RFC 2774 (rfc2774) - Page 2 of 20

An HTTP Extension Framework

RFC 2774              An HTTP Extension Framework          February 2000


Abstract

   A wide range of applications have proposed various extensions of the
   HTTP protocol. Current efforts span an enormous range, including
   distributed authoring, collaboration, printing, and remote procedure
   call mechanisms. These HTTP extensions are not coordinated, since
   there has been no standard framework for defining extensions and
   thus, separation of concerns. This document describes a generic
   extension mechanism for HTTP, which is designed to address the
   tension between private agreement and public specification and to
   accommodate extension of applications using HTTP clients, servers,
   and proxies.  The proposal associates each extension with a globally
   unique identifier, and uses HTTP header fields to carry the extension
   identifier and related information between the parties involved in
   the extended communication.

Table of Contents

   1.  Introduction ...............................................3
   2.  Notational Conventions .....................................3
   3.  Extension Declarations .....................................4
    3.1   Header Field Prefixes ...................................5
   4.  Extension Header Fields ....................................6
    4.1   End-to-End Extensions ...................................7
    4.2   Hop-by-Hop Extensions ...................................7
    4.3   Extension Response Header Fields ........................8
   5.  Mandatory HTTP Requests ....................................8
    5.1   Fulfilling a Mandatory Request .........................10
   6.  Mandatory HTTP Responses ..................................11
   7.  510 Not Extended ..........................................11
   8.  Publishing an Extension ...................................11
   9.  Caching Considerations ....................................12
   10. Security Considerations ...................................13
   11. References ................................................13
   12. Acknowledgements ..........................................14
   13. Authors' Addresses ........................................14
   14. Summary of Protocol Interactions ..........................15
   15. Examples ..................................................16
    15.1  User Agent to Origin Server ............................16
    15.2  User Agent to Origin Server via HTTP/1.1 Proxy .........17
    15.3  User Agent to Origin Server via HTTP/1.0 Proxy .........18
   Full Copyright Statement ......................................20









Nielsen, et al.               Experimental