XCON Working Group C. Boulton Internet-Draft Avaya Intended status: Standards Track M. Barnes Expires: May 3, 2009 Nortel October 30, 2008 Instant Messaging Sessions within a Centralized Conferencing (XCON) System draft-boulton-xcon-session-chat-02 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 May 3, 2009. Abstract The document "A Framework for Centralized Conferencing" defines a centralized conference as both signaling and protocol agnostic. The primary examples within this framework focus on audio and video as the media types for the session. This document provides an overview of the mechanisms defined in the centralized conferencing framework that can be used to support Instant Messaging (IM) chat sessions. In addition, the document describes additional functionality and requirements necessary to provide feature rich chat functionality. Boulton & Barnes Expires May 3, 2009 [Page 1] Internet-Draft XCON Chat October 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Protocol Operations . . . . . . . . . . . . . . . . . . . 5 3.2. IM and Conferencing Identifiers . . . . . . . . . . . . 5 4. Basic Operations . . . . . . . . . . . . . . . . . . . . . . . 8 5. Advanced Operations . . . . . . . . . . . . . . . . . . . . . 8 6. Additional Operations . . . . . . . . . . . . . . . . . . . . 8 6.1. Nicknames . . . . . . . . . . . . . . . . . . . . . . . . 8 6.2. Logging . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.3. History . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.4. Indicating Alternate Venue . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . . 10 10.2. Informative References . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . . . 13 Boulton & Barnes Expires May 3, 2009 [Page 2] Internet-Draft XCON Chat October 2008 1. Introduction A Centralized Conference as defined by the "A Framework for Centralized Conferencing" [RFC5239] is both signaling and protocol agnostic. The primary examples within the framework focus on audio and video as the media types for the session. This document provides an overview of the mechanisms and associated framework elements involved when instant messages are the media for the conference. This functionality is often referred to as a "chat room" or simply "chat" as it provides the text equivalent of a voice conversation involving multiple parties. Several existing protocols support this chat functionality, such as Internet Relay Chat (IRC) [RFC2810] and Extensible Messaging and Presence Protocol (XMPP) [RFC3920]. In addition, [I-D.ietf-simple-chat] provides IM chat functionality for a purely SIP signaling based solution option using Message Session Relay Protocol (MSRP) [RFC4975]. The focus of this document is to describe the interface and provide guidelines for the the support of existing IM chat functionality on a conferencing system based on the XCON framework, independent of the specific IM media type used by the client. The details of the use of the XCON framework for chat are provided in the Conference Control Manipulation Protocol (CCMP) call flow document [I-D.barnes-xcon-examples] The functionality described in this document is not intended to replace any of the existing chat protocols, nor is it specifying a new IM protocol. The motivation for this document is to allow clients that use the conferencing framework model for other media types (e.g. voice/video) to utilize the same conference control mechanisms and conferencing system to establish, update and delete a conference instance associated with an IM chat session, independent of the IM chat protocol. In some cases(e.g., MSRP chat), this would provide additional capabilities, such as sidebars. While this approach also allows the conferencing system to provide a natural interworking point for various IM protocols, the details of the interworking are outside the scope of this document. 2. Conventions and Terminology This document reuses the terminology defined in "A Framework for Centralized Conferencing" and the protocol operations defined in the Centralized Conferencing Protocol document [I-D.ietf-xcon-ccmp]. Boulton & Barnes Expires May 3, 2009 [Page 3] Internet-Draft XCON Chat October 2008 3. Overview Figure 1 provides a general illustration of IM clients having a direct, 1:1 connection to the conferencing system. The conferencing system receives IMs sent from a client participating in a conference instance and then distributes them to the other IM sessions associated with the conference instance. +--------+ | IM | | Client | | | +--------+ | | | | | | v +------------+ +--------+ | | +--------+ | IM | | | | IM | | Client |-------------->|Conferencing|<--------------| Client | | | | System | | | +--------+ | | +--------+ +------------+ ^ | | | | | | +--------+ | IM | | Client | | | +--------+ Figure 1: Client Connection The approach in this document is to have no impact on the existing IM Boulton & Barnes Expires May 3, 2009 [Page 4] Internet-Draft XCON Chat October 2008 protocols, while taking full advantage of the functionality provided by the centralized conferencing framework. A basic solution for MSRP based IM chat sessions is documented in [I-D.ietf-simple-chat]. It uses the concept of an "MSRP switch" as the centralized component, whose role is very similar to the MSRP Conferencing Server in this document. The solution in [I-D.ietf-simple-chat] doesn't explicitly take advantage of the centralized conferencing framework model, as it primarily intends to make use of the basic SIP conferencing framework to provide the basic chat functionality. However, that solution approach is compatible with the solution components described in this document, with no impact on that basic solution proposal. One of the advantages of applying the two solutions in concert would be a reuse of the centralized conferencing framework model for advanced features, such as sidebars and private conferences, and manipulation of the conference data. 3.1. Protocol Operations An IM client wishing to join a conference uses standardized centralized conferencing mechanisms for creating and joining a conference, as identified in the centralized conferencing framework and related protocol documents. The request to send an IM to an IM media session is specific to the IM protocol (e.g., MSRP SEND). On issuing a request to send an IM to an IM media session that is a member of a conference instance, the IM will be replicated and forwarded, in the relevant context, to all other IM media sessions that are participants of the conference instance. An IM client wishing to delete a chat room uses standardized mechanisms for deleting a conference instance. Non-signaling specific mechanisms are defined in the Centralized Conferencing Framework [RFC5239] and related protocol document [I-D.ietf-xcon-ccmp]. Protocol specific mechanisms are defined in other documents such as for SIP in the SIPPING Conference Framework [RFC4353]. 3.2. IM and Conferencing Identifiers As highlighted in the overview section, an IM client connecting to a conferencing system has a 1:1 relationship with the IM signaling entity, each having a unique protocol specific session ID. When referring to IM session ID's the document is making reference to the locally (at conferencing system) generated session ID used for IM session signaling identification. In the case of MSRP, this session Boulton & Barnes Expires May 3, 2009 [Page 5] Internet-Draft XCON Chat October 2008 ID is inserted into the local path SDP attribute. An important concept in this proposal is the creation and management of IM sessions. It is important that each IM session created, as identified by a unique IM session ID, is explicitly tied to an associated conference, represented by the conference identifier (as defined in the Centralized Conferencing Framework [RFC5239]). This provides the relevant association between IM session and a centralized conference. A generic example representation is illustrated by the rows contained in Figure 2. +-----------------------------------------+ | Conference Identifier | +-----------------------------------------+ | IM Session ID=8asjdhk | | IM Session ID=38iuhds | | IM Session ID=djiowid | | IM Session ID=389hewu | +-----------------------------------------+ Figure 2: Simple Session Association The Centralized Conferencing Framework[RFC5239] introduces the concept of a conference user identifier defined in [I-D.ietf-xcon-common-data-model]. When a user joins a conference instance through the signaling protocol, it is allocated an appropriate conference user identifer either through authentication or system allocation. The conference user identifer MUST be used in conjunction with an IM session identifier to internally represent a participant in a conference instance. Figure 2 is then expanded to look like Figure 3. Again a row in the table representing a single entry. +--------------------------------------------------------------+ | Conference Identifier | +--------------------------------+-----------------------------+ | IM Session ID=8asjdhk | Conf User ID=839ULjj | | IM Session ID=38iuhds | Conf User ID=0283hHu | | IM Session ID=djiowid | Conf User ID=ncH37H | | IM Session ID=389hewu | Conf User ID=pakdjjH | +--------------------------------+-----------------------------+ Boulton & Barnes Expires May 3, 2009 [Page 6] Internet-Draft XCON Chat October 2008 Figure 3: Advanced Session Association A more complex session association is necessary due to potential for a user to have multiple IM sessions in a single conference instance, such as multi-lingual conference support. In an example with SIP and MSRP, the conference representation in Figure 3 allows for such functionality when separate SIP dialogs represent MSRP sessions. This process becomes complex when multiple SDP MSRP media sessions (m=) are defined in a single payload. This internal representation now needs expanding to enable a conferencing system to explicitly associate a media session (m=). This involves including the media label, as defined in [RFC4574], to maintain the internal conference association. An example is illustrated in Figure 4. +-----------------------------------------------------------------+ | Conference Identifier | +-----------------------------------------------------------------+ | MSRP Session ID=8asjdhk | Conf User ID=839ULjj | Label=iede3 | | MSRP Session ID=38iuhds | Conf User ID=0283hHu | Label=8heus | | MSRP Session ID=838unaH | Conf User ID=0283hHu | Label=3cnu7 | | MSRP Session ID=djiowid | Conf User ID=ncH37Hs | Label=jd38J | | MSRP Session ID=389hewu | Conf User ID=pakdj7H | Label=U83hd | | MSRP Session ID=Ko03jdk | Conf User ID=pakdj7H | Label=ehy3h | +-----------------------------------------------------------------+ Figure 4: Advanced Session Association + Media Label In Figure 4, conference user identifiers '0283hHu' and 'pakdj7H' appear twice. The combination of multiple conference user identifiers and a unique MSRP session ID enables the conference system to clearly identify a specific MSRP instance. The representation also includes the media label, as defined in [RFC4574],for identification purposes. This added property, which is extracted from the SDP media line, enables clear identification when multi SDP media (m=) lines appear in the same SDP payload. A client MUST include the media label attribute defined in [RFC4574] when including multiple MSRP sessions in the same SDP payload. Even in the simplest conferencing system, where users are allowed to enter anonymously, the internal representation described in this section should be observed. In this case, the conferencing system would still internally create a conference user identifier for participant reference purposes. Boulton & Barnes Expires May 3, 2009 [Page 7] Internet-Draft XCON Chat October 2008 4. Basic Operations The basic operations for creating, joining, and deleting a chat based conference are all supported by the XCON framework using CCMP. The discovery of chat rooms available on a specific conferencing system is inherent in the blueprint capability provided by the conferencing system. The protocol details for these basic operations are provided in [I-D.barnes-xcon-examples]. 5. Advanced Operations Advanced chat features, such as sidebars and private messages can also be suppported within the context of the centralized conferencing framework using CCMP. The protocol details for these advanced features are provided in [I-D.barnes-xcon-examples]. 6. Additional Operations This section discusses additional operations or features required to provide chat room functionality. Most of the operations are not explicitly specified in the centralized conferencing framework. However, some of the features and operations are achievable using data maintained by a conferencing system based on the framework. 6.1. Nicknames Nicknames allow a user to define a text string that uniquely identifies the user within a particular chatroom without necessarily reflecting any protocol specific identity (e.g., SIP URI, Conference User Indentifier, etc.). It is also important to note that the functionality to provide nicknames is not limited to users involved in chatrooms, thus it should be a general feature of the conferencing system. However, the mechanism to allow a user to negotiate a nickname with a conferencing system is additional functionality beyond the centralized conferencing framework, and thus is described in [ref:TBD]. Within a conferencing system, all nicknames should map to a conference user identifier. There may be multiple nicknames associated with a single conference user identifier (e.g., a user that has different nicknames for different chat rooms and/or voice/ video conferences). Boulton & Barnes Expires May 3, 2009 [Page 8] Internet-Draft XCON Chat October 2008 6.2. Logging A common chat feature involves logging the history of a chat room. This provides a record of a chat room that can be used when a user first joins a chat room as discussed in Section 6.3. It can also be used to provide a complete capture of a specific chat room session. The centralized conferencing framework does not fully describe the role of recording or logging of active conferences. However, this functionality can be realized with the manipulation of the appropriate elements in the data model using the general conference control protocol operations. One approach for implementing this function would be to have it be based on specific manipulation of the conference by a user with the appropriate permissions (e.g., CHANGE operation to start and stop recording). Another mechanism for implementing this function would be to have a specific user as part of the conference to perform this function, by defining a specific role such as "observer" and having the media proxied to a logging device. 6.3. History A common chat feature allows users to view the past history of chat rooms. This operation is common when a user first joins a chat room that is underway. A user is often offered the option to review a specific number of past messages. Conferencing systems that maintain the history associated with specific chat rooms through logging, as described in Section 6.2, should provide a mechanism, using the conference identifier, to access the specific information requested by a user based on a specific timestamp. The user request for the information and the rendering of the information is specific to the user's session based messaging protocol and may not be supported by all the messaging protocols. 6.4. Indicating Alternate Venue Another chat room feature provides the details of an alternate chat room venue for previously active chat rooms that have been closed, with a related topic. While not detailed in the centralized conferencing framework, this functionality can be accomplished by creating the new chat room as a child or sibling of the previous chat room and providing the Active chat conference object identifier to any valid users that attempt to join a previous chat room. The information about the new chat room can also be provided at the end of a chat room that is being de-activated at the end of the session. Boulton & Barnes Expires May 3, 2009 [Page 9] Internet-Draft XCON Chat October 2008 7. Security Considerations As discussed in the Centralized Conferencing Framework, there are a wide variety of potential attacks related to conferencing, due to the natural involvement of multiple endpoints and the many, often user- invoked, capabilities provided by the conferencing system. Examples of attacks in the context of MSRP conferencing would include the following: an endpoint attempting to receive the messages for conferences in which it is not authorized to participate, an endpoint attempting to disconnect other users, and theft of service, by an endpoint, in attempting to create conferences it is not allowed to create. Since this document describes the use of existing protocols (e.g. MSRP, Conference Control Protocol, SIP, etc.), it also re-uses the security solutions for those protocols and the associated authorization mechanisms. Since this solution makes use of the Centralized Conferencing framework, it makes use of the policy associated with the conference object to ensure that only authorized entities are able to manipulate the data to access the capabilities. This solution also makes use of the privacy and security of the identity of a user in the conference, as discussed in the Centralized Conferencing Framework. 8. IANA Considerations This document requires no IANA registrations. 9. Acknowledgements The authors appreciate the input and comments from Miguel Garcia- Martin and Dave Morgan. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5239] Barnes, M., Boulton, C., and O. Levin, "A Framework for Centralized Conferencing", RFC 5239, June 2008. [I-D.ietf-xcon-common-data-model] Novo, O., Camarillo, G., Morgan, D., Even, R., and J. Boulton & Barnes Expires May 3, 2009 [Page 10] Internet-Draft XCON Chat October 2008 Urpalainen, "Conference Information Data Model for Centralized Conferencing (XCON)", draft-ietf-xcon-common-data-model-12 (work in progress), October 2008. [I-D.ietf-xcon-ccmp] Barnes, M., Boulton, C., Romano, S., and H. Schulzrinne, "Centralized Conferencing Manipulation Protocol", draft-ietf-xcon-ccmp-00 (work in progress), June 2008. 10.2. Informative References [I-D.roach-xcon-chatroom-analysis] Roach, A., "An Analysis of Feature Parity Between XCON/ SIMPLE-Based Chatrooms and Other Chatrooms", draft-roach-xcon-chatroom-analysis-00 (work in progress), August 2007. [I-D.barnes-xcon-examples] Barnes, M., Boulton, C., Miniero, L., and S. Romano, "Centralized Conferencing Manipulation Protocol (CCMP) Call Flow Examples", draft-barnes-xcon-examples-00 (work in progress), July 2008. [RFC2810] Kalt, C., "Internet Relay Chat: Architecture", RFC 2810, April 2000. [RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence Protocol (XMPP): Core", RFC 3920, October 2004. [RFC4353] Rosenberg, J., "A Framework for Conferencing with the Session Initiation Protocol (SIP)", RFC 4353, February 2006. [RFC4975] Campbell, B., Mahy, R., and C. Jennings, "The Message Session Relay Protocol (MSRP)", RFC 4975, September 2007. [I-D.ietf-simple-chat] Niemi, A., Garcia-Martin, M., and G. Sandbakken, "Multi- party Instant Message (IM) Sessions Using the Message Session Relay Protocol (MSRP)", draft-ietf-simple-chat-02 (work in progress), February 2008. [RFC4574] Levin, O. and G. Camarillo, "The Session Description Protocol (SDP) Label Attribute", RFC 4574, August 2006. [RFC4579] Johnston, A. and O. Levin, "Session Initiation Protocol (SIP) Call Control - Conferencing for User Agents", Boulton & Barnes Expires May 3, 2009 [Page 11] Internet-Draft XCON Chat October 2008 BCP 119, RFC 4579, August 2006. Authors' Addresses Chris Boulton Avaya Building 3 Wern Fawr Lane St Mellons Cardiff, South Wales CF3 5EA Email: cboulton@avaya.com Mary Barnes Nortel 2201 Lakeside Blvd Richardson, TX Email: mary.barnes@nortel.com Boulton & Barnes Expires May 3, 2009 [Page 12] Internet-Draft XCON Chat October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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