The WebSocket Protocol
RFC 6455
Internet Engineering Task Force (IETF) I. Fette
Request for Comments: 6455 Google, Inc.
Category: Standards Track A. Melnikov
ISSN: 2070-1721 Isode Ltd.
December 2011
The WebSocket Protocol
Abstract
The WebSocket Protocol enables two-way communication between a client
running untrusted code in a controlled environment to a remote host
that has opted-in to communications from that code. The security
model used for this is the origin-based security model commonly used
by web browsers. The protocol consists of an opening handshake
followed by basic message framing, layered over TCP. The goal of
this technology is to provide a mechanism for browser-based
applications that need two-way communication with servers that does
not rely on opening multiple HTTP connections (e.g., using
XMLHttpRequest or <iframe>s and long polling).
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 5741.
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/rfc6455.
Copyright Notice
Copyright (c) 2011 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
Fette & Melnikov Standards Track [Page 1]
RFC 6455 The WebSocket Protocol December 2011
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 5
1.3. Opening Handshake . . . . . . . . . . . . . . . . . . . . 6
1.4. Closing Handshake . . . . . . . . . . . . . . . . . . . . 9
1.5. Design Philosophy . . . . . . . . . . . . . . . . . . . . 9
1.6. Security Model . . . . . . . . . . . . . . . . . . . . . . 10
1.7. Relationship to TCP and HTTP . . . . . . . . . . . . . . . 11
1.8. Establishing a Connection . . . . . . . . . . . . . . . . 11
1.9. Subprotocols Using the WebSocket Protocol . . . . . . . . 12
2. Conformance Requirements . . . . . . . . . . . . . . . . . . . 12
2.1. Terminology and Other Conventions . . . . . . . . . . . . 13
3. WebSocket URIs . . . . . . . . . . . . . . . . . . . . . . . . 14
4. Opening Handshake . . . . . . . . . . . . . . . . . . . . . . 14
4.1. Client Requirements . . . . . . . . . . . . . . . . . . . 14
4.2. Server-Side Requirements . . . . . . . . . . . . . . . . . 20
4.2.1. Reading the Client's Opening Handshake . . . . . . . . 21
4.2.2. Sending the Server's Opening Handshake . . . . . . . . 22
4.3. Collected ABNF for New Header Fields Used in Handshake . . 25
4.4. Supporting Multiple Versions of WebSocket Protocol . . . . 26
5. Data Framing . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.2. Base Framing Protocol . . . . . . . . . . . . . . . . . . 28
5.3. Client-to-Server Masking . . . . . . . . . . . . . . . . . 32
5.4. Fragmentation . . . . . . . . . . . . . . . . . . . . . . 33
5.5. Control Frames . . . . . . . . . . . . . . . . . . . . . . 36
5.5.1. Close . . . . . . . . . . . . . . . . . . . . . . . . 36
5.5.2. Ping . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.5.3. Pong . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.6. Data Frames . . . . . . . . . . . . . . . . . . . . . . . 38
5.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.8. Extensibility . . . . . . . . . . . . . . . . . . . . . . 39
6. Sending and Receiving Data . . . . . . . . . . . . . . . . . . 39
6.1. Sending Data . . . . . . . . . . . . . . . . . . . . . . . 39
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