Internet-Draft CFW Call Flow Examples March 2009 1. Introduction This document provides a list of typical MEDIACTRL Media Control Channel Framework [I-D.ietf-mediactrl-sip-control-framework] call flows. The motivation for this comes from our implementation experience with the framework and its protocol. This drove us to writing a simple guide to the use of the several interfaces between Application Servers and MEDIACTRL-based Media Servers and a base reference documentation for other implementors and protocol researchers. Following this spirit, this document covers several aspects of the interaction between Application Servers and Media Servers. However, in the context of this document, the call flows almost always depict the interaction between a single Application Server (which, for the sake of conciseness, is called AS from now on) and a single Media Server (MS). To ease the understanding of all the flows (for what concerns both SIP dialogs and CFW transactions), the domains hosting the AS and the MS in all the scenarios are called, respectively, 'cicciopernacchio.com' and 'pippozzoserver.org'. In the next paragraphs a brief overview of our implementation approach is described, with particular focus on protocol-related aspects. This involves state diagrams for what concerns both the client side (the AS) and the server side (the MS). Of course, this section is not at all to be considered a mandatory approach to the implementation of the framework. It is only meant to ease the understanding of how the framework works from a practical point of view. Once done with these preliminary considerations, in the subsequent sections real-life scenarios are faced. In this context, first of all, the establishment of the Control Channel is dealt with: after that, some use case scenarios, involving the most typical multimedia applications, are depicted and described. It is worth pointing out that this document is not meant in any way to be a self-sustained guide to implementing a MEDIACTRL-compliant framework. The specifications are a mandatory read for all implementors, especially considering that this document by itself follows their guidelines but does not delve into the details of every aspect of the protocol. 2. Conventions In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT Amirante, et al. Expires September 5, 2009 [Page 3] Internet-Draft CFW Call Flow Examples March 2009 RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 [RFC2119] and indicate requirement levels for compliant implementations. Besides, note that due to RFC formatting conventions, this document often splits SIP/SDP and CFW across lines whose content would exceed 72 characters. A backslash character marks where this line folding has taken place. This backslash and its trailing CRLF and whitespace would not appear in the actual protocol contents. 3. Terminology This document makes use of the same terminology as the one that can be found in the referenced documents. The following terms are only a summarization of the most commonly used ones in this context, mostly derived from the terminology used in the related documents: Application Server: an entity that requests media processing and manipulation from a Media Server; typical examples are Back to Back User Agents (B2BUA) and endpoints requesting manipulation of a third-party's media stream. Media Server: an entity that performs a service, such as media processing, on behalf of an Application Server; typical provided functions are mixing, announcement, tone detection and generation, and play and record services. Control Channel: a reliable connection between an Application Server and a Media Server that is used to exchange Framework messages. 4. A Practical Approach In this document we embrace an engineering approach to the description of a number of interesting scenarios that can be realized through the careful orchestration of the Media Control Channel Framework entities, namely the Application Server and the Media Server. We will demonstrate, through detailed call flows, how a variegated bouquet of services (ranging from very simple scenarios to much more complicated ones) can be implemented with the functionality currently offered, within the main MEDIACTRL framework, by the control packages that have been made available to date. The document aims at representing a useful guide for those interested in investigating the inter-operation among MEDIACTRL components, as well as for application developers willing to build advanced services on top of the base infrastructure made available by the framework. Amirante, et al. Expires September 5, 2009 [Page 4] Internet-Draft CFW Call Flow Examples March 2009 4.1. State Diagrams In this section we present an "informal" view of the main MEDIACTRL protocol interactions, in the form of state diagrams. Each diagram is indeed a classical representation of a Mealy automaton, comprising a number of possible protocol states, indicated with rectangular boxes. Transitions between states are indicated through edges, with each edge labeled with a slash-separated pair representing a specific input together with the associated output (a dash in the output position means that, for that particular input, no output is generated from the automaton). Some of the inputs are associated with MEDIACTRL protocol messages arriving at a MEDIACTRL component while it is in a certain state: this is the case of 'CONTROL', 'REPORT' (in its various "flavors" -- pending, terminate, etc.), '200', '202', as well as 'Error'. Further inputs represent triggers arriving at the MEDIACTRL automaton from the upper layer, namely the Application Programming Interface used by programmers while implementing MEDIACTRL-enabled services: such inputs have been indicated with the term 'API' followed by the message that the API itself is triggering (as an example, 'API terminate' is a request to send a 'REPORT' message with a status of 'terminate' to the peering component). Four diagrams are provided, which can be divided in two main categories, associated, respectively, with normal operation of the framework (Figure 1 and Figure 2) and with asynchronous event notifications (Figure 3). As to the former category, in Figure 1 we embrace the MS perspective, whereas in Figure 2 we stand on the AS side. The latter category is dealt with in Figure 3, which illustrates how notifications are managed. In particular, the upper part of the figure shows how events are generated, on the MS side, by issuing a CONTROL message addressed to the AS; events are acknowledged by the AS through standard 200 responses. Hence, the behavior of the AS, which mirrors that of the MS, is depicted in the lower part of the picture. Coming back to Figure 1, the diagram shows that the MS activates upon reception of CONTROL messages coming from the AS, which typically instruct it about the execution of a specific command, belonging to one of the available control packages. The execution of the received command can either be quick, or require some time. In the former case, right after completing its operation, the MS sends back to the AS a 200 message, which basically acknowledges correct termination of the invoked task. In the latter case, the MS first sends back an interlocutory 202 message, which lets it enter a different state ('202' sent). While in the new state, the MS keeps on performing the invoked task: if such task does not complete in a predefined timeout, the server will update the AS on the other side of the control channel by periodically issuing 'REPORT/update' messages; each such message has to be acknowledged by the AS (through a '200' response). Eventually, when the MS is done with the required service, it sends to the AS a 'REPORT/terminate' Amirante, et al. Expires September 5, 2009 [Page 5] Internet-Draft CFW Call Flow Examples March 2009 message, whose acknowledgment receipt concludes a transaction. Again, the AS behavior, depicted in Figure 2, mirrors the above described actions undertaken at the MS side. Figures also show the cases in which transactions cannot be successfully completed due to abnormal conditions, which always trigger the creation and expedition of a specific 'Error' message. +------------------+ CONTROL/- +------------------+ API 202/202 | Idle/'terminate' |------------>| CONTROL received |---------+ +------------------+ +------------------+ | ^ ^ ^ API 200/200 | | | | | | | | | | | +------------------+ | | | 200/- | API Error/Error | | | +----------------------------+ | | | +-------------+ | | Waiting for | v | last 200 |<------------------------+ +------------+ +-------------+ | | '202' sent | ^ | +------------+ | | | | | +---------------+ | | API terminate/ API terminate/ | | REPORT terminate REPORT termnate | | | +--------------------+ | | 'update' confirmed |------+ API update/ | +--------------------+ | REPORT update | ^ | API update/ | | | REPORT update | | v | | 200/- +---------------+ | +--------------| 'update' sent |<----------------+ +---------------+ Figure 1: Media Server CFW State Diagram Amirante, et al. Expires September 5, 2009 [Page 6] Internet-Draft CFW Call Flow Examples March 2009 +--------------+ 202/- +--------------+ +-->| CONTROL sent |---------->| 202 received | | +--------------+ +--------------+ | | | | | | | | | | API CONTROL/ | | 200/- | | | send CONTROL | | | | | | | | Error/ | | +------------------+ | | Error | | | Idle/'terminate' |<-+ | | | +------------------+<---------+ | | ^ ^ | | | | REPORT 'terminate'/ | | | | send 200 | | | +--------------------------------+ | REPORT 'update'/ | | send 200 | REPORT 'terminate'/ | | send 200 | | +-----------+ | +---------------------| 'update ' |<--------------+ +-----------+ ^ | | | REPORT 'update'/ +------+ send 200 Figure 2: Application Server CFW State Diagram Amirante, et al. Expires September 5, 2009 [Page 7] Internet-Draft CFW Call Flow Examples March 2009 +--------------+ +-->| CONTROL sent | | +--------------+ | | | | API CONTROL/ | | 200/- send CONTROL | | | | +------------------+ | | Idle/'terminate' |<----+ +------------------+ (Media Server perspective) +------------------+ CONTROL/- +------------------+ | Idle/'terminate' |------------>| CONTROL received | +------------------+ +------------------+ ^ API 200/200 | | | +----------------------------+ (Application Server perspective) Figure 3: Event Notifications 5. Control Channel Establishment As specified in [I-D.ietf-mediactrl-sip-control-framework], the preliminary step to any interaction between an AS and a MS is the establishment of a control channel between the two. As explained in the next subsection, this is accomplished by means of a so-called COMEDIA [RFC4145] negotiation. This negotiation allows for a reliable connection to be created between the AS and the MS: it is here that the AS and the MS agree on the transport level protocol to use (TCP/SCTP) and whether any application level security is needed or not (e.g. TLS). For the sake of simplicity, we assume that an unencrypted TCP connection is negotiated between the two involved entities. Once they have connected, a SYNC message sent by the AS to the MS consolidates the control channel. Amirante, et al. Expires September 5, 2009 [Page 8] Internet-Draft CFW Call Flow Examples March 2009 AS MS | | | INVITE (COMEDIA) | |------------------------------>| | 100 (Trying) | |<------------------------------| | 200 OK (COMEDIA) | |<------------------------------| | ACK | |------------------------------>| | | |==============================>| | TCP CONNECT (CTRL CHANNEL) | |==============================>| | | | SYNC (Dialog-ID, etc.) | |+++++++++++++++++++++++++++++>>| | |--+ | | | Check SYNC | |<-+ | 200 OK | |<<+++++++++++++++++++++++++++++| | | . . . . Figure 4: Control Channel Establishment 5.1. COMEDIA Negotiation As a first step, the AS and the MS establish a Control SIP dialog. This is usually originated by the AS itself. The AS generates a SIP INVITE message containing in its SDP body information about the TCP connection it wants to establish with the MS. In the provided example (see Figure 5 and the attached call flow), the AS wants to actively open a new TCP connection, which on his side will be bound to port 5757. If the request is fine, the MS answers with its own offer, by communicating to the AS the transport address to connect to in order to establish the TCP connection. In the provided example, the MS will listen on port 7575. Once this negotiation is over, the AS can effectively connect to the MS. The negotiation includes additional attributes, the most important being the 'cfw-id' attribute, since it specifies the Dialog-ID which will be subsequently referred to by both the AS and the MS, as specified in the core framework draft. Amirante, et al. Expires September 5, 2009 [Page 9] Internet-Draft CFW Call Flow Examples March 2009 Note that the provided example also includes the indication, from both the AS and the MS, of the supported control packages. This is achieved by means of a series of 'ctrl-package' attributes as specified in [I-D.boulton-mmusic-sdp-control-package-attribute]. In the example, the AS supports (or is only interested to) two packages: IVR (Interactive Voice Response) and Mixer (Conferencing and Bridging). The MS replies with the list of packages it supports, by adding a dummy example package to the list provided by the AS. It is worth noting that this exchange of information is not meant as a strict or formal negotiation of packages: in case the AS realizes that one or more packages it needs are not supported according to the indications sent by the MS, it may, or may not, choose not to open a control channel with the MS at all, if its application logic leads to such a decision. The actual negotiation of control packages is done subsequenty through the use of the framework SYNC transaction. [Editors Note: the SDP ctrl-package attribute draft recently expired, and so these attributes would actually not appear in the negotiation. However, they have some use. Is the draft going to be refreshed or is the WG not interested in such a work?] AS MS | | | 1. INVITE (COMEDIA) | |------------------------------>| | 2. 100 (Trying) | |<------------------------------| | 3. 200 OK (COMEDIA) | |<------------------------------| | 4. ACK | |------------------------------>| | | |==============================>| | TCP CONNECT (CTRL CHANNEL) | |==============================>| | | . . . . Figure 5: COMEDIA Negotiation: Sequence Diagram 1. AS -> MS (SIP INVITE) ------------------------ Amirante, et al. Expires September 5, 2009 [Page 10] Internet-Draft CFW Call Flow Examples March 2009 INVITE sip:MediaServer@pippozzoserver.org:5060 SIP/2.0 Via: SIP/2.0/UDP 1.2.3.4:5060;\ branch=z9hG4bK-d8754z-9b07c8201c3aa510-1---d8754z-;rport=5060 Max-Forwards: 70 Contact: To: From: ;tag=4354ec63 Call-ID: MDk2YTk1MDU3YmVkZjgzYTQwYmJlNjE5NTA4ZDQ1OGY. CSeq: 1 INVITE Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, UPDATE, REGISTER Content-Type: application/sdp Content-Length: 263 v=0 o=lminiero 2890844526 2890842807 IN IP4 cicciopernacchio.com s=MediaCtrl c=IN IP4 cicciopernacchio.com t=0 0 m=application 5757 TCP/CFW * a=connection:new a=setup:active a=cfw-id:5feb6486792a a=ctrl-package:msc-ivr/1.0 a=ctrl-package:msc-mixer/1.0 2. AS <- MS (SIP 100 Trying) ---------------------------- SIP/2.0 100 Trying Via: SIP/2.0/UDP 1.2.3.4:5060; \ branch=z9hG4bK-d8754z-9b07c8201c3aa510-1---d8754z-;rport=5060 To: ;tag=499a5b74 From: ;tag=4354ec63 Call-ID: MDk2YTk1MDU3YmVkZjgzYTQwYmJlNjE5NTA4ZDQ1OGY. CSeq: 1 INVITE Content-Length: 0 3. AS <- MS (SIP 200 OK) ------------------------ SIP/2.0 200 OK Via: SIP/2.0/UDP 1.2.3.4:5060; \ branch=z9hG4bK-d8754z-9b07c8201c3aa510-1---d8754z-;rport=5060 Contact: To: ;tag=499a5b74 From: ;tag=4354ec63 Call-ID: MDk2YTk1MDU3YmVkZjgzYTQwYmJlNjE5NTA4ZDQ1OGY. CSeq: 1 INVITE Amirante, et al. Expires September 5, 2009 [Page 11] Internet-Draft CFW Call Flow Examples March 2009 Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, UPDATE, REGISTER Content-Type: application/sdp Content-Length: 296 v=0 o=lminiero 2890844526 2890842808 IN IP4 pippozzoserver.org s=MediaCtrl c=IN IP4 pippozzoserver.org t=0 0 m=application 7575 TCP/CFW * a=connection:new a=setup:passive a=cfw-id:5feb6486792a a=ctrl-package:msc-ivr/1.0 a=ctrl-package:msc-example-pkg/1.0 a=ctrl-package:msc-mixer/1.0 4. AS -> MS (SIP ACK) --------------------- ACK sip:MediaServer@pippozzoserver.org:5060 SIP/2.0 Via: SIP/2.0/UDP 1.2.3.4:5060; \ branch=z9hG4bK-d8754z-22940f5f4589701b-1---d8754z-;rport Max-Forwards: 70 Contact: To: ;tag=499a5b74 From: ;tag=4354ec63 Call-ID: MDk2YTk1MDU3YmVkZjgzYTQwYmJlNjE5NTA4ZDQ1OGY. CSeq: 1 ACK Content-Length: 0 5.2. SYNC Once the AS and the MS have successfully established a TCP connection, an additional step is needed before the control channel can be used. In fact, as seen in the previous subsection, the first interaction between the AS and the MS happens by means of a SIP dialog, which in turns allows for the creation of the TCP connection. This introduces the need for a proper correlation between the above mentioned entities (SIP dialog and TCP connection), so that the MS can be sure the connection came from the AS which requested it. This is accomplished by means of a dedicated framework message called SYNC. This SYNC message makes use of a unique identifier called Dialog-ID to validate the control channel. This identifier, as introduced in the previous paragrah, is meant to be globally unique and as such is properly generated by the caller (the AS in the call flow), and added as an SDP media attribute (cfw-id) to the COMEDIA Amirante, et al. Expires September 5, 2009 [Page 12] Internet-Draft CFW Call Flow Examples March 2009 negotiation in order to make both entities aware of its value: a=cfw-id:5feb6486792a ^^^^^^^^^^^^ Besides, it offers an additional negotiation mechanism. In fact, the AS uses the SYNC not only to properly correlate as explained before, but also to negotiate with the MS the control packages it is interested in, as well as to agree on a Keep-Alive timer needed by both the AS and the MS to understand if problems on the connection occur. In the provided example (see Figure 6 and the related call flow), the AS sends a SYNC with a Dialog-ID constructed as needed (using the 'cfw-id' attribute from the SIP dialog) and requests access to two control packages, specifically the IVR and the Mixer package (the same packages the AS previously indicated in its SDP as specified in [I-D.boulton-mmusic-sdp-control-package-attribute], with the difference that this time they are reported in the context of a binding negotiation). Besides, it instructs the MS that a 100 seconds timeout is to be used for Keep-Alive messages. The MS validates the request by matching the received Dialog-ID with the SIP dialog values and, assuming it supports the control packages the AS requested access to (and for the sake of this document we assume it does), it answers with a 200 message. Additionally, the MS provides the AS with a list of other unrequested packages it supports (in this case just a dummy package providing testing functionality). AS MS . . . . | | | 1. SYNC (Dialog-ID, etc.) | |+++++++++++++++++++++++++++++>>| | |--+ | | | Check SYNC | |<-+ | 2. 200 OK | |<<+++++++++++++++++++++++++++++| | | . . . . Figure 6: SYNC: Sequence Diagram Amirante, et al. Expires September 5, 2009 [Page 13] Internet-Draft CFW Call Flow Examples March 2009 1. AS -> MS (CFW SYNC) ---------------------- CFW 6e5e86f95609 SYNC Dialog-ID: 5feb6486792a Keep-Alive: 100 Packages: msc-ivr/1.0,msc-mixer/1.0 2. AS <- MS (CFW 200) --------------------- CFW 6e5e86f95609 200 Keep-Alive: 100 Packages: msc-ivr/1.0,msc-mixer/1.0 Supported: msc-example-pkg/1.0 The framework level transaction identifier is obviously the same in both the request and the response (6e5e86f95609), since the AS needs to be able to match the response to the original request. At this point, the control channel is finally established, and it can be used by the AS to request services from the MS. 6. Use-case scenarios and examples The following scenarios have been chosen for their common presence in many rich real-time multimedia applications. Each scenario is depicted as a set of call flows, involving both the SIP/SDP signaling (UACs<->AS<->MS) and the Control Channel communication (AS<->MS). All the examples assume that a Control Channel has already been correctly established and SYNCed between the reference AS and MS. Besides, unless stated otherwise, the same UAC session is referenced in all the above mentioned examples. The UAC session is assumed to have been created as the described Figure 7: Amirante, et al. Expires September 5, 2009 [Page 14] Internet-Draft CFW Call Flow Examples March 2009 UAC AS MS | | | | INVITE (X) | | |------------------>| | | 180 (Ringing) | | |<------------------| | | |--+ | | | | Handle app(X) | | |<-+ | | | INVITE (X) as 3PCC | | |-------------------------->| | | 100 (Trying) | | |<--------------------------| | | |--+ Negotiate media | | | | with UAC and map | | |<-+ tags and labels | | 200 OK | | |<--------------------------| | 200 OK | | |<------------------| | | ACK | | |------------------>| | | | ACK | | |-------------------------->| | | | |<<###########################################>>| | RTP Media Stream(s) flowing | |<<###########################################>>| | | | . . . . . . Figure 7: 3PCC Sequence Diagram Note well: this is only an example of a possible approach involving a 3PCC negotiation among the UAC, the AS and the MS, and as such is not at all to be considered as the mandatory way or as best common practice either in the presented scenario. [RFC3725] provides several different solutions and many details about how 3PCC can be realized, with pros and cons. The UAC first places a call to a SIP URI the AS is responsible of. The specific URI is not relevant to the examples, since the application logic behind the mapping between a URI and the service it provides is a matter that is important only to the AS: so, a generic 'sip:mediactrlDemo@cicciopernacchio.com' is used in all the examples, whereas the service this URI is associated with in the AS logic is Amirante, et al. Expires September 5, 2009 [Page 15] Internet-Draft CFW Call Flow Examples March 2009 mapped scenario by scenario to the case under exam. The UAC INVITE is treated as envisaged in [I-D.ietf-mediactrl-architecture]: the INVITE is forwarded by the AS to the MS in a 3PCC fashion, without the SDP provided by the UAC being touched, so to have the session fully negotiated by the MS for what concerns its description. The MS matches the UAC's offer with its own capabilities and provides its answer in a 200 OK. This answer is then forwarded, again without the SDP contents being touched, by the AS to the UAC it is intended for. This way, while the SIP signaling from the UAC is terminated in the AS, all the media would start flowing directly between the UAC and the MS. As a consequence of this negotiation, one or more media connections are created between the MS and the UAC. They are then addressed, when needed, by the AS and the MS by means of the tags concatenation as specified in [I-D.ietf-mediactrl-sip-control-framework]. How the identifiers are created and addressed is explained by making use of the sample signaling provided in Figure 8. 1. UAC -> AS (SIP INVITE) ------------------------- INVITE sip:mediactrlDemo@cicciopernacchio.com SIP/2.0 Via: SIP/2.0/UDP 4.3.2.1:5063;rport;branch=z9hG4bK1396873708 From: ;tag=1153573888 To: Call-ID: 1355333098 CSeq: 20 INVITE Contact: Content-Type: application/sdp Max-Forwards: 70 User-Agent: Linphone/2.1.1 (eXosip2/3.0.3) Subject: Phone call Expires: 120 Content-Length: 330 v=0 o=lminiero 123456 654321 IN IP4 4.3.2.1 s=A conversation c=IN IP4 4.3.2.1 t=0 0 m=audio 7078 RTP/AVP 0 3 8 101 a=rtpmap:0 PCMU/8000/1 a=rtpmap:3 GSM/8000/1 a=rtpmap:8 PCMA/8000/1 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-11 Amirante, et al. Expires September 5, 2009 [Page 16] Internet-Draft CFW Call Flow Examples March 2009 m=video 9078 RTP/AVP 98 a=rtpmap:98 H263-1998/90000 a=fmtp:98 CIF=1;QCIF=1 2. UAC <- AS (SIP 180 Ringing) ------------------------------ SIP/2.0 180 Ringing Via: SIP/2.0/UDP 4.3.2.1:5063;rport=5063; \ branch=z9hG4bK1396873708 Contact: To: ;tag=bcd47c32 From: ;tag=1153573888 Call-ID: 1355333098 CSeq: 20 INVITE Content-Length: 0 3. AS -> MS (SIP INVITE) ------------------------ INVITE sip:MediaServer@pippozzoserver.org:5060;transport=UDP SIP/2.0 Via: SIP/2.0/UDP 1.2.3.4:5060; \ branch=z9hG4bK-d8754z-8723e421ebc45f6b-1---d8754z-;rport Max-Forwards: 70 Contact: To: From: ;tag=10514b7f Call-ID: NzI0ZjQ0ZTBlMTEzMGU1ZjVhMjk5NTliMmJmZjE0NDQ. CSeq: 1 INVITE Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, UPDATE, REGISTER Content-Type: application/sdp Content-Length: 330 v=0 o=lminiero 123456 654321 IN IP4 4.3.2.1 s=A conversation c=IN IP4 4.3.2.1 t=0 0 m=audio 7078 RTP/AVP 0 3 8 101 a=rtpmap:0 PCMU/8000/1 a=rtpmap:3 GSM/8000/1 a=rtpmap:8 PCMA/8000/1 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-11 m=video 9078 RTP/AVP 98 a=rtpmap:98 H263-1998/90000 a=fmtp:98 CIF=1;QCIF=1 Amirante, et al. Expires September 5, 2009 [Page 17] Internet-Draft CFW Call Flow Examples March 2009 4. AS <- MS (SIP 100 Trying) ---------------------------- SIP/2.0 100 Trying Via: SIP/2.0/UDP 1.2.3.4:5060; \ branch=z9hG4bK-d8754z-8723e421ebc45f6b-1---d8754z-;rport=5060 To: ;tag=6a900179 From: ;tag=10514b7f Call-ID: NzI0ZjQ0ZTBlMTEzMGU1ZjVhMjk5NTliMmJmZjE0NDQ. CSeq: 1 INVITE Content-Length: 0 5. AS <- MS (SIP 200 OK) ------------------------ SIP/2.0 200 OK Via: SIP/2.0/UDP 1.2.3.4:5060; \ branch=z9hG4bK-d8754z-8723e421ebc45f6b-1---d8754z-;rport=5060 Contact: To: ;tag=6a900179 From: ;tag=10514b7f Call-ID: NzI0ZjQ0ZTBlMTEzMGU1ZjVhMjk5NTliMmJmZjE0NDQ. CSeq: 1 INVITE Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, UPDATE, REGISTER Content-Type: application/sdp Content-Length: 374 v=0 o=lminiero 123456 654322 IN IP4 pippozzoserver.org s=MediaCtrl c=IN IP4 pippozzoserver.org t=0 0 m=audio 63442 RTP/AVP 0 3 8 101 a=rtpmap:0 PCMU/8000 a=rtpmap:3 GSM/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 a=ptime:20 a=label:7eda834 m=video 33468 RTP/AVP 98 a=rtpmap:98 H263-1998/90000 a=fmtp:98 CIF=2 a=label:0132ca2 6. UAC <- AS (SIP 200 OK) ------------------------- SIP/2.0 200 OK Amirante, et al. Expires September 5, 2009 [Page 18] Internet-Draft CFW Call Flow Examples March 2009 Via: SIP/2.0/UDP 4.3.2.1:5063;rport=5063; \ branch=z9hG4bK1396873708 Contact: To: ;tag=bcd47c32 From: ;tag=1153573888 Call-ID: 1355333098 CSeq: 20 INVITE Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, UPDATE, REGISTER Content-Type: application/sdp Content-Length: 374 v=0 o=lminiero 123456 654322 IN IP4 pippozzoserver.org s=MediaCtrl c=IN IP4 pippozzoserver.org t=0 0 m=audio 63442 RTP/AVP 0 3 8 101 a=rtpmap:0 PCMU/8000 a=rtpmap:3 GSM/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 a=ptime:20 a=label:7eda834 m=video 33468 RTP/AVP 98 a=rtpmap:98 H263-1998/90000 a=fmtp:98 CIF=2 a=label:0132ca2 7. UAC -> AS (SIP ACK) ---------------------- ACK sip:mediactrlDemo@cicciopernacchio.com SIP/2.0 Via: SIP/2.0/UDP 4.3.2.1:5063;rport;branch=z9hG4bK1113338059 From: ;tag=1153573888 To: ;tag=bcd47c32 Call-ID: 1355333098 CSeq: 20 ACK Contact: Max-Forwards: 70 User-Agent: Linphone/2.1.1 (eXosip2/3.0.3) Content-Length: 0 8. AS -> MS (SIP ACK) --------------------- ACK sip:MediaServer@pippozzoserver.org:5060;transport=UDP SIP/2.0 Via: SIP/2.0/UDP 1.2.3.4:5060; \ Amirante, et al. Expires September 5, 2009 [Page 19] Internet-Draft CFW Call Flow Examples March 2009 branch=z9hG4bK-d8754z-5246003419ccd662-1---d8754z-;rport Max-Forwards: 70 Contact: To: ;tag=10514b7f Call-ID: NzI0ZjQ0ZTBlMTEzMGU1ZjVhMjk5NTliMmJmZjE0NDQ. CSeq: 1 ACK Content-Length: 0 Figure 8: 3PCC SIP Signaling As a result of the 3PCC negotiation depicted in Figure 8, the following relevant information is retrieved: 1. The 'From' and 'To' tags (10514b7f and 6a900179 respectively) of the AS<->MS session: From: ;tag=10514b7f ^^^^^^^^ To: ;tag=6a900179 ^^^^^^^^ 2. the labels associated with the negotiated media connections, in this case an audio stream (7eda834) and a video stream (0132ca2). m=audio 63442 RTP/AVP 0 3 8 101 [..] a=label:7eda834 ^^^^^^^ m=video 33468 RTP/AVP 98 [..] a=label:0132ca2 ^^^^^^^ These three identifiers allow the AS and MS to univocally and unambiguously address to each other the connections associated with the related UAC, specifically: 1. 10514b7f~6a900179, the concatenation of the 'From' and 'To' tags, addresses all the media connections between the MS and the UAC; 2. 10514b7f~6a900179 <-> 7eda834, the association of the previous value with the label attribute, addresses only one of the media connections of the UAC session (in this case, the audio stream); Amirante, et al. Expires September 5, 2009 [Page 20] Internet-Draft CFW Call Flow Examples March 2009 since, as it will be clearer in the scenario examples, the explicit identifiers in requests can only address from~tag connections, additional mechanism will be required to have a finer control upon individual media streams (i.e. by means of the element in package level requests). The mapping the AS makes between the UACs<->AS and the AS<->MS SIP dialogs is instead out of scope for this document: we just assume that the AS knows how to address the right connection according to the related session it has with a UAC (e.g. to play an announcement to a specific UAC), which is obviously very important considering the AS is responsible for all the business logic of the multimedia application it provides. 6.1. Echo Test The echo test is the simpliest example scenario that can be achieved by means of a Media Server. It basically consists of a UAC directly or indirectly "talking" to itself. A media perspective of such a scenario is depicted in Figure 9. +-------+ A (RTP) +--------+ | UAC |=========================>| Media | | A |<=========================| Server | +-------+ A (RTP) +--------+ Figure 9: Echo Test: Media Perspective From the framework point of view, when the UAC's leg is not attached to anything yet, what appears is described in Figure 10: since there's no connection involving the UAC yet, the frames it might be sending are discarded, and nothing is sent to it (except for silence, if it is requested to be transmitted). MS +------+ UAC | | o----->>-------x | o.....<<.......x | | | +------+ Amirante, et al. Expires September 5, 2009 [Page 21] Internet-Draft CFW Call Flow Examples March 2009 Figure 10: Echo Test: UAC Media Leg not attached Starting from these considerations, two different approaches to the Echo Test scenario are explored in this document in the following paragraphs: 1. a Direct Echo Test approach, where the UAC directly talks to itself; 2. a Recording-based Echo Test approach, where the UAC indirectly talks to itself. 6.1.1. Direct Echo Test In the Direct Echo Test approach, the UAC is directly connected to itself. This means that, as depicted in Figure 11, each frame the MS receives from the UAC is sent back to it in real-time. MS +------+ UAC | | o----->>-------@ | o-----<<-------@ | | | +------+ Figure 11: Echo Test: Direct Echo (self connection) In the framework this can be achieved by means of the conference control package, which is in charge of joining connections and conferences. A sequence diagram of a potential transaction is depicted in Figure 12: Amirante, et al. Expires September 5, 2009 [Page 22] Internet-Draft CFW Call Flow Examples March 2009 UAC AS MS | | | | | 1. CONTROL (join UAC to itself) | | |++++++++++++++++++++++++++++++++>>| | | |--+ self | | | | join | | 2. 200 OK |<-+ UAC | |<<++++++++++++++++++++++++++++++++| | | | |<<######################################################>>| | Now the UAC is echoed back everything | |<<######################################################>>| | | | . . . . . . Figure 12: Self Connection: Framework Transaction All the transaction steps have been numbered to ease the understanding. A reference to the above numbered messages is in fact made in the following explanation lines: o The AS requests the joining of the connection to itself by sending a CONTROL request (1), specifically meant for the conferencing control package (msc-mixer/1.0), to the MS: since the connection must be attached to itself, both id1 and id2 attributes are set to the same value, i.e. the connectionid; o The MS, having checked the validity of the request, enforces the joining of the connection to itself; this means that all the frames sent by the UAC are sent back to it; to report the result of the operation, the MS sends a 200 OK (2) in reply to the AS, thus ending the transaction; the transaction ended successfully, as testified by the body of the message (the 200 status code in the tag). The complete transaction, that is the full bodies of the exchanged messages, is provided in the following lines: Amirante, et al. Expires September 5, 2009 [Page 23] Internet-Draft CFW Call Flow Examples March 2009 1. AS -> MS (CFW CONTROL) ------------------------- CFW 4fed9bf147e2 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 130 2. AS <- MS (CFW 200 OK) ------------------------ CFW 4fed9bf147e2 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 6.1.2. Echo Test based on Recording In the Recording-based Echo Test approach, instead, the UAC is NOT directly connected to itself, but rather indirectly. This means that, as depicted in Figure 13, each frame the MS receives from the UAC is first recorded: then, when the recording process is ended, the whole recorded frames are played back to the UAC as an announcement. MS +------+ UAC | | o----->>-------+~~~~~> (recording.wav) ~~+ o-----<<-------+ | | | ^ | v +--|---+ | +~~~~~~~~~~~<<~~~~~~~~~~~~+ Figure 13: Echo Test: Recording involved In the framework this can be achieved by means of the IVR control package, which is in charge of both the recording and the playout Amirante, et al. Expires September 5, 2009 [Page 24] Internet-Draft CFW Call Flow Examples March 2009 phases. However, the whole scenario cannot be accomplished in a single transaction; at least two steps, in fact, need to be performed: 1. first, a recording (preceded by an announcement, if requested) must take place; 2. then, a playout of the previously recorded media must occur. This means that two separate transactions need to be invoked. A sequence diagram of a potential multiple transaction is depicted in Figure 14: Amirante, et al. Expires September 5, 2009 [Page 25] Internet-Draft CFW Call Flow Examples March 2009 UAC AS MS | | | | | A1. CONTROL (record for 10s) | | |++++++++++++++++++++++++++++++++>>| | | A2. 202 | | |<<++++++++++++++++++++++++++++++++| prepare & | | |--+ start | | | | the | | A3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | A4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | "This is an echo test: tell something" | |<<########################################################| | | | |########################################################>>| | 10s of audio from the UAC are recorded |--+ save |########################################################>>| | in a | | |<-+ file | | B1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | Use recorded +--| B2. 200 OK | | file to play | |++++++++++++++++++++++++++++++++>>| | announcement +->| | | | C1. CONTROL (play recorded) | | |++++++++++++++++++++++++++++++++>>| | | C2. 202 | | |<<++++++++++++++++++++++++++++++++| prepare & | | |--+ start | | | | the | | C3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | C4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | "Can you hear me? It's me, UAC, talking" | |<<########################################################| | | | | | D1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | D2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | . . . . . . Amirante, et al. Expires September 5, 2009 [Page 26] Internet-Draft CFW Call Flow Examples March 2009 Figure 14: Recording-based Echo: Two Framework Transactions The first, obvious difference that comes out when looking at the diagram is that, unlike what happened in the Direct Echo example, the MS does not reply with a 200 message to the CONTROL request originated by the AS. Instead, a 202 provisional message is sent first, followed by a REPORT message. The 202+REPORT(s) mechanism is used whenever the MS wants to tell the AS that the requested operation might take some more time than expected. So, while the operation in the Direct Echo scenario was expected to be fulfilled in a very short time, the IVR request was assumed to last longer instead. A 202 message provides a timeout value and tells the AS to wait a bit, since the preparation of the dialog might not be an immediate task. In this example, the preparation ends before the timeout, and so the transaction is concluded with a 'REPORT terminate', which acts as the 200 message in the previous example. In case the preparation took longer than the timeout, an additional 'REPORT update' would have been sent with a new timeout value, and so on until completion by means of a 'REPORT terminate'. About the dialog itself, notice how the AS-originated CONTROL transactions are terminated as soon as the requested dialogs start: as specified in [I-D.ietf-mediactrl-ivr-control-package], the MS makes use of a framework CONTROL message to report the result of the dialog and how it has proceeded. The two transactions (the AS- generated CONTROL request and the MS-generated CONTROL event) are correlated by means of the associated dialog identifier, as it will be clearer from the following lines. As before, all the transaction steps have been numbered to ease the understanding and the following of the subsequent explanation lines. Besides, the two transactions are distinguished by the preceding letter (A,B=recording, C,D=playout). o The AS, as a first transaction, invokes a recording on the UAC connection by means of a CONTROL request (A1); the body is for the IVR package (msc-ivr/1.0), and requests the start (dialogstart) of a new recording context (); the recording must be preceded by an announcement (), must not last longer than 10s (maxtime), and cannot be interrupted by a DTMF tone (dtmfterm=false); this has only to be done once (repeatCount), which means that if the recording does not succeed the first time, the transaction must fail; a video recording is requested (type), which is to be fed by both the negotiated media streams; a beep has to be played (beep) right before the recording starts to notify the UAC; o As seen before, the MS sends a provisional 202 response, to let the AS know the operation might need some time; Amirante, et al. Expires September 5, 2009 [Page 27] Internet-Draft CFW Call Flow Examples March 2009 o In the meanwhile, the MS prepares the dialog (e.g. by retrieving the announcement file, for which a HTTP URL is provided, and by checking that the request is well formed) and if all is fine it starts it, notifying the AS about it with a new REPORT (A3) with a terminated status; as explained previously, interlocutory REPORT messages with an update status would have been sent in case the preparation took longer than the timeout provided in the 202 message (e.g. if retrieving the resource via HTTP took longer than expected); once the dialog has been prepared and started, the UAC connection is then passed to the IVR package, which first plays the announcement on the connection, followed by a beep, and then records all the incoming frames to a buffer; the MS also provides the AS with an unique dialog identifier (dialogid) which will be used in all subsequent event notifications concerning the dialog it refers to; o The AS acks the latest REPORT (A4), thus terminating this transaction, waiting for the result to come; o Once the recording is over, the MS prepares a notification CONTROL (B1); the body is prepared with an explicit reference to the previously provided dialogid identifier, in order to make the AS aware of the fact that the notification is related to that specific dialog; the event body is then completed with the recording related information () , in this case the path to the recorded file (here a HTTP URL) which can be used by the AS for whatever it needs to; the payload also contains information about the prompt (), which is however not relevant to the scenario; o The AS concludes this first recording transaction by acking the CONTROL event (B2). Now that the first transaction has ended, the AS has the 10s recording of the UAC talking. It can let the UAC hear it by having the MS play it to the MS as an announcement: o The AS, as a second transaction, invokes a playout on the UAC connection by means of a new CONTROL request (C1); the body is once againg for the IVR package (msc-ivr/1.0), but this time it requests the start (dialogstart) of a new announcement context (); the file to be played is the one recorded before (prompts), and has only to be played once (iterations); o Again, the usual provisional 202 (C2) takes place; o In the meanwhile, the MS prepares the new dialog and starts it, notifying the AS about it with a new REPORT (C3) with a terminated status: the connection is then passed to the IVR package, which plays the file on it; o The AS acks the terminating REPORT (C4), now waiting for the announcement to end; Amirante, et al. Expires September 5, 2009 [Page 28] Internet-Draft CFW Call Flow Examples March 2009 o Once the playout is over, the MS sends a CONTROL event (D1) which contains in its body () information about the just concluded announcement; as before, the proper dialogid is used as a reference to the correct dialog; o The AS concludes this second and last transaction by acking the CONTROL event (D2). As in the previous paragraph, the whole CFW interaction is provided for a more in depth evaluation of the protocol interaction. A1. AS -> MS (CFW CONTROL, record) ---------------------------------- CFW 796d83aa1ce4 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 265 A2. AS <- MS (CFW 202) ---------------------- CFW 796d83aa1ce4 202 A3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 796d83aa1ce4 REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 A4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 796d83aa1ce4 200 Seq: 1 B1. AS <- MS (CFW CONTROL event) -------------------------------- CFW 0eb1678c0bfc CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 403 B2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 0eb1678c0bfc 200 C1. AS -> MS (CFW CONTROL, play) -------------------------------- CFW 1632eead7e3b CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 241 C2. AS <- MS (CFW 202) ---------------------- CFW 1632eead7e3b 202 C3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 1632eead7e3b REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 C4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 1632eead7e3b 200 Seq: 1 D1. AS <- MS (CFW CONTROL event) -------------------------------- CFW 502a5fd83db8 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 230 Amirante, et al. Expires September 5, 2009 [Page 31] Internet-Draft CFW Call Flow Examples March 2009 D2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 502a5fd83db8 200 6.2. Phone Call Another scenario that might involve the interaction between an AS and a MS is the classic phone call between two UACs. In fact, even though the most straightforward way to achieve this would be to let the UACs negotiate the session and the media to make use of between themselves, there are cases when the services provided by a MS might prove useful for phone calls as well. One of these cases is when the two UACs have no common supported codecs: having the two UACs directly negotiate the session would result in a session with no available media. Involving the MS as a transcoder would instead allow the two UACs to communicate anyway. Another interesting case is when the AS (or any other entity the AS is working in behalf of) is interested in manipulating or monitoring the media session between the UACs, e.g. to record the conversation: a similar scenario will be dealt with in Section 6.2.2. Before proceeding in looking at how such a scenario might be accomplished by means of the Media Control Channel Framework, it is worth spending a couple of words upon how the SIP signaling involving all the interested parties might look like. In fact in such a scenario a 3PCC approach is absolutely needed. An example is provided in Figure 15. Again, the presented example is not at all to be considered best common practice when 3PCC is needed in a MediaCtrl-based framework. It is only described in order to let the reader more easily understand what are the requirements on the MS side, and as a consequence which information might be required. [RFC3725] provides a much more detailed overview on 3PCC patterns in several use cases. Only an explanatory sequence diagram is provided, without delving into the details of the exchanged SIP messages. Amirante, et al. Expires September 5, 2009 [Page 32] Internet-Draft CFW Call Flow Examples March 2009 UAC(1) UAC(2) AS MS | | | | | INVITE (offer A) | | |---------------------------------->| | | | 100 Trying | | |<----------------------------------| | | | INVITE (no offer) | | | |<--------------------| | | | 180 Ringing | | | |-------------------->| | | | 180 Ringing | | |<----------------------------------| INVITE (offer A) | | | |-------------------------->| | | | 200 OK (offer A') | | | |<--------------------------| | | | ACK | | | |-------------------------->| | | 200 OK (offer B) | | | |-------------------->| INVITE (offer B) | | | |-------------------------->| | | | 200 OK (offer B') | | | |<--------------------------| | | | ACK | | | ACK (offer B') |-------------------------->| | |<--------------------| | | | 200 OK (offer A') | | |<----------------------------------| | | ACK | | | |---------------------------------->| | | | | | . . . . . . . . Figure 15: Phone Call: Example of 3PCC In the example, the UAC1 wants to place a phone call to UAC2. To do so, it sends an INVITE to the AS with its offer A. The AS sends an offerless INVITE to UAC2. When the UAC2 responds with a 180, the same message is forwarded by the AS to the UAC1 to notify it the callee is ringing. In the meanwhile, the AS also adds a leg to the MS for UAC1, as explained in the previous sections: to do so it of course makes use of the offer A the UAC1 made. Once the UAC2 accepts the call, by providing its own offer B in the 200, the AS adds a leg for it too to the MS. At this point, the negotiation can be completed by providing the two UACs with the SDP answer negotiated by the MS with them (A' and B' respectively). Amirante, et al. Expires September 5, 2009 [Page 33] Internet-Draft CFW Call Flow Examples March 2009 This is only one way to deal with the signaling, and shall not absolutely be considered as a mandatory approach of course. Once the negotiation is over, the two UACs are not in communication yet. In fact, it's up to the AS now to actively trigger the MS into attaching their media streams to each other someway, by referring to the connection identifiers associated with the UACs as explained previously. This document presents two different approaches that might be followed, according to what needs to be accomplished. A generic media perspective of the phone call scenario is depicted in Figure 16: the MS is basically in the media path between the two UACs. +-------+ UAC1 (RTP) +--------+ UAC1 (RTP) +-------+ | UAC |===================>| Media |===================>| UAC | | 1 |<===================| Server |<===================| 2 | +-------+ UAC2 (RTP) +--------+ UAC2 (RTP) +-------+ Figure 16: Phone Call: Media Perspective From the framework point of view, when the UACs' legs are not attached to anything yet, what appears is described in Figure 17: since there are no connections involving the UACs yet, the frames they might be sending are discarded, and nothing is sent to them (except for silence, if it is requested to be transmitted). MS +--------------+ UAC 1 | | UAC 2 o----->>-------x x.......>>.....o o.....<<.......x x-------<<-----o | | +--------------+ Figure 17: Phone Call: UAC Media Leg not attached 6.2.1. Direct Connection The Direct Connection is the easiest and more straightforward approach to get the phone call between the two UACs to work. The idea is basically the same as the one in the Direct Echo approach: a directive is used to directly attach one UAC to the other, by Amirante, et al. Expires September 5, 2009 [Page 34] Internet-Draft CFW Call Flow Examples March 2009 exploiting the MS to only deal with the transcoding/adaption of the flowing frames, if needed. This approach is depicted in Figure 18. MS +--------------+ UAC 1 | | UAC 2 o----->>-------+~~~>>~~~+------->>-----o o-----<<-------+~~~<<~~~+-------<<-----o | | +--------------+ Figure 18: Phone Call: Direct Connection UAC1 UAC2 AS MS | | | | | | | 1. CONTROL (join UAC1 to UAC2) | | | |++++++++++++++++++++++++++++++++++>>| | | | |--+ join | | | | | UAC1 | | | 2. 200 OK |<-+ UAC2 | | |<<++++++++++++++++++++++++++++++++++| | | | | |<<#######################################################>>| | UAC1 can hear UAC2 talking | |<<#######################################################>>| | | | | | |<<###########################################>>| | | UAC2 can hear UAC1 talking | | |<<###########################################>>| | | | | |<*talking*>| | | . . . . . . . . Figure 19: Direct Connection: Framework Transactions The framework transactions needed to accomplish this scenario are very trivial and easy to understand. They basically are the same as the ones presented in the Direct Echo Test scenario, with the only difference being in the provided identifiers. In fact, this time the Amirante, et al. Expires September 5, 2009 [Page 35] Internet-Draft CFW Call Flow Examples March 2009 MS is not supposed to attach the UACs' media connections to themselves, but has to join the media connections of two different UACs, i.e. UAC1 and UAC2. This means that, in this transaction, id1 and i2 will have to address the media connections of UAC1 and UAC2. In case of a successful transaction, the MS takes care of forwarding all media coming from UAC1 to UAC2 and vice versa, transparently taking care of any required transcoding steps, if necessary. 1. AS -> MS (CFW CONTROL) ------------------------- CFW 0600855d24c8 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 130 2. AS <- MS (CFW 200 OK) ------------------------ CFW 0600855d24c8 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 Such a simple approach has its drawbacks. For instance, with such an approach recording a conversation between two users might be tricky to accomplish. In fact, since no mixing would be involved, only the single connections (UAC1<->MS and UAC2<->MS) could be recorded. If the AS wants a conversation recording service to be provided anyway, it needs additional business logic on its side. An example of such a use case is provided in Section 6.2.3. 6.2.2. Conference-based Approach The approach described in Section 6.2.1 surely works for a basic phone call, but as already explained might have some drawbacks whenever more advanced features are needed. For intance, you can't record the whole conversation, only the single connections, since no Amirante, et al. Expires September 5, 2009 [Page 36] Internet-Draft CFW Call Flow Examples March 2009 mixing is involved. Besides, even the single task of playing an announcement over the conversation could be complex, especially if the MS does not support implicit mixing over media connections. For this reason, in more advanced cases a different approach might be taken, like the conference-based approach described in this section. The idea is to make use of a mixing entity in the MS that acts as a bridge between the two UACs: the presence of this entity allows for more customization on what needs to be done on the conversation, like the recording of the conversation that has been provided as an example. The approach is depicted in Figure 20. The mixing functionality in the MS will be described in more detail in the following section (which deals with many conference-related scenarios), so only some hints will be provided here for a basic comprehension of the approach. MS +---------------+ UAC A | | UAC B o----->>-------+~~>{#}::>+:::::::>>:::::o o:::::<<:::::::+<::{#}<~~+-------<<-----o | : | | : | +-------:-------+ : +::::> (conversation.wav) Figure 20: Phone Call: Conference-based Approach To identify a single sample scenario, let's consider a phone call the AS wants to be recorded. Figure 21 shows how this could be accomplished in the Media Control Channel Framework: the example, as usual, hides the previous interaction between the UACs and the AS, and instead focuses on the control channel operations and what follows. Amirante, et al. Expires September 5, 2009 [Page 37] Internet-Draft CFW Call Flow Examples March 2009 UAC1 UAC2 AS MS | | | | | | | A1. CONTROL (create conference) | | | |++++++++++++++++++++++++++++++++>>| | | | |--+ create | | | | | conf and | | | A2. 200 OK (conferenceid=Y) |<-+ its ID | | |<<++++++++++++++++++++++++++++++++| | | | | | | | B1. CONTROL (record for 1800s) | | | |++++++++++++++++++++++++++++++++>>| | | | B2. 202 |--+ start | | |<<++++++++++++++++++++++++++++++++| | the | | | B3. REPORT (terminate) |<-+ dialog | | |<<++++++++++++++++++++++++++++++++| | Recording +--| B4. 200 OK | | of the mix | |++++++++++++++++++++++++++++++++>>| | has started +->| | | | | C1. CONTROL (join UAC1<->confY) | | | |++++++++++++++++++++++++++++++++>>| | | | |--+ join | | | | | UAC1 & | | | C2. 200 OK |<-+ conf Y | | |<<++++++++++++++++++++++++++++++++| | | | | |<<####################################################>>| | Now the UAC1 is mixed in the conference | |<<####################################################>>| | | | | | | | D1. CONTROL (join UAC2<->confY) | | | |++++++++++++++++++++++++++++++++>>| | | | |--+ join | | | | | UAC2 & | | | D2. 200 OK |<-+ conf Y | | |<<++++++++++++++++++++++++++++++++| | | | | | |<<########################################>>| | | Now the UAC2 is mixed too | | |<#########################################>>| | | | | |<*talking*>| | | | | | | . . . . . . . . Figure 21: Conference-based Approach: Framework Transactions Amirante, et al. Expires September 5, 2009 [Page 38] Internet-Draft CFW Call Flow Examples March 2009 The AS makes use of two different packages to accomplish this scenario: the mixer package (to create the mixing entity and join the UACs) and the IVR package (to record what happens in the conference). The framework transaction steps can be described as follows: o First of all, the AS creates a new hidden conference by means of a 'createconference' request (A1); this conference is properly configured according to the use it is assigned to; in fact, since only two participants will be joined to it, both 'reserved- talkers' and 'reserved-listeners' are set to 2, just as the 'n' value for the N-best audio mixing algorithm; besides, the video layout as well is set accordingly (single-view/dual-view); o the MS notifies the successful creation of the new conference in a 200 framework message (A2); the identifier assigned to the conference, which will be used in subsequent requests addressed to it, is 6013f1e; o the AS requests a new recording upon the newly created conference; to do so, it places a proper request to the IVR package (B1); the AS is interested in a video recording (type=video/mpeg), which must not last longer than 3 hours (maxtime=1800s), after which the recording must end; besides, no beep must be played on the conference (beep=false), and the recording must start immediately whether or not any audio activity has been reported (vadinitial=false); o the transaction is extended by the MS (B3), and when the dialog has been successfully started, a REPORT terminate is issued to the AS (B4); the message contains the dialogid associated with the dialog (00b29fb), which the AS must refer to for later notifications; o at this point, the AS attaches both UACs to the conference with two separate 'join' directives (C1/D1); when the MS confirms the success of both operations (C2/D2), the two UACs are actually in contact with each other (even though indirectly, since a hidden conference they're unaware of is on their path) and their media contribution is recorded. A1. AS -> MS (CFW CONTROL, createconference) -------------------------------------------- CFW 238e1f2946e8 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 395 Amirante, et al. Expires September 5, 2009 [Page 39] Internet-Draft CFW Call Flow Examples March 2009 single-view dual-view A2. AS <- MS (CFW 200 OK) ------------------------- CFW 238e1f2946e8 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 151 B1. AS -> MS (CFW CONTROL, record) ---------------------------------- CFW 515f007c5bd0 CONTROL Control-Package: msc-ivr Content-Type: application/msc-ivr+xml Content-Length: 207 B2. AS <- MS (CFW 202) ---------------------- CFW 515f007c5bd0 202 B3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 515f007c5bd0 REPORT Seq: 1 Status: terminate Amirante, et al. Expires September 5, 2009 [Page 40] Internet-Draft CFW Call Flow Examples March 2009 Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 B4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 515f007c5bd0 200 Seq: 1 C1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 0216231b1f16 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 123 C2. AS <- MS (CFW 200 OK) ------------------------- CFW 0216231b1f16 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 D1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 140e0f763352 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 124 Amirante, et al. Expires September 5, 2009 [Page 41] Internet-Draft CFW Call Flow Examples March 2009 D2. AS <- MS (CFW 200 OK) ------------------------- CFW 140e0f763352 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 The recording of the conversation can subsequently be accessed by the AS by waiting for an event notification from the MS: this event, which will be associated with the previously started recording dialog, will contain the URI to the recorded file. Such an event may be triggered either by a natural completion of the dialog (e.g. the dialog has reached its programmed 3 hours) or by any interruption of the dialog itself (e.g. the AS actively requests the recording to be interrupted since the call between the UACs ended). 6.2.3. Recording a conversation The previous section described how to take advantage of the conferencing functionality of the mixer package in order to allow the recording of phone calls in a simple way. However, making use of a dedicated mixer just for a phone call might be considered overkill. This section shows how recording a conversation and playing it out subsequently can be accomplished without a mixing entity involved in the call, that is by using the direct connection approach as described in Section 6.2.1. As already explained previously, in case the AS wants to record a phone call between two UACs, the use of just the directive without a mixer forces the AS to just rely on separate recording commands. That is, the AS can only instruct the MS to separately record the media flowing on each media leg: a recording for all the data coming from UAC1, and a different recording for all the data coming from UAC2. In case someone wants to access the whole conversation subsequently, the AS may take at least two different approaches: 1. it may mix the two recordings itself (e.g. by delegating it to an offline mixing entity) in order to obtain a single file containing the combination of the two recordings; this way, a Amirante, et al. Expires September 5, 2009 [Page 42] Internet-Draft CFW Call Flow Examples March 2009 simple playout as described in Section 6.1.2 would suffice; 2. alternatively, it may take advantage of the mixing functionality provided by the MS itself; a way to do so is to create a hidden conference on the MS, attach the UAC as a passive participant to it, and play the separate recordings on the conference as announcements; this way, the UAC accessing the recording would experience both the recordings at the same time. It is of course option 2 that is considered in this section. The framework transaction as described in Figure 22 assumes that a recording has already been requested for both UAC1 and UAC2, that the phone call has ended and that the AS has successfully received the URIs to both the recordings from the MS. Such steps are not described again since they would be quite similar to the ones described in Section 6.1.2. As anticipated, the idea is to make use of a properly constructed hidden conference to mix the two separate recordings on the fly and present them to the UAC. It is of course up to the AS to subsequently unjoin the user from the conference and destroy the conference itself once the playout of the recordings ends for any reason. UAC AS MS | | | | (UAC1 and UAC2 have previously been recorded: the AS has | | the two different recordings available for playout). | | | | | | A1. CONTROL (create conference) | | |++++++++++++++++++++++++++++++++>>| | | |--+ create | | | | conf & | | A2. 200 OK (conferenceid=Y) |<-+ its ID | |<<++++++++++++++++++++++++++++++++| | | | | | B1. CONTROL (join UAC & confY) | | |++++++++++++++++++++++++++++++++>>| | | |--+ join | | | | UAC & | | B2. 200 OK |<-+ conf Y | |<+++++++++++++++++++++++++++++++++| | | | |<<######################################################>>| | UAC is now a passive participant in the conference | |<<######################################################>>| | | | | | C1. CONTROL (play UAC1 on confY) | | |++++++++++++++++++++++++++++++++>>| Amirante, et al. Expires September 5, 2009 [Page 43] Internet-Draft CFW Call Flow Examples March 2009 | | D1. CONTROL (play UAC2 on confY) | | |++++++++++++++++++++++++++++++++>>| | | C2. 202 | | |<<++++++++++++++++++++++++++++++++| | | D2. 202 |--+ Start | |<<++++++++++++++++++++++++++++++++| | both | | C3. REPORT (terminate) | | the | |<<++++++++++++++++++++++++++++++++| |dialogs | | D3. REPORT (terminate) |<-+ | |<<++++++++++++++++++++++++++++++++| | | C4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | D4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | The two recordings are mixed and played together to UAC | |<<########################################################| | | | | | E1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | E2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | F1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | F2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | . . . . . . Figure 22: Phone Call: Playout of a Recorded Conversation The diagram above assumes a recording of both the channels has already taken place. It may have been requested by the AS either shortly before joining UAC1 and UAC2, or shortly after that transaction. Whenever that happened, a recording is assumed to have taken place, and so the AS is supposed to have both the recordings available for playback. Once a new user, UAC, wants to access the recorded conversation, the AS takes care of the presented transactions. The framework transaction steps are only apparently more complicated than the ones presented so far. The only difference, in fact, is that transactions C and D are concurrent, since the recordings must be played together. Amirante, et al. Expires September 5, 2009 [Page 44] Internet-Draft CFW Call Flow Examples March 2009 o First of all, the AS creates a new conference to act as a mixing entity (A1); the settings for the conference are chosen according to the use case, e.g. the video layout which is fixed to 'dual- view' and the switching type to 'controller'; when the conference has been successfully created (A2) the AS takes note of the conference identifier; o At this point, the UAC is attached to the conference as a passive user (B1); there would be no point in letting the user contribute to the conference mix, since he will only need to watch a recording; in order to specify his passive status, both the audio and video streams for the user are set to 'recvonly'; in case the transaction succeeds, the MS notifies it to the AS (B2); o Once the conference has been created and UAC has been attached to it, the AS can request the playout of the recordings; in order to do so, it requests two concurrent directives (C1 and D1), addressing respectively the recording of UAC1 and UAC2; both the prompts must be played on the previously created conference and not to UAC directly, as can be deduced from the 'conferenceid' attribute of the element; o The transactions live their life exactly as explained for previous examples; the originating transactions are first prepared and started (C2-4, D2-4), and then, as soon as any of the playout ends, a realted CONTROL message to notify this is triggered by the MS (E1, F1); the notification may contain a element with information about how the playout proceeded (e.g. whether the playout completed normally, or interrupted by a DTMF tone, etc.). A1. AS -> MS (CFW CONTROL, createconference) -------------------------------------------- CFW 506e039f65bd CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 312 dual-view A2. AS <- MS (CFW 200 OK) Amirante, et al. Expires September 5, 2009 [Page 45] Internet-Draft CFW Call Flow Examples March 2009 ------------------------- CFW 506e039f65bd 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 151 B1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 09202baf0c81 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 214 B2. AS <- MS (CFW 200 OK) ------------------------- CFW 09202baf0c81 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 C1. AS -> MS (CFW CONTROL, play recording from UAC1) ---------------------------------------------------- CFW 3c2a08be4562 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 229 Amirante, et al. Expires September 5, 2009 [Page 46] Internet-Draft CFW Call Flow Examples March 2009 D1. AS -> MS (CFW CONTROL, play recording from UAC2) ---------------------------------------------------- CFW 1c268d810baa CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 229 C2. AS <- MS (CFW 202) ---------------------- CFW 3c2a08be4562 202 D2. AS <- MS (CFW 202) ---------------------- CFW 1c268d810baa 202 C3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 1c268d810baa REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 Amirante, et al. Expires September 5, 2009 [Page 47] Internet-Draft CFW Call Flow Examples March 2009 D3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 3c2a08be4562 REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 C4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 1c268d810baa 200 Seq: 1 D4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 3c2a08be4562 200 Seq: 1 E1. AS <- MS (CFW CONTROL event, playout of recorded UAC1 ended) ---------------------------------------------------------------- CFW 77aec0735922 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 230 Amirante, et al. Expires September 5, 2009 [Page 48] Internet-Draft CFW Call Flow Examples March 2009 E2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 77aec0735922 200 F1. AS <- MS (CFW CONTROL event, playout of recorded UAC2 ended) ---------------------------------------------------------------- CFW 62726ace1660 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 230 F2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 62726ace1660 200 6.3. Conferencing One of the most important services the MS must be able to provide is mixing. This involves mixing media streams from different sources, and delivering the resulting mix(es) to each interested party, often according to per-user policies, settings and encoding. A typical scenario involving mixing is of course media conferencing. In such a scenario, the media sent by each participant is mixed, and each participant typically receives the overall mix excluding its own contribtion and encoded in the format it negotiated. This example points out in a quite clear way how mixing must take care of the profile of each involved entity. A media perspective of such a scenario is depicted in Figure 23. Amirante, et al. Expires September 5, 2009 [Page 49] Internet-Draft CFW Call Flow Examples March 2009 +-------+ | UAC | | C | +-------+ " ^ C (RTP) " " " " " " A+B (RTP) v " +-------+ A (RTP) +--------+ A+C (RTP) +-------+ | UAC |===================>| Media |===================>| UAC | | A |<===================| Server |<===================| B | +-------+ B+C (RTP) +--------+ B (RTP) +-------+ Figure 23: Conference: Media Perspective From the framework point of view, when the UACs' legs are not attached to anything yet, what appears is described in Figure 24: since there are no connections involving the UACs yet, the frames they might be sending are discarded, and nothing is sent back to them either (except for silence, if it is requested to be transmitted). MS +----------------+ UAC A | | UAC B o----->>-------x x.......>>.....o o.....<<.......x x-------<<-----o | | | | | xx | | |. | +-------|.-------+ |. ^v ^v |. oo UAC C Figure 24: Conference: UAC Legs not attached The next subsections will cover several typical scenarios involving mixing and conferencing as a whole, specifically: Amirante, et al. Expires September 5, 2009 [Page 50] Internet-Draft CFW Call Flow Examples March 2009 1. Simple Bridging, where the scenario will be a very basic (i.e. no "special effects", just mixing involved) conference involving one or more participants; 2. Rich Conference Scenario, which enriches the Simple Bridging scenario by adding additional features typically found in conferencing systems (e.g. DTMF collection for PIN-based conference access, private and global announcements, recordings and so on); 3. Coaching Scenario, a more complex scenario which involves per- user mixing (customers, agents and coaches don't get all the same mixes); 4. Sidebars Scenario, which adds more complexity to the previous conferencing scenarios by involving sidebars (i.e. separate conference instances that only exist within the context of a parent conference instance) and the custom media delivery that follows. All of the above mentioned scenarios depend on the availability of a mixing entity. Such an entity is provided in the Media Control Channel Framework by the conferencing package. This package in fact, besides allowing for the interconnection of media sources as seen in the Direct Echo Test section, enables the creation of abstract connections that can be joined to multiple connections: these abstract connections, called conferences, mix the contribution of each attached connection and feed them accordingly (e.g. a connection with 'sendrecv' property would be able to contribute to the mix and to listen to it, while a connection with a 'recvonly' property would only be able to listen to the overall mix but not to actively contribute to it). That said, each of the above mentioned scenarios will start more or less in the same way: by the creation of a conference connection (or more than one, as needed in some cases) to be subsequently referred to when it comes to mixing. A typical framework transaction to create a new conference instance in the Media Control Channel Framework is depicted in Figure 25: Amirante, et al. Expires September 5, 2009 [Page 51] Internet-Draft CFW Call Flow Examples March 2009 AS MS | | | 1. CONTROL (create conference) | |++++++++++++++++++++++++++++++++>>| | |--+ create | | | conf and | 2. 200 OK (conferenceid=Y) |<-+ its ID |<<++++++++++++++++++++++++++++++++| map URI +--| | X with | | | conf Y +->| | | | . . . . Figure 25: Conference: Framework Transactions The call flow is quite straightforward, and can typically be summarized in the following steps: o The AS invokes the creation of a new conference instance by means of a CONTROL request (1); this request is addressed to the conferencing package (msc-mixer/1.0) and contains in the body the directive (createconference) with all the desired settings for it; in the example, the mixing policy is to mix the five (reserved- talkers) loudest speakers (nbest), while ten listeners at max are allowed; video settings are configured, including the mechanism used to select active video sources (controller, meaning the AS will explicitly instruct the MS about it) and details about the video layouts to make available; in this example, the AS is instructing the MS to use a single-view layout when only one video source is active, to pass to a quad-view layout when at least two video sources are active, and to use a 5x1 layout whenever the number of sources is at least five; finally, the AS also subscribes to the "active-talkers" event, which means it wants to be informed (at a rate of 4 seconds) whenever an active participant is speaking; o The MS creates the conference instance assigning a unique identifier to it (6146dd5), and completes the transaction with a 200 response (2); o At this point, the requested conference instance is active and ready to be used by the AS; it is then up to the AS to integrate the use of this identifier in its application logic. Amirante, et al. Expires September 5, 2009 [Page 52] Internet-Draft CFW Call Flow Examples March 2009 1. AS -> MS (CFW CONTROL) ------------------------- CFW 3032e5fb79a1 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 489 single-view quad-view multiple-5x1 2. AS <- MS (CFW 200) --------------------- CFW 3032e5fb79a1 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 151 6.3.1. Simple Bridging As already introduced before, the simplest use an AS can make of a conference instance is simple bridging. In this scenario, the conference instance just acts as a bridge for all the participants that are attached to it. The bridge takes care of transcoding, if needed (in general, different participants may make use of different codecs for their streams), echo cancellation (each participant will receive the overall mix excluding its own contribution) and per- participant mixing (each participant may receive different mixed streams, according to what it needs/is allowed to send/receive). This assumes of course that each interested participant must be Amirante, et al. Expires September 5, 2009 [Page 53] Internet-Draft CFW Call Flow Examples March 2009 joined somehow to the bridge in order to indirectly communicate with the other paricipants. From the media perspective, the scenario can be seen as depicted in Figure 26. MS +-----------------+ UAC A | | UAC B o----->>-------+~~~>{##}:::>+:::::::>>:::::o o:::::<<:::::::+<:::{##}<~~~+-------<<-----o | ^: | | |v | | ++ | | |: | +--------|:-------+ |: ^v ^v |: oo UAC C Figure 26: Conference: Simple Bridging In the framework, the first step is obviously to create a new conference instance as seen in the introductory section (Figure 25). Assuming a conference instance has already been created, bridging participants to it is quite straightforward, and can be accomplished as already seen in the Direct Echo Test Scenario: the only difference here is that each participant is not directly connected to itself (Direct Echo) or another UAC (Direct Connection) but to the bridge instead. Figure 27 shows the example of two different UACs joining the same conference: the example, as usual, hides the previous interaction between each of the two UACs and the AS, and instead focuses on what the AS does in order to actually join the participants to the bridge so that they can interact in a conference. Amirante, et al. Expires September 5, 2009 [Page 54] Internet-Draft CFW Call Flow Examples March 2009 UAC1 UAC2 AS MS | | | | | | | A1. CONTROL (join UAC1 and confY) | | | |++++++++++++++++++++++++++++++++++>>| | | | |--+ join | | | | | UAC1 & | | | A2. 200 OK |<-+ conf Y | | |<<++++++++++++++++++++++++++++++++++| | | | | |<<######################################################>>| | Now UAC1 is mixed in the conference | |<<######################################################>>| | | | | | | | B1. CONTROL (join UAC2 and confY) | | | |++++++++++++++++++++++++++++++++++>>| | | | |--+ join | | | | | UAC2 & | | | B2. 200 OK |<-+ conf Y | | |<<++++++++++++++++++++++++++++++++++| | | | | | |<<###########################################>>| | | Now UAC2 too is mixed in the conference | | |<<###########################################>>| | | | | . . . . . . . . Figure 27: Simple Bridging: Framework Transactions (1) The framework transaction steps are actually quite trivial to understand, since they're very similar to some previously described scenarios. What the AS does is just joining both UAC1 (id1 in A1) and UAC2 (id1 in B1) to the conference (id2 in both transactions). As a result of these two operations, both UACs are mixed in the conference. Since no is explicitly provided in any of the transactions, all the media from the UACs (audio/video) are attached to the conference (as long as the conference has been properly configured to support both, of course). Amirante, et al. Expires September 5, 2009 [Page 55] Internet-Draft CFW Call Flow Examples March 2009 A1. AS -> MS (CFW CONTROL) -------------------------- CFW 434a95786df8 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 120 A2. AS <- MS (CFW 200 OK) ------------------------- CFW 434a95786df8 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 B1. AS -> MS (CFW CONTROL) -------------------------- CFW 5c0cbd372046 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 120 B2. AS <- MS (CFW 200 OK) ------------------------- CFW 5c0cbd372046 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 Amirante, et al. Expires September 5, 2009 [Page 56] Internet-Draft CFW Call Flow Examples March 2009 Once one or more participants have been attached to the bridge, their connections and how their media are handled by the bridge can be dynamically manipulated by means of another directive, called : a typical use case for this directive is the change of direction of an existing media (e.g. a previously speaking participant is muted, which means its media direction changes from 'sendrecv' to 'recvonly'). Figure 28 shows how a framework transaction requesting such a directive might appear. UAC1 UAC2 AS MS | | | | | | | 1. CONTROL (modifyjoin UAC1) | | | |++++++++++++++++++++++++++++++++>>| | | | |--+ modify | | | | | join | | | 2. 200 OK |<-+ settings | | |<<++++++++++++++++++++++++++++++++| | | | | |<<######################################################| | Now UAC1 can receive but not send (recvonly) | |<<######################################################| | | | | . . . . . . . . Figure 28: Simple Bridging: Framework Transactions (2) The directive used to modify an existing join configuration is , and its syntax is exactly the same as the one required in instructions. In fact, the same syntax is used for identifiers (id1/id2). Whenever a modifyjoin is requested and id1 and id2 address one or more joined connections, the AS is requesting a change of the join configuration. In this case, the AS instructs the MS to mute (stream=audio, direction=recvonly) UAC1 (id1=UAC1) in the conference (id2) it has been attached to previously. Any other connection existing between them is left untouched. It is worth noticing that the settings are enforced according to both the provided direction AND the id1 and id2 identifiers. For instance, in this example id1 refers to UAC1, while id2 to the conference in the MS. This means that the required modifications have to be applied to the stream specified in the element of the message, along the direction which goes from 'id1' to 'id2' (as specified in the element of the message). In the provided example, the AS wants to mute UAC1 with Amirante, et al. Expires September 5, 2009 [Page 57] Internet-Draft CFW Call Flow Examples March 2009 respect to the conference. To do so, the direction is set to 'recvonly', meaning that, for what concerns id1, the media stream is only to be received. If id1 referred to the conference and id2 to the UAC1, to achieve the same result the direction would have to be set to 'sendonly', meaning 'id1 (the conference) can only send to id2 (UAC1), and no media stream must be received'. Additional settings upon a (e.g. audio volume, region assignments and so on) follow the same approach, as it is presented in subsequent sections. 1. AS -> MS (CFW CONTROL) ------------------------- CFW 57f2195875c9 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 182 2. AS <- MS (CFW 200 OK) ------------------------ CFW 57f2195875c9 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 123 6.3.2. Rich Conference Scenario The previous scenario can be enriched with additional features often found in existing conferencing systems. Typical examples include IVR-based menus (e.g. the DTMF collection for PIN-based conference access), partial and complete recordings in the conference (e.g. for the "state your name" functionality and recording of the whole conference), private and global announcements and so on. All of this can be achieved by means of the functionality provided by the MS. In fact, even if the conferencing and IVR features come from different packages, the AS can interact with both of them and achieve complex Amirante, et al. Expires September 5, 2009 [Page 58] Internet-Draft CFW Call Flow Examples March 2009 results by correlating the effects of different transactions in its application logic. From the media and framework perspective, a typical rich conferencing scenario can be seen as it is depicted in Figure 29. MS +-------- (announcement.wav) (conference_recording.wav) <:::::+| :| +--------:|--------+ UAC A | :v | UAC B o----->>-------+~~~>{##}:::>+:::::::>>:::::o o:::::<<:::::::+<:::{##}<~~~+-------<<-----o | ^: | | | |v v | | ++ * (collect DTMF, get name) | |: | +--------|:--------+ |: ^v ^v |: oo UAC C Figure 29: Conference: Rich Conference Scenario To identify a single sample scenario, let's consider this sequence for a participant joining a conference (which again we assume has already been created): 1. The UAC as usual INVITEs a URI associated with a conference, and the AS follows the already explained procedure to have the UAC negotiate a new media session with the MS; 2. The UAC is presented with an IVR menu, in which it is requested to digit a PIN code to access the conference; 3. If the PIN is correct, the UAC is asked to state its name so that it can be recorded; 4. The UAC is attached to the conference, and the previously recorded name is announced globally to the conference to advertise its arrival. Figure 30 shows a single UAC joining a conference: the example, as usual, hides the previous interaction between the UAC and the AS, and Amirante, et al. Expires September 5, 2009 [Page 59] Internet-Draft CFW Call Flow Examples March 2009 instead focuses on what the AS does to actually interact with the participant and join it to the conference bridge. UAC AS MS | | | | | A1. CONTROL (request DTMF PIN) | | |++++++++++++++++++++++++++++++++>>| | | A2. 202 | | |<<++++++++++++++++++++++++++++++++| | | |--+ start | | | | the | | A3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | A4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | "Please digit the PIN number to join the conference" | |<<########################################################| | | | |########################################################>>| | DTMF digits are collected |--+ get |########################################################>>| | DTMF | | |<-+ digits | | B1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | Compare DTMF +--| B2. 200 OK | | digits with | |++++++++++++++++++++++++++++++++>>| | the PIN number +->| | | | C1. CONTROL (record name) | | |++++++++++++++++++++++++++++++++>>| | | C2. 202 | | |<<++++++++++++++++++++++++++++++++| | | |--+ start | | | | the | | C3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | C4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | "Please state your name after the beep" | |<<########################################################| | | | |########################################################>>| | Audio from the UAC is recorded (until timeout or DTMF) |--+ save Amirante, et al. Expires September 5, 2009 [Page 60] Internet-Draft CFW Call Flow Examples March 2009 |########################################################>>| | in a | | |<-+ file | | D1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | Store recorded +--| D2. 200 OK | | file to play | |++++++++++++++++++++++++++++++++>>| | announcement in +->| | | conference later | | | | E1. CONTROL (join UAC & confY) | | |++++++++++++++++++++++++++++++++>>| | | |--+ join | | | | UAC & | | E2. 200 OK |<-+ conf Y | |<+++++++++++++++++++++++++++++++++| | | | |<<######################################################>>| | UAC is now included in the mix of the conference | |<<######################################################>>| | | | | | F1. CONTROL (play name on confY) | | |++++++++++++++++++++++++++++++++>>| | | F2. 202 | | |<<++++++++++++++++++++++++++++++++| | | |--+ start | | | | the | | F3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | F4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | Global announcement: "Simon has joined the conference" | |<<########################################################| | | | | | G1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | G2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | . . . . . . Figure 30: Rich Conference Scenario: Framework Transactions As it can be deduced from the sequence diagram above, the AS, in its business logic, correlates the results of different transactions, addressed to different packages, to implement a more complex Amirante, et al. Expires September 5, 2009 [Page 61] Internet-Draft CFW Call Flow Examples March 2009 conferencing scenario than the Simple Bridging previously described. The framework transaction steps are the following: o Since this is a private conference, the UAC is to be presented with a request for a password, in this case a PIN number; to do so, the AS instructs the MS (A1) to collect a series of DTMF digits from the specified UAC (connectionid=UAC); the request includes both a voice message () and the described digit collection context (); the PIN is assumed to be a 4-digit number, and so the MS has to collect at max 4 digits (maxdigits=4); the DTMF digit buffer must be cleared before collecting (cleardigitbuffer=true) and the UAC can make use of the star key to restart the collection (escapekey=*), e.g. in case it is aware he miswrote any of the digits and wants to start again; o the transaction goes on as usual (A2, A3, A4), with the transaction being extended, and the dialog start being notified in a REPORT terminate; after that, the UAC is actually presented with the voice message, and is subsequently requested to insert the required PIN number; o we assume UAC wrote the correct PIN number (1234), which is reported by the MS to the AS by means of the usual MS-generated CONTROL event (B1); the AS correlates this event to the previously started dialog by checking the referenced dialogid (06d1bac) and acks the event (B2); it then extracts the information it needs from the event (in this case, the digits provided by the MS) from the container (dtmf=1234) and verifies if it is correct; o since the PIN is correct, the AS can proceed towards the next step, that is asking the UAC to state his name, in order to play the recording subsequently on the conference to report the new participant; again, this is done with a request to the IVR package (C1); the AS instructs the MS to play a voice message ("say your name after the beep"), to be followed by a recording of only the audio from the UAC (in stream, media=audio/sendonly, while media=video/inactive); a beep must be played right before the recording starts (beep=true), and the recording must only last 3 seconds (maxtime=3s) since it is only needed as a brief announcement; o without delving again into the details of a recording-related transaction (C2/C3/C4), the AS finally gets an URI to the requested recording (D1, acked in D2); o at this point, the AS attaches the UAC (id1) to the conference (id2) just as explained for Simple Bridging (E1/E2); o finally, to notify the other participants that a new participant has arrived, the AS requests a global announcement on the conference; this is a simple request to the IVR package (F1) just as the ones explained in previous sections, but with a slight difference: the target of the prompt is not a connectionid Amirante, et al. Expires September 5, 2009 [Page 62] Internet-Draft CFW Call Flow Examples March 2009 (a media connection) but the conference itself (conferenceid=6146dd5); as a result of this transaction, the announcement would be played on all the media connections attached to the conference which are allowed to receive media from it; the AS specifically requests two media files to be played: 1. the media file containing the recorded name of the new user as retrieved in D1 ("Simon..."); 2. a pre-recorded media file explaining what happened ("... has joined the conference"); the transaction then takes its usual flow (F2/F3/F4), and the event notifying the end of the announcement (G1, acked in G2) concludes the scenario. A1. AS -> MS (CFW CONTROL, collect) ----------------------------------- CFW 50e56b8d65f9 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 311 A2. AS <- MS (CFW 202) ---------------------- CFW 50e56b8d65f9 202 A3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 50e56b8d65f9 REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Amirante, et al. Expires September 5, 2009 [Page 63] Internet-Draft CFW Call Flow Examples March 2009 Content-Length: 137 A4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 50e56b8d65f9 200 Seq: 1 B1. AS <- MS (CFW CONTROL event) -------------------------------- CFW 166d68a76659 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 272 B2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 166d68a76659 200 C1. AS -> MS (CFW CONTROL, record) ---------------------------------- CFW 61fd484f196e CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 373 C2. AS <- MS (CFW 202) ---------------------- CFW 61fd484f196e 202 C3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 61fd484f196e REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 C4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 61fd484f196e 200 Seq: 1 D1. AS <- MS (CFW CONTROL event) -------------------------------- CFW 3ec13ab96224 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 402 D2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 3ec13ab96224 200 E1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 261d188b63b7 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 120 E2. AS <- MS (CFW 200 OK) ------------------------- CFW 261d188b63b7 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 F1. AS -> MS (CFW CONTROL, play) -------------------------------- CFW 718c30836f38 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 334 Amirante, et al. Expires September 5, 2009 [Page 66] Internet-Draft CFW Call Flow Examples March 2009 F2. AS <- MS (CFW 202) ---------------------- CFW 718c30836f38 202 F3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 718c30836f38 REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 F4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 718c30836f38 200 Seq: 1 G1. AS <- MS (CFW CONTROL event) -------------------------------- CFW 6485194f622f CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 229 Amirante, et al. Expires September 5, 2009 [Page 67] Internet-Draft CFW Call Flow Examples March 2009 G2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 6485194f622f 200 6.3.3. Conferencing with Floor Control [Editors Note: considering a package for floor control is still missing (we started a draft but it's still in an early stage), this section may provide guidelines for BFCP-enabled AS: this would show how floor control in the AS would be "translated" in MediaCtrl directives. Does this sound reasonable?] (Figure not available yet.) Figure 31: Floor Control: Media Perspective (Figure not available yet.) Figure 32: Floor Control: UAC Legs not attached (Figure not available yet.) Figure 33: Floor Control: UAC Legs mixed and attached (Figure not available yet.) Figure 34: Floor Control: Framework Transactions Amirante, et al. Expires September 5, 2009 [Page 68] Internet-Draft CFW Call Flow Examples March 2009 6.3.4. Coaching Scenario Another typical conference-based use case is the so called Coaching Scenario. In such a scenario, a customer (called A in the following example) places a call to a business call center. An agent (B) is assigned to the customer. Besides, a coach (C), unheard from the customer, provides the agent with whispered suggestions about what to say. This scenario is also described in RFC4579 [RFC4579]. As it can be deduced from the scenario description, per-user policies for media mixing and delivery, i.e who can hear what, are very important. The MS must make sure that only the agent can hear the coach's suggestions. Since this is basically a multiparty call (despite what the customer might be thinking), a mixing entity is needed in order to accomplish the scenario requirements. To summarize: o the customer (A) must only hear what the agent (B) says; o the agent (B) must be able to hear both the customer (A) and the coach (C); o the coach (C) must be able to hear both the customer (A), in order to give the right suggestions, and the agent (B), in order to be aware of the whole conversation. From the media and framework perspective, such a scenario can be seen as it is depicted in Figure 35. ************** +-------+ * A=Customer * | UAC | * B=Agent * | C | * C=Coach * +-------+ ************** " ^ C (RTP) " " " " " " A+B (RTP) v " +-------+ A (RTP) +--------+ A+C (RTP) +-------+ | UAC |===================>| Media |===================>| UAC | | A |<===================| Server |<===================| B | +-------+ B (RTP) +--------+ B (RTP) +-------+ Figure 35: Coaching Scenario: Media Perspective From the framework point of view, when the mentioned legs are not attached to anything yet, what appears is described in Figure 36. Amirante, et al. Expires September 5, 2009 [Page 69] Internet-Draft CFW Call Flow Examples March 2009 MS +---------------------------+ | | UAC A | | UAC B o.....<<.......x x-------<<-----o o----->>-------x x.......>>.....o | | | | | | | | | xx | | .| + +------------v^-------------+ v^ .| .| oo UAC C Figure 36: Coaching Scenario: UAC Legs not attached What the scenario should look like is instead depicted in Figure 37. The customer receives media directly from the agent (recvonly), while all the three involved participants contribute to a hidden conference: of course the customer is not allowed to receive the mixed flows from the conference (sendonly), unlike the agent and the coach which must both be aware of the whole conversation (sendrecv). Amirante, et al. Expires September 5, 2009 [Page 70] Internet-Draft CFW Call Flow Examples March 2009 MS +---------------------------+ | | UAC A | | UAC B o-----<<-------+----<<----+----<<----+-------<<-----o o----->>-------+ | +------->>-----o | | v ^ | | +~~~~~~~>[##]::::>::::+ | | v^ | | || | | ++ | | :| + +------------v^-------------+ v^ :| :| oo UAC C Figure 37: Coaching Scenario: UAC Legs mixed and attached In the framework this can be achieved by means of the mixer control package, which, as already explained in previous sections, can be exploited whenever mixing and joining entities are needed. The needed steps can be summarized in the following list: 1. first of all, a hidden conference is created; 2. then, all the three participants are attached to it, each with a custom mixing policy, specifically: * the customer (A) as 'sendonly'; * the agent (B) as 'sendrecv'; * the coach (C) as 'sendrecv' and with a -3dB gain to halve the volume of its own contribution (so that the agent actually hears the customer louder, and the coach whispering); 3. finally, the customer is joined to the agent as a passive receiver (recvonly). A sequence diagram of such a sequence of transactions is depicted in Figure 38: A B C AS MS | | | | | | | | | A1. CONTROL (create conference) | | | | |++++++++++++++++++++++++++++++++>>| | | | | |--+ create Amirante, et al. Expires September 5, 2009 [Page 71] Internet-Draft CFW Call Flow Examples March 2009 | | | | | | conf and | | | | A2. 200 OK (conferenceid=Y) |<-+ its ID | | | |<<++++++++++++++++++++++++++++++++| | | | | | | | | | B1. CONTROL (join A-->confY) | | | | |++++++++++++++++++++++++++++++++>>| | | | | |--+ join A | | | | | | & confY | | | | B2. 200 OK |<-+ sendonly | | | |<<++++++++++++++++++++++++++++++++| | | | | | |######################################################>>| | Customer A is mixed (sendonly) in the conference | |######################################################>>| | | | | | | | | | C1. CONTROL (join B<->confY) | | | | |++++++++++++++++++++++++++++++++>>| | | | | |--+ join B | | | | | | & confY | | | | C2. 200 OK |<-+ sendrecv | | | |<<++++++++++++++++++++++++++++++++| | | | | | | |<<#############################################>>| | | Agent B is mixed (sendrecv) in the conference | | |<##############################################>>| | | | | | | | | | D1. CONTROL (join C<->confY) | | | | |++++++++++++++++++++++++++++++++>>| | | | | |--+ join C | | | | | | & confY | | | | D2. 200 OK |<-+ sendrecv | | | |<<++++++++++++++++++++++++++++++++| | | | | | | | |<<######################################>>| | | | Coach C is mixed (sendrecv) as well | | | |<<######################################>>| | | | | | | | | | E1. CONTROL (join A<--B) | | | | |++++++++++++++++++++++++++++++++>>| | | | | |--+ join | | | | | | A & B | | | | E2. 200 OK |<-+ recvonly | | | |<<++++++++++++++++++++++++++++++++| | | | | | |<<######################################################| | Finally, Customer A is joined (recvonly) to Agent B | |<<######################################################| | | | | | Amirante, et al. Expires September 5, 2009 [Page 72] Internet-Draft CFW Call Flow Examples March 2009 . . . . . . . . . . Figure 38: Coaching Scenario: Framework Transactions o First of all, the AS creates a new hidden conference by means of a 'createconference' request (A1); this conference is properly configured according to the use it is assigned to, that is to mix all the involved parties accordingly; since only three participants will be joined to it, 'reserved-talkers' is set to 3; 'reserved-listeners', instead, is set to 2, since only the agent and the coach must receive a mix, while the customer must be unaware of the coach; finally, the video layout is set to dual- view for the same reason, since only the customer and the agent must appear in the mix; o the MS notifies the successful creation of the new conference in a 200 framework message (A2); the identifier assigned to the conference, which will be used in subsequent requests addressed to it, is 1df080e; o now that the conference has been created, the AS joins the three actors to it with different policies, namely: (i) the customer A is joined as sendonly to the conference (B1), (ii) the agent B is joined as sendrecv to the conference (C1) and (iii) the coach is joined as sendrecv (but audio only) to the conference and with a lower volume (D1); the custom policies are enforced by means of properly constructed elements; o the MS takes care of the requests and acks them (B2, C2, D2); at this point, the conference will receive media from all the actors, but only provide the agent and the coach with the resulting mix; o to complete the scenario, the AS joins the customer A with the agent B directly as recvonly (E1); the aim of this request is to provide customer A with media too, namely the media contributed by agent B; this way, customer A is unaware of the fact that its media are accessed by coach C by means of the hidden mixer; o the MS takes care of this request too and acks it (E2), concluding the scenario. A1. AS -> MS (CFW CONTROL, createconference) -------------------------------------------- CFW 238e1f2946e8 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 329 Amirante, et al. Expires September 5, 2009 [Page 73] Internet-Draft CFW Call Flow Examples March 2009 dual-view A2. AS <- MS (CFW 200 OK) ------------------------- CFW 238e1f2946e8 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 151 B1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 2eb141f241b7 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 226 B2. AS <- MS (CFW 200 OK) ------------------------- CFW 2eb141f241b7 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 Amirante, et al. Expires September 5, 2009 [Page 74] Internet-Draft CFW Call Flow Examples March 2009 C1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 515f007c5bd0 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 122 C2. AS <- MS (CFW 200 OK) ------------------------- CFW 515f007c5bd0 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 D1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 0216231b1f16 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 221 D2. AS <- MS (CFW 200 OK) ------------------------- CFW 0216231b1f16 200 Timeout: 10 Content-Type: application/msc-mixer+xml Amirante, et al. Expires September 5, 2009 [Page 75] Internet-Draft CFW Call Flow Examples March 2009 Content-Length: 125 E1. AS -> MS (CFW CONTROL, join) -------------------------------- CFW 140e0f763352 CONTROL Control-Package: msc-mixer Content-Type: application/msc-mixer+xml Content-Length: 236 E2. AS <- MS (CFW 200 OK) ------------------------- CFW 140e0f763352 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 125 6.3.5. Sidebars [Editors Note: the concept of sidebars is still a bit unclear within the XCON WG (see Data Model and CCMP), and so a bit of clarification is needed before attempting at writing a paragraph of related guidelines in here. Any comments/suggestions in that sense?] (Figure not available yet.) Figure 39: Sidebars: Media Perspective Amirante, et al. Expires September 5, 2009 [Page 76] Internet-Draft CFW Call Flow Examples March 2009 (Figure not available yet.) Figure 40: Sidebars: UAC Legs not attached (Figure not available yet.) Figure 41: Sidebars: UAC Legs mixed and attached (Figure not available yet). Figure 42: Sidebars: Framework Transactions 6.4. Additional Scenarios This section includes additional scenarios that can be of interest when dealing with AS<->MS flows. The aim of the following subsections is to present the use of peculiar features provided by the IVR package, specifically variable announcements, VCR prompts, parallel playback, recurring dialogs and custom grammars. To describe how call flows involving such features might happen, three sample scenarios have been chosen: 1. Voice Mail (variable announcements for digits, VCR controls); 2. Current Time (variable announcements for date and time, parallel playback). 3. DTMF-driven Conference Manipulation (recurring dialogs, custom grammars). 6.4.1. Voice Mail An application that typically makes use of the services an MS can provide is Voice Mail. In fact, while it is clear that many of its features are part of the application logic (e.g. the mapping of a URI with a specific user's voice mailbox, the list of messages and their properties, and so on), the actual media work is accomplished through the MS. Features needed by a VoiceMail application include the ability to record a stream and play it back anytime later, give verbose announcements regarding the status of the application, control the playout of recorded messages by means of VCR controls and so on, all features which are supported by the MS through the IVR package. Amirante, et al. Expires September 5, 2009 [Page 77] Internet-Draft CFW Call Flow Examples March 2009 Without delving into the details of a full VoiceMail application and all its possible use cases, this section will cover a specific scenario, trying to deal with as many interactions as possible that may happen between the AS and the MS in such a context. The covered scenario, depicted as a sequence diagram in Figure 43, will be the following: 1. The UAC INVITEs a URI associated with his mailbox, and the AS follows the already explained procedure to have the UAC negotiate a new media session with the MS; 2. The UAC is first prompted with an announcement giving him the amount of available new messages in the mailbox; after that, the UAC can choose which message to access by sending a DTMF tone; 3. The UAC is then presented with a VCR controlled announcement, in which the chosen received mail is played back to him; VCR controls allow him to navigate through the prompt. This is a quite oversimplified scenario, considering it doesn't even allow the UAC to delete old messages or organize them, but just to choose which received message to play. Nevertheless, it gives us the chance to deal with variable announcements and VCR controls, two typical features a Voice Mail application would almost always take advantage of. Besides, other features a Voice Mail application would rely upon (e.g. recording streams, event driven IVR menus and so on) have aready been introduced in previous sections, and so representing them would be redundant. This means the presented call flows assume that some messages have already been recorded, and that they are available at reachable locations. The example also assumes that the AS has placed the recordings in its own storage facilities, considering it is not safe to rely upon the internal MS storage which is likely to be temporary. UAC AS MS | | | | | A1. CONTROL (play variables and | | | collect the user's choice) | | |++++++++++++++++++++++++++++++++>>| | | A2. 202 | | |<<++++++++++++++++++++++++++++++++| prepare & | | |--+ start | | | | the | | A3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | A4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | Amirante, et al. Expires September 5, 2009 [Page 78] Internet-Draft CFW Call Flow Examples March 2009 |<<########################################################| | "You have five messages ..." | |<<########################################################| | | | | | B1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | B2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | | | C1. CONTROL (VCR for chosen msg) | | |++++++++++++++++++++++++++++++++>>| | | C2. 202 | | |<<++++++++++++++++++++++++++++++++| prepare & | | |--+ start | | | | the | | C3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | C4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | "Hi there, I tried to call you but..." |--+ |<<########################################################| | handle | | | | VCR- |########################################################>>| | driven | The UAC controls the playout using DTMF | | (DTMF) |########################################################>>| |playout | | |<-+ | | D1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | D2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | . . . . (other events are received in the meanwhile) | . . . | | E1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | E2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | . . . . . . Figure 43: Voice Mail: Framework Transactions The framework transaction steps are described in the following: Amirante, et al. Expires September 5, 2009 [Page 79] Internet-Draft CFW Call Flow Examples March 2009 o The first transaction (A1) is addressed to the IVR package (msc- ivr); it is basically a 'promptandcollect' dialog, but with a slight difference: some of the prompts to play are actual audio files, for which a URI is provided (media loc="xxx"), while others are so-called 'variable' prompts; these 'variable' prompts are actually constructed by the MS itself according to the directives provided by the AS; in this example, this is the sequence of prompts that is requested by the AS: 1. play a wav file ("you have..."); 2. play a digit ("five..."), by building it (variable: digit=5); 3. play a wav file ("messages..."); a DTMF collection is requested as well () to be taken after the prompts have been played; the AS is only interested in a single digit (maxdigits=1); o the transaction is extended by the MS (A2) and, in case everything works fine (i.e. the MS retrieved all the audio files and successfully built the variable ones), the dialog is started; its start is reported, together with the associated identifier (5db01f4) to the AS in a terminating REPORT message (A3); o the AS acks the REPORT (A4), and waits for the dialog to end in order to retrieve the results it is interested in (in this case, the DTMF tone the UAC chooses, since it will affect which message will have to be played subsequently); o the UAC hears the prompts and chooses a message to play; in this example, he wants to listen to the first message, and so digits 1; the MS intercepts this tone, and notifies it to the AS in a newly created CONTROL event message (B1); this CONTROL includes information about how each single requested operation ended ( and ); specifically, the event states that the prompt ended normally (termmode=completed) and that the subsequently collected tone is 1 (dtmf=1); the AS acks the event (B2), since the dialogid provided in the message is the same as the one of the previously started dialog; o at this point, the AS makes use of the value retrieved from the event to proceed in its business logic; it decides to present the UAC with a VCR-controllable playout of the requested message; this is done with a new request to the IVR package (C1), which contains two operations: to address the media file to play (an old recording), and to instruct the MS about how the playout of this media file shall be controlled via DTMF tones provided by the UAC (in this example, different DTMF digits are associated with different actions, e.g. pause/resume, fast forward, rewind and so on); besides, the AS also subscribes to DTMF events related to this control operation (matchmode=control), which means that the MS is to trigger an event anytime a DTMF associated with a control operation (e.g. 7=pause) is intercepted; Amirante, et al. Expires September 5, 2009 [Page 80] Internet-Draft CFW Call Flow Examples March 2009 o the MS prepares the dialog, notifying about the transaction being extended (C2) and, when the playout starts, notifies it in a terminating REPORT (C3), which is acked by the AS (C4); at this point, the UAC is presented with the prompt, and can make use of DTMF digits to control the playback; o as explained previously, any DTMF associated with a VCR operation is then reported to the AS, together with a timestamp stating when the event happened; an example is provided (D1) in which the UAC pressed the fast forward key (6) at a specific time; of course, as for any other MS-generated event, the AS acks it (D2); o when the playback ends (whether because the media reached its termination, or because any other interruption occurred), the MS triggers a concluding event with information about the whole dialog (E1); this event, besides including information about the prompt itself (), also includes information related to the VCR operations (), that is, all the VCR controls the UAC made use of (in the example fastforward/rewind/pause/ resume) and when it happened; the final ack by the AS (E2) concludes the scenario. A1. AS -> MS (CFW CONTROL, play and collect) -------------------------------------------- CFW 2f931de22820 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 429 Amirante, et al. Expires September 5, 2009 [Page 81] Internet-Draft CFW Call Flow Examples March 2009 A2. AS <- MS (CFW 202) ---------------------- CFW 2f931de22820 202 A3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 2f931de22820 REPORT Seq: 1 Status: terminate Timeout: 15 Content-Type: application/msc-ivr+xml Content-Length: 137 A4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 2f931de22820 200 Seq: 1 B1. AS <- MS (CFW CONTROL event) -------------------------------- CFW 7c97adc41b3e CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 270 B2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 7c97adc41b3e 200 C1. AS -> MS (CFW CONTROL, VCR) Amirante, et al. Expires September 5, 2009 [Page 82] Internet-Draft CFW Call Flow Examples March 2009 ------------------------------- CFW 3140c24614bb CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 423 C2. AS <- MS (CFW 202) ---------------------- CFW 3140c24614bb 202 C3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 3140c24614bb REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 C4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 3140c24614bb 200 Seq: 1 Amirante, et al. Expires September 5, 2009 [Page 83] Internet-Draft CFW Call Flow Examples March 2009 D1. AS <- MS (CFW CONTROL event, dtmfnotify) -------------------------------------------- CFW 361840da0581 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 179 D2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 361840da0581 200 [..] The other VCR DTMF notifications are skipped for brevity [..] E1. AS <- MS (CFW CONTROL event, dialogexit) -------------------------------------------- CFW 3ffab81c21e9 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 485 E2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 3ffab81c21e9 200 Amirante, et al. Expires September 5, 2009 [Page 84] Internet-Draft CFW Call Flow Examples March 2009 6.4.2. Current Time An interesting scenario to realize with the help of the MS provided features is what is typically called 'Current Time'. A UAC calls a URI, which presents the caller with the current date and time. As it can easily be deduced by the very nature of the application, variable announcements play an important role in this scenario. In fact, rather than having the AS build different framework messages according to the current time to build an announcement, it is much easier to rely upon the variable announcements mechanism provided by the IVR package, which includes ways to deal with dates and times in several fashions. To make the scenario more interesting and have it cover more functionality, the application is also assumed to have a background music played during the announcement. Considering that most of the announcements will be variable, a means is needed to have more streams played in parallel on the same connection. This can be achieved in two different ways: 1. two separate and different dialogs, playing respectively the variable announcements and the background track; 2. a single dialog implementing a parallel playback. The first approach assumes the available MS implements implicit mixing, which may or may not be supported, since it's a recommended feature but not a mandatory one. The second approach instead assumes the MS implements support for more streams of the same media type (in this case audio) in the same dialog, which, exactly as implicit mixing, is not to be given for granted. Considering the first approach is quite straightforward to understand, the presented scenario makes use of the second one, and assumes the available MS supports parallel playback of more audio tracks within the context of the same dialog. That said, the covered scenario, depicted as a sequence diagram in Figure 44, will be the following: 1. The UAC INVITEs a URI associated with the Current Time application, and the AS follows the already explained procedure to have the UAC negotiate a new media session with the MS; 2. The UAC is presented with an announcement including: (i) a voice stating the current date and time; (ii) a background music track; (iii) a mute background video track. Amirante, et al. Expires September 5, 2009 [Page 85] Internet-Draft CFW Call Flow Examples March 2009 UAC AS MS | | | | | A1. CONTROL (play variables) | | |++++++++++++++++++++++++++++++++>>| | | A2. 202 | | |<<++++++++++++++++++++++++++++++++| prepare & | | |--+ start | | | | the | | A3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++| | | A4. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | |<<########################################################| | "16th of december 2008, 5:31 PM..." | |<<########################################################| | | | | | B1. CONTROL () | | |<<++++++++++++++++++++++++++++++++| | | B2. 200 OK | | |++++++++++++++++++++++++++++++++>>| | | | . . . . . . Figure 44: Current Time: Framework Transactions The framework transaction steps are described in the following: o The first transaction (A1) is addressed to the IVR package (msc- ivr); it is basically a 'playannouncement' dialog, but, unlike all the scenarios presented so far, it includes directives for a parallel playback, as indicated by the 'par' element; there are three flows to play in parallel: * a sequence ('seq') of variable and static announcements (the actual time and date); * a music track ('media=music.wav') to be played in background at a lower volume (soundLevel=50%); * a mute background video track (media=clock.mpg). The global announcement ends when the longest of the three parallel steps ends (endsync=last); this means that, if one of the steps ends before the others, the step is muted for the rest of the playback. About the series of static and variable announcements, in this example this is requested by the AS: * play a wav file ("Tuesday..."); Amirante, et al. Expires September 5, 2009 [Page 86] Internet-Draft CFW Call Flow Examples March 2009 * play a date ("16th of december 2008..."), by building it (variable: date with a ymd=year/month/day format); * play a time ("5:31 PM..."), by building it (variable: time with a t12=12 hour day format, am/pm). o the transaction is extended by the MS (A2) and, in case everything went fine (i.e. the MS retrieved all the audio files and successfully built the variable ones, and it supports parallel playback as requested), the dialog is started; its start is reported, together with the associated identifier (415719e) to the AS in a terminating REPORT message (A3); o the AS acks the REPORT (A4), and waits for the dialog to end in order to conclude the application, or proceed to further steps if required by the application itself; o when the last of the three parallel announcements ends, the dialog terminates, and an event (B1) is triggered to the AS with the relevant information (promptinfo); the AS acks (B2) and terminates the scenario. A1. AS -> MS (CFW CONTROL, play) -------------------------------- CFW 0c7680191bd2 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 506 A2. AS <- MS (CFW 202) Amirante, et al. Expires September 5, 2009 [Page 87] Internet-Draft CFW Call Flow Examples March 2009 ---------------------- CFW 0c7680191bd2 202 A3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 0c7680191bd2 REPORT Seq: 1 Status: terminate Timeout: 15 Content-Type: application/msc-ivr+xml Content-Length: 137 A4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 0c7680191bd2 200 Seq: 1 B1. AS <- MS (CFW CONTROL event) -------------------------------- CFW 4481ca0c4fca CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 229 B2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 4481ca0c4fca 200 Amirante, et al. Expires September 5, 2009 [Page 88] Internet-Draft CFW Call Flow Examples March 2009 6.4.3. DTMF-driven Conference Manipulation To complete the scenarios presented in Section 6.3, this section deals with how the AS can make use of the MS in order to detect DTMF tones from conference participants, and take actions on the conference accordingly. A typical example is when participants in a conference are provided with specific codes to: o mute/unmute themselves in the conference; o change their volume in the conference, or the volume of the conference itself; o change the video layout in the conference, if allowed; o kick abusing users from the conference; and so on. To achieve all this, the simpliest thing an AS can do is to prepare a recurring DTMF collection for each participant with specific grammars to match. In case the collected tones match the grammar, the MS would notify them to the AS, and start the collection again. Upon receival of events, the AS would in turn originate the proper related request, e.g. a on the participant's stream with the conference. This is made possible by three features provided by the IVR package: 1. the 'repeatCount' attribute; 2. the subscription mechanism; 3. the Speech Recognition Grammar Specification (SRGS). The first allows for recurring instances of the same dialog without the need of additional requests upon completion of the dialog itself. In fact, the 'repeatCount' attribute indicates how many times the dialog has to be repeated: when the attribute has the value 0, it means that the dialog has to be repeated indefinitely, meaning that it's up to the AS to destroy it by means of a request when the dialog isn't needed anymore. The second, instead, allows the AS to subscribe to events related to the IVR package without waiting for the dialog to end, e.g. matching DTMF collections in this case. The last, finally, allows for custom matching grammars to be specified: this way, only a subset of the possible DTMF strings can be specified, so that only the matches the AS is interested in are reported. Different grammars other than SRGS may be supported by the MS, which achieve the same result: anyway, this document will only describe the use of an SRGS grammar, since support for SRGS is mandated in the IVR package specification. To identify a single sample scenario, we assume a participant has already successfully joined a conference, e.g. as detailed in Figure 30. Besides, we assume the following codes are to be provided within the conference to participants in order to let them take Amirante, et al. Expires September 5, 2009 [Page 89] Internet-Draft CFW Call Flow Examples March 2009 advantage of advanced features: 1. *6 to mute/unmute themselves (on/off trigger); 2. *1 to lower their own volume in the conference, and *3 to raise it; 3. *7 to lower the volume of the conference stream they are receiving, and *9 to raise it; 4. *0 to leave the conference. This means that six different codes are supported, and are to be matched in the requested DTMF collection. All other codes are collected by the MS, but discarded, and no event is triggered to the AS. Considering all the codes have the '*' (star) DTMF code in common, the following is an example of an SRGS grammar that may be used in the request by the AS: 0 1 3 6 7 9 * As it can be deduced by looking at the grammar, the presented SRGS XML code specifies exactly the requirements for the collections to match: the rule is to match any string which has a star ('*') followed by just one of any supported digit (0, 1, 3, 6, 7, 9). Such grammar, as stated in the IVR package specification, may be provided either inline in the request itself or referenced externally by means of the 'src' attribute. In the scenario example, we'll put it inline, but an external reference to the same document would achieve exactly the same result. Amirante, et al. Expires September 5, 2009 [Page 90] Internet-Draft CFW Call Flow Examples March 2009 Figure 45 shows how the AS might request the recurring collection for a UAC: as already anticipated before, the example assumes the UAC is already a participant in the conference. UAC AS MS | | | | | A1. CONTROL (recurring collection) | | |++++++++++++++++++++++++++++++++++++>>| | | A2. 202 | | |<<++++++++++++++++++++++++++++++++++++| | | |--+ start | | | | the | | A3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++++++| | | A4. 200 OK | | |++++++++++++++++++++++++++++++++++++>>| | | | |########################################################>>| | Recurring DTMF digit collection starts |--+ get |########################################################>>| | DTMF | | |<-+ digits | | B1. CONTROL (dtmfinfo=*1) | | |<<++++++++++++++++++++++++++++++++++++| | | B2. 200 OK |--+ get | |++++++++++++++++++++++++++++++++++++>>| | DTMF | | |<-+ ditigs | | C1. CONTROL (modifyjoin UAC1-->conf) | | |++++++++++++++++++++++++++++++++++++>>| | | |--+ modify | | | | UAC | | C2. 200 OK |<-+ volume | |<<++++++++++++++++++++++++++++++++++++| | | | |########################################################>>| | Volume of UAC in conference is lowered | |########################################################>>| | | | | | D1. CONTROL (dtmfinfo=*9) | | |<<++++++++++++++++++++++++++++++++++++| | | D2. 200 OK |--+ get | |++++++++++++++++++++++++++++++++++++>>| | DTMF | | |<-+ ditigs | | E1. CONTROL (modifyjoin UAC1<--conf) | | |++++++++++++++++++++++++++++++++++++>>| | | |--+ modify | | | | conf Amirante, et al. Expires September 5, 2009 [Page 91] Internet-Draft CFW Call Flow Examples March 2009 | | E2. 200 OK |<-+ volume | |<<++++++++++++++++++++++++++++++++++++| | | | |<<########################################################| | Now UAC can hear the conference mix at a higher volume | |<<########################################################| | | | | | F1. CONTROL (dtmfinfo=*6) | | |<<++++++++++++++++++++++++++++++++++++| | | F2. 200 OK |--+ get | |++++++++++++++++++++++++++++++++++++>>| | DTMF | | |<-+ ditigs | | G1. CONTROL (modifyjoin UAC1-->conf) | | |++++++++++++++++++++++++++++++++++++>>| | | |--+ mute | | | | UAC in | | G2. 200 OK |<-+ conf | |<<++++++++++++++++++++++++++++++++++++| | | | |########################################################>>| | UAC is now muted in the conference | |########################################################>>| | | | | | H1. CONTROL (dtmfinfo=*0) | | |<<++++++++++++++++++++++++++++++++++++| | | H2. 200 OK |--+ get | |++++++++++++++++++++++++++++++++++++>>| | DTMF | | |<-+ ditigs | | I1. CONTROL (destroy DTMF dialog) | | |++++++++++++++++++++++++++++++++++++>>| | | I2. 202 | | |<<++++++++++++++++++++++++++++++++++++| | | |--+ delete | | | | the | | I3. REPORT (terminate) |<-+ dialog | |<<++++++++++++++++++++++++++++++++++++| (DTMF | | I4. 200 OK |collection | |++++++++++++++++++++++++++++++++++++>>| stops) | | | | | J1. CONTROL (dialogexit) | | |<<++++++++++++++++++++++++++++++++++++| | | J2. 200 OK | | |++++++++++++++++++++++++++++++++++++>>| | | | |########################################################>>| | No more tones from UAC are collected | |########################################################>>| | | | Amirante, et al. Expires September 5, 2009 [Page 92] Internet-Draft CFW Call Flow Examples March 2009 | | K1. CONTROL (unjoin UAC1<-X->conf) | | |++++++++++++++++++++++++++++++++++++>>| | | |--+ unjoin | | | | UAC & | | K2. 200 OK |<-+ conf | |<<++++++++++++++++++++++++++++++++++++| | | | | | L1. CONTROL (notify-unjoin) | | |<<++++++++++++++++++++++++++++++++++++| | | L2. 200 OK | | |++++++++++++++++++++++++++++++++++++>>| | | | . . . . . . Figure 45: DTMF-driven Conference Manipulation: Framework Transactions As it can be deduced from the sequence diagram above, the AS, in its business logic, correlates the results of different transactions, addressed to different packages, to implement a more complex conferencing scenario: in fact, 'dtmfnotify' events are used to take actions according to the purpose the DTMF codes are meant for. The framework transaction steps are the following: o The UAC is already in the conference, and so the AS starts a recurring collect with a grammar to match; this is done by placing a CONTROL request addressed to the IVR package (A1); the operation to implement is a , and we are only interested in two- digits DTMF strings (maxdigits); the AS is not interested in a DTMF terminator (termchar is set to a non-conventional DTMF character), and the DTMF escape key is set to '#' (the default is '*', which would conflict with the code syntax for the conference, and so needs to be changed); a custom SRGS grammar is provided inline ( with mode=dtmf); the whole dialog is to be repeated indefinitely (dialog has repeatCount=0), and the AS wants to be notified when matching collections occur (dtmfsub with matchmode=collect); o the request is extended by the MS as already explained in previous sections (A2-4), and then successfully started (dialogid=01d1b38); this means the MS has started collecting DTMF tones from UAC; o the MS collects a matching DTMF string from UAC (*1); since the AS subscribed to this kind of event, a CONTROL event notification (dtmfnotify) is triggered by the MS (B1), including the collected tones; since the dialog is recurring, the MS immediately restarts the collection; Amirante, et al. Expires September 5, 2009 [Page 93] Internet-Draft CFW Call Flow Examples March 2009 o the AS acks the event (B2), and in its business logic understands that the code '*1' means that the UAC wants its own volume to be lowered in the conference mix; the AS is able to associate the event with the right UAC by referring to the attached dialogid (01d1b38); it then acts accordingly, by sending a (C1) which does exactly this: the provided child element instructs the MS into modifying the volume of the UAC-->conference audio flow (setgain=-3dB sendonly); notice how the request also includes directives upon the inverse direction; this verbose approach is needed, since otherwise the MS would not only change the volume in the requested direction, but also disable the media flow in the other direction; having a proper addressing the UAC<--conf media flow as well ensures that this doesn't happen; o the MS successfully enforces the requested operation (C2), changing the volume; o a new matching DTMF string from UAC is collected (*9); as before, an event is triggered to the AS (D1); o the AS acks the event (D2), and matches the new code ('*9') with its related operation (raise the volume of the conference mix for UAC), taking the proper action; a different is sent (E1) with the new instructions (setgain=+3dB recvonly); o the MS successfully enforces this requested operation as well (E2), changing the volume in the specified direction; again, a for the inverse direction is provided again, which basically confirms the directives of (C1); o at this point, a further matching DTMF string from UAC is collected (*6), and sent to the AS (F1); o after the rquired ack (F2), the AS reacts by implementing the action associated with the new code ('*6'), by which UAC requested to be muted within the conference; a new is sent (G1) with a properly constructed payload (setstate=mute sendonly), and the MS enforces it (G2); o a last (in the scenario) matching DTMF string is collected by the MS (*0); as with all the previous codes, this string is notified to the AS (H1); o the AS acks the event (H2), and understands the UAC wants to leave the conference now (since the code is *0); this means that a series of actions must be taken, namely: * actually stopping the recurring collection, since it's not needed anymore; * unjoin UAC from the conference it is in; * additional operations might be considered, e.g. a global announcement stating UAC is leaving, but are left out for the sake of conciseness); the former is accomplished by means of a request (I1) to the IVR package (dialogid=01d1b38); the latter by means of an 'unjoin' request (K1) to the Mixer package instead; Amirante, et al. Expires September 5, 2009 [Page 94] Internet-Draft CFW Call Flow Examples March 2009 o the request is extended by the MS (I2-4), and the dialog is terminated successfully; as soon as the dialog has actually been terminated, a 'dialogexit' event is triggered as well to the AS (J1); this event has no report upon the result of the last iteration (since the dialog was terminated abruptly with an immediate=true) and is acked by the AS (J2) to finally complete the dialog lifetime; o the request, instead, is immediately enforced (K2); as a consequence of the unjoin operation, an 'unjoin-notify' event notification is triggered by the MS (L1) to confirm to the AS that the requested entities are not attached to each other anymore; the status in the event is set to 0 which, as stated in the specification, means the join has been terminated by an request; the ack of the AS (L2) concludes this scenario. A1. AS -> MS (CFW CONTROL, recurring collect with grammar) ---------------------------------------------------------- CFW 238e1f2946e8 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 809 0 1 3 6 7 9 *3 * Amirante, et al. Expires September 5, 2009 [Page 95] Internet-Draft CFW Call Flow Examples March 2009 A2. AS <- MS (CFW 202) ---------------------- CFW 238e1f2946e8 202 Timeout: 10 A3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 238e1f2946e8 REPORT Seq: 1 Status: terminate Timeout: 25 Content-Type: application/msc-ivr+xml Content-Length: 137 A4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 238e1f2946e8 200 Seq: 1 B1. AS <- MS (CFW CONTROL dtmfnotify event) ------------------------------------------- CFW 1dd62e043c00 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 180 Amirante, et al. Expires September 5, 2009 [Page 96] Internet-Draft CFW Call Flow Examples March 2009 B2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 1dd62e043c00 200 C1. AS -> MS (CFW CONTROL, modifyjoin with setgain) --------------------------------------------------- CFW 0216231b1f16 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 290 C2. AS <- MS (CFW 200 OK) ------------------------- CFW 0216231b1f16 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 123 D1. AS <- MS (CFW CONTROL dtmfnotify event) ------------------------------------------- CFW 4d674b3e0862 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 180 Amirante, et al. Expires September 5, 2009 [Page 97] Internet-Draft CFW Call Flow Examples March 2009 D2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 4d674b3e0862 200 E1. AS -> MS (CFW CONTROL, modifyjoin with setgain) --------------------------------------------------- CFW 140e0f763352 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 342 E2. AS <- MS (CFW 200 OK) ------------------------- CFW 140e0f763352 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 123 F1. AS <- MS (CFW CONTROL dtmfnotify event) ------------------------------------------- CFW 478ed6f1775b CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Amirante, et al. Expires September 5, 2009 [Page 98] Internet-Draft CFW Call Flow Examples March 2009 Content-Length: 180 F2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 478ed6f1775b 200 G1. AS -> MS (CFW CONTROL, modifyjoin with setstate) ---------------------------------------------------- CFW 7fdcc2331bef CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 345 G2. AS <- MS (CFW 200 OK) ------------------------- CFW 7fdcc2331bef 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 123 H1. AS <- MS (CFW CONTROL dtmfnotify event) ------------------------------------------- Amirante, et al. Expires September 5, 2009 [Page 99] Internet-Draft CFW Call Flow Examples March 2009 CFW 750b917a5d4a CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 180 H2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 750b917a5d4a 200 I1. AS -> MS (CFW CONTROL, dialogterminate) ------------------------------------------- CFW 515f007c5bd0 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 128 I2. AS <- MS (CFW 202) ---------------------- CFW 515f007c5bd0 202 Timeout: 10 I3. AS <- MS (CFW REPORT terminate) ----------------------------------- CFW 515f007c5bd0 REPORT Seq: 1 Status: terminate Timeout: 10 Content-Type: application/msc-ivr+xml Content-Length: 140 Amirante, et al. Expires September 5, 2009 [Page 100] Internet-Draft CFW Call Flow Examples March 2009 I4. AS -> MS (CFW 200, ACK to 'REPORT terminate') ------------------------------------------------- CFW 515f007c5bd0 200 Seq: 1 J1. AS <- MS (CFW CONTROL dialogexit event) ------------------------------------------- CFW 76adc41122c1 CONTROL Control-Package: msc-ivr/1.0 Content-Type: application/msc-ivr+xml Content-Length: 155 J2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 76adc41122c1 200 K1. AS -> MS (CFW CONTROL, unjoin) ---------------------------------- CFW 4e6afb6625e4 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 127 K2. AS <- MS (CFW 200 OK) ------------------------- CFW 4e6afb6625e4 200 Timeout: 10 Content-Type: application/msc-mixer+xml Content-Length: 122 Amirante, et al. Expires September 5, 2009 [Page 101] Internet-Draft CFW Call Flow Examples March 2009 L1. AS <- MS (CFW CONTROL unjoin-notify event) ---------------------------------------------- CFW 577696293504 CONTROL Control-Package: msc-mixer/1.0 Content-Type: application/msc-mixer+xml Content-Length: 157 L2. AS -> MS (CFW 200, ACK to 'CONTROL event') ---------------------------------------------- CFW 577696293504 200 7. Security Considerations [Editors Note: the MediaCtrl drafts provide detailed indications for what concerns security within the context of the AS-MS interaction. The security section in this document may provide examples following those indications, e.g. two different AS placing auditing requests on the same MS, what happens when AS1 attempts to access/manipulate resources owned by AS2 or viceversa, and so on. What do you think about it?] 8. Acknowledgements The authors would like to thank... 9. References [RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Amirante, et al. Expires September 5, 2009 [Page 102] Internet-Draft CFW Call Flow Examples March 2009 [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. [RFC3725] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. Camarillo, "Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP)", BCP 85, RFC 3725, April 2004. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [RFC4574] Levin, O. and G. Camarillo, "The Session Description Protocol (SDP) Label Attribute", RFC 4574, August 2006. [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in the Session Description Protocol (SDP)", RFC 4145, September 2005. [RFC4579] Johnston, A. and O. Levin, "Session Initiation Protocol (SIP) Call Control - Conferencing for User Agents", BCP 119, RFC 4579, August 2006. [RFC5167] Dolly, M. and R. Even, "Media Server Control Protocol Requirements", RFC 5167, March 2008. [I-D.ietf-mediactrl-architecture] Melanchuk, T., "An Architectural Framework for Media Server Control", draft-ietf-mediactrl-architecture-04 (work in progress), November 2008. [I-D.ietf-mediactrl-sip-control-framework] Boulton, C., Melanchuk, T., and S. McGlashan, "Media Control Channel Framework", draft-ietf-mediactrl-sip-control-framework-10 (work in progress), February 2009. [I-D.boulton-mmusic-sdp-control-package-attribute] Amirante, et al. Expires September 5, 2009 [Page 103] Internet-Draft CFW Call Flow Examples March 2009 Boulton, C., "A Session Description Protocol (SDP) Control Package Attribute", draft-boulton-mmusic-sdp-control-package-attribute-03 (work in progress), August 2008. [I-D.ietf-mediactrl-ivr-control-package] McGlashan, S., Melanchuk, T., and C. Boulton, "An Interactive Voice Response (IVR) Control Package for the Media Control Channel Framework", draft-ietf-mediactrl-ivr-control-package-06 (work in progress), March 2009. [I-D.ietf-mediactrl-mixer-control-package] McGlashan, S., Melanchuk, T., and C. Boulton, "A Mixer Control Package for the Media Control Channel Framework", draft-ietf-mediactrl-mixer-control-package-05 (work in progress), February 2009. [I-D.miniero-bfcp-control-package] Miniero, L., Romano, S., Even, R., and S. McGlashan, "A Binary Floor Control Protocol (BFCP) Control Package for the Media Control Channel Framework", draft-miniero-bfcp-control-package-01 (work in progress), July 2008. Authors' Addresses Alessandro Amirante University of Napoli Via Claudio 21 Napoli 80125 Italy Email: alessandro.amirante@unina.it Tobia Castaldi University of Napoli Via Claudio 21 Napoli 80125 Italy Email: tobia.castaldi@unina.it Amirante, et al. Expires September 5, 2009 [Page 104] Internet-Draft CFW Call Flow Examples March 2009 Lorenzo Miniero University of Napoli Via Claudio 21 Napoli 80125 Italy Email: lorenzo.miniero@unina.it Simon Pietro Romano University of Napoli Via Claudio 21 Napoli 80125 Italy Email: spromano@unina.it Amirante, et al. Expires September 5, 2009 [Page 105]