HYBI S. Loreto
Internet-Draft Ericsson
Intended status: Standards Track February 23, 2010
Expires: August 27, 2010
HyBi Requirements and Features
draft-loreto-hybi-requirements-00
Abstract
This document considers the requirements and resulting features
needed for the design of the WebSocket Protocol. The goal of the
document is to provide a stable base for protocol design and related
discussion.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. HyBi Terminology . . . . . . . . . . . . . . . . . . . . . 3
3. WebSocket Requirements . . . . . . . . . . . . . . . . . . . . 4
3.1. WebSocket Client Requirements . . . . . . . . . . . . . . . 4
3.2. WebSocket Server Requirements . . . . . . . . . . . . . . . 5
3.3. WebSocket Proxies Requirements . . . . . . . . . . . . . . 5
3.4. WebSocket Security Requirements . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
HTTP [RFC2616] is a client/server protocol, where the HTTP servers
store the data and provide it when it is requested by clients. When
used to used to retrieve data from an HTTP server, the client sends
HTTP requests to the server, and the server returns the requested
data in HTTP responses. So the client has to poll continuously the
server in order to receive new data.
Recently techniques that enable bidirectional communication over HTTP
have become more pervasive. Those techniques reduce the need to poll
continuously the server thanks to the usage of HTTP hanging requests
and multiple connections between the client and the server
[I-D.loreto-http-bidirectional].
The goal of HyBi is to provide an efficient and clean two-way
communication channel between client and server.
The communication channel will:
o allow each side to, independently from the other, send data when
is willing and ready to do it;
o rely on a single TCP connection for traffic in both the
directions.
o reduce the high overhead produced by HTTP headers in each request/
response.
In the following sections we list and analyse the requirements from
the perspective of clients and servers.
2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
described in BCP 14, RFC 2119 [RFC2119] and indicate requirement
levels for compliant implementations.
2.1. HyBi Terminology
This document uses the following HyBi-related terms:
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connection: A transport layer virtual circuit established between a
client and a server for the purpose of communication.
frame: The basic unit of Web Socket communication, consisting of a
structured sequence of octets matching the syntax defined in the
actual protocol and transmitted on the established communication
channel.
origin server: The server on which a given resource resides or is to
be created.
3. WebSocket Requirements
REQ. 1: The Web Socket Protocol MUST run directly on top of TCP
transport protocol.
REQ. 2: The Web Socket Protocol MUST layer a minimal framing
mechanism on top of TCP data stream.
REQ. 3: The Web Socket Protocol MUST define the supported frame
types.
REQ. 4: Textual data MUST be encoded as UTF-8.
REQ. 5: The protocol MUST be designed to support different frame
types (e.g. binary).
REQ. 6: The Web Socket Protocol MUST be designed in such a way that
its servers can share a port with HTTP servers, as by default the
Web Socket Protocol uses port 80 for regular Web Socket
connections and port 443 for Web Socket connection tunnelled over
TLS.
3.1. WebSocket Client Requirements
REQ. 7: The Web Socket Client MUST be able to set up a communication
channel sending to a Web Socket Server a well defined handshake.
REQ. 8: The Web Socket Client MUST be able to request the server,
during the handshake, to use a specific Web Socket sub-protocol.
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REQ. 9: The Web Socket Client MUST have the ability to send
arbitrary text content to the server on the established
communication channel, in the form of ordered discrete blocks.
REQ. 10: The Web Socket Client MUST have the ability to send
arbitrary binary content to the server on the established
communication channel, in the form of ordered discrete blocks.
3.2. WebSocket Server Requirements
REQ. 11: The Web Socket Server that accept to set up, with a Web
Socket Client, a communication channel MUST send back to the Web
Socket Client a well defined handshake.
REQ. 12: The Web Socket Server MUST have the ability to send
arbitrary text content to the client on the established
communication channel, in the form of ordered discrete blocks.
REQ. 13: The Web Socket Server MUST have the ability to send
arbitrary binary content to the client on the established
communication channel, in the form of ordered discrete blocks.
3.3. WebSocket Proxies Requirements
Todo
3.4. WebSocket Security Requirements
REQ. 14: The Web Socket Protocol MUST use the Origin-based security
model commonly used by Web browsers to restrict which Web pages
can contact a Web Socket sever when the Web Socket protocol is
used from a Web page.
REQ. 15: When used directly (not from a Web page), the WebSocket
Protocol MUST use an equivalent security model.
4. Security Considerations
5. IANA Considerations
This requirements document does not mandate any immediate IANA
actions. However, such IANA considerations may arise from future
HyBi specification documents which try to meet the requirements given
here.
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6. Acknowledgments
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[I-D.loreto-http-bidirectional]
Loreto, S., Saint-Andre, P., Wilkins, G., and S. Salsano,
"Best Practices for the Use of Long Polling and Streaming
in Bidirectional HTTP", draft-loreto-http-bidirectional-01
(work in progress), October 2009.
Author's Address
Salvatore Loreto
Ericsson
Hirsalantie 11
Jorvas 02420
Finland
Email: salvatore.loreto@ericsson.com
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