The Session Description Protocol (SDP) WebSocket Connection URI Attribute
RFC 8124

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Internet Engineering Task Force (IETF)                   R. Ravindranath
Request for Comments: 8124                                  G. Salgueiro
Category: Standards Track                                          Cisco
ISSN: 2070-1721                                               March 2017

                 The Session Description Protocol (SDP)
                   WebSocket Connection URI Attribute

Abstract

   The WebSocket protocol enables bidirectional real-time communication
   between clients and servers in web-based applications.  This document
   specifies extensions to Session Description Protocol (SDP) for
   application protocols using WebSocket as a transport.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc8124.

Copyright Notice

   Copyright (c) 2017 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Ravindranath & Salgueiro     Standards Track                    [Page 1]
RFC 8124                 WebSocket SDP Attribute              March 2017

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................3
   3. SDP Considerations ..............................................3
      3.1. General ....................................................3
      3.2. "websocket-uri" SDP Attribute ..............................4
      3.3. "websocket-uri" Multiplexing Considerations ................4
   4. SDP Offer/Answer Procedures .....................................5
      4.1. General ....................................................5
      4.2. Generating the Initial Offer ...............................5
      4.3. Generating the Answer ......................................6
      4.4. Offerer Processing of the Answer ...........................7
      4.5. Modifying the Session ......................................7
      4.6. Offerless INVITE Scenarios .................................8
   5. Procedures at WebSocket Client ..................................8
   6. Security Considerations .........................................9
   7. IANA Considerations .............................................9
      7.1. Registration of the "websocket-uri" SDP Media Attribute ....9
   8. References .....................................................10
      8.1. Normative References ......................................10
      8.2. Informative References ....................................10
   Acknowledgements ..................................................12
   Authors' Addresses ................................................12

1.  Introduction

   The WebSocket protocol [RFC6455] enables bidirectional message
   exchange between clients and servers on top of a persistent TCP
   connection (optionally secured with Transport Layer Security (TLS)
   [RFC5246]).  The initial protocol handshake makes use of Hypertext
   Transfer Protocol (HTTP) [RFC7230] semantics, allowing the WebSocket
   protocol to reuse existing HTTP infrastructure.

   Modern web browsers include a WebSocket client stack compliant with
   the WebSocket API [WS-API] as specified by the W3C.  It is expected
   that other client applications (e.g., those running on personal
   computers, mobile devices, etc.) will also make a WebSocket client
   stack available.  Several specifications have been written that
   define how different applications can use a WebSocket subprotocol as
   a reliable transport mechanism.

Ravindranath & Salgueiro     Standards Track                    [Page 2]
RFC 8124                 WebSocket SDP Attribute              March 2017

   For example, [RFC7118] defines a WebSocket subprotocol as a reliable
   transport mechanism between Session Initiation Protocol
   (SIP)[RFC3261] entities to enable use of SIP in web-oriented
   deployments.  Additionally, [RFC7977] defines a new WebSocket