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