SIPREC M. Yan
Internet-Draft P. Kyzivat
Intended status: Informational Huawei
Expires: August 18, 2014 February 14, 2014

Overview for MSRP Recording based on SIPREC
draft-yan-siprec-msrp-recording-00

Abstract

SIPREC is capable of recording interactive text media that is transmitted via RTP. However that format is not commonly used for message or chat scenarios. There is also a need for recording text media carried via MSRP. One case of note is exchange of text between hearing-impaired users and emergence service bureaus. Also, recording support is needed for MSRP used in chat conferences and multimedia conferences.

This document describes how to achieve MSRP channel recording within the mechanism of SIP Recording (SIPREC).

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on August 18, 2014.

Copyright Notice

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Table of Contents

1. Introduction

SIPREC is capable of recording interactive text media that is transmitted via RTP, as defined by [RFC4103]. However that format is not commonly used for message or chat scenarios. There is also a need for recording text media carried via MSRP. One case of note is exchange of text between hearing-impaired users and emergence service bureaus. Also, recording support is needed for MSRP used in chat conferences (as defined by [I-D.ietf-simple-chat]) and multimedia conferences (as defined by [RFC4597]).

Instant message media is carried by a variety of protocols such as IRC, MSRP and XMPP/JINGLE. The SIP based protocol MSRP (as defined by [RFC4975][RFC4976]) supports the delivery of messages and files from one SIPUA to another. When a SIPREC SRC is recording a CS that contains an MSRP channel, it may want to record the messages passing over that channel. To gain access to the messages, the SRC may act as an MSRP client, relay, or switch. The SRC needs to replicate and deliver the messages over an MSRP channel within a Recording Session (RS) to an SRS. The replicated content could be in Message/CPIM format containing plain text, HTML, images, etc. In this document, file delivering sessions have not yet been considered. Other instant message protocols, like IRC or XMPP, are out of scope.

This document describes how MRSP sessions are established between an SRC and SRS, and used for conveying the replicated MSRP Media, and also specifies metadata that describes the recorded MSRP sessions. A Recording Session employing MSRP is established using the normal procedures for establishing INVITE initiated dialogs [RFC3261] and uses SDP for describing the media to be used during the session [RFC4566] as described by [I-D.ietf-siprec-architecture].

2. Definitions

(TBD...)

3. MSRP Recording Architecture

For consistency with [RFC6341] and [I-D.ietf-siprec-architecture], MSRP recording needs to deliver duplicated MSRP message content from the SRC to the SRS, with suitable descriptive metadata. The SRC may be associated with SIP UA (endpoint) with an MSRP client, or with a SIP B2BUA that accesses the media via an MRSP Relay. An SRC may also be associated with a SIP conference focus and an MSRP switch.

3.1. MSRP Client acts as SRC

[RFC4975][RFC4976] describes how an MSRP client communicates to another MSRP client via a SIP session. A MSRP client that has access to the MSRP content to be recorded may act as SRC. The MSRP client may send the replicated media to the SRS along with corresponding metadata.

If the MSRP client/SRC is aware the MSRP session needs to be recorded, it can initiate the establishment of a SIP RS by sending an INVITE to SRS, or vice-versa. The MSRP client/SRC is responsible for notifying the other MSRP client involved in the CS that the MSRP session is being recorded. The MSRP client/SRC is responsible for complying with request from recording aware UAs or through some configured policies indicating that the CS should not be recorded.

    +-------------+
    | MSRP CLIENT |
    +-------------+
      ^
      | (Communication Session)    
      |      
      |  SIP
      v              
    +-------------+   (Recording Session)  +-------------+
    | MSRP CLIENT |<---------------------->|   Recorder  |
    |    (SRC)    |      SIP/Metadata      |    (SRS)    |
    +-------------+                        +-------------+
  
					
					

Figure 1: MSRP Client Acts as SRC

3.2. MSRP Relay acts as SRC

(TBD... RFC4976)

    +-------------+
    | MSRP CLIENT |
    +-------------+
      ^
      | (Communication Session)    
      |  SIP     
    +-------------+   (Recording Session)  +-------------+
    | MSRP RELAY  |<---------------------->|   Recorder  |
    |    (SRC)    |      SIP/Metadata      |    (SRS)    |
    +-------------+                        +-------------+
      | 
      |
      v
    +-------------+
    | MSRP CLIENT |
    +-------------+ 
					
					

Figure 2: MSRP Relay Acts as SRC

3.3. MSRP Switch acts as SRC

(TBD... ietf-simple-chat)

    +-------------+    +-------------+
    | MSRP CLIENT |    | MSRP CLIENT |
    +-------------+    +-------------+   
           ^            ^
            \ SIP      / (Communication Session)
             \        /  SIP  
           +-------------+                     +-------------+
           | MSRP switch | (Recording Session) |   Recorder  |
           |    (SRC)    |<------------------->|    (SRS)    |
           +-------------+    SIP/Metadata     +-------------+
             /        \    
            / SIP      \ SIP    
           v            v
    +-------------+    +-------------+
    | MSRP CLIENT |    | MSRP CLIENT |
    +-------------+    +-------------+
					
					

Figure 3: MSRP Switch Acts as SRC

4. MSRP Recording Protocol

There are several possible ways of passing CS MSRP messages from the SRC to the SRS. Here are three:

  1. For each CS MSRP channel that is recorded, a corresponding new MSRP channel is created in the RS.
  2. For each CS MSRP channel that is recorded, a corresponding MSRP channel is dedicated in the RS. When recording of the CS MSRP channel ceases, the corresponding MSRP channel may be reassigned.
  3. MSRP messages from multiple MSRP participants of a CS are multiplexed (mixed) over a single MSRP channel in the RS.

5. Metadata

(TBD...)

6. Open Issues

  • Is there any need for in-band indication that MSRP is being recorded?
  • MSRP-based file transfers (in scope or not?)

7. IANA Considerations

This document contains no IANA considerations.

8. Security Considerations

Not explicitly covered in this version.

9. References

9.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
[RFC4975] Campbell, B., Mahy, R. and C. Jennings, "The Message Session Relay Protocol (MSRP)", RFC 4975, September 2007.
[RFC4976] Jennings, C., Mahy, R. and A.B. Roach, "Relay Extensions for the Message Sessions Relay Protocol (MSRP)", RFC 4976, September 2007.
[RFC6341] Rehor, K., Portman, L., Hutton, A. and R. Jain, "Use Cases and Requirements for SIP-Based Media Recording (SIPREC)", RFC 6341, August 2011.
[I-D.ietf-siprec-architecture] Hutton, A., Portman, L., Jain, R. and K. Rehor, "An Architecture for Media Recording using the Session Initiation Protocol", Internet-Draft draft-ietf-siprec-architecture-11, December 2013.
[I-D.ietf-simple-chat] Niemi, A., Garcia, M. and G. Sandbakken, "Multi-party Chat Using the Message Session Relay Protocol (MSRP)", Internet-Draft draft-ietf-simple-chat-18, January 2013.

9.2. Informative References

[RFC4103] Hellstrom, G. and P. Jones, "RTP Payload for Text Conversation", RFC 4103, June 2005.
[RFC4566] Handley, M., Jacobson, V. and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006.
[RFC4597] Even, R. and N. Ismail, "Conferencing Scenarios", RFC 4597, August 2006.

Authors' Addresses

Michael Yan Huawei EMail: michael.yan@huawei.com
Paul H. Kyzivat Huawei EMail: pkyzivat@alum.mit.edu