Hyper Text Caching Protocol (HTCP/0.0) (RFC2756)
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2019-Feb-10
Internet Society Requests For Comment (RFCs)
P. Vixie: AUTHOR [+1]
This document describes HTCP, a protocol for discovering HTTP caches and cached data, managing sets of HTTP caches, and monitoring cache activity. This is an experimental protocol, one among several proposals to perform these functions. This memo defines an Experimental Protocol for the Internet community.
Network Working Group P. Vixie Request for Comments: 2756 ISC Category: Experimental D. Wessels NLANR January 2000
Hyper Text Caching Protocol (HTCP/0.0)
Status of this Memo
This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document describes HTCP, a protocol for discovering HTTP caches and cached data, managing sets of HTTP caches, and monitoring cache activity. This is an experimental protocol, one among several proposals to perform these functions.
1. Definitions, Rationale and Scope
1.1. HTTP/1.1 (see [RFC2616]) permits the transfer of web objects from "origin servers," possibly via "proxies" (which are allowed under some circumstances to "cache" such objects for subsequent reuse) to "clients" which consume the object in some way, usually by displaying it as part of a "web page." HTTP/1.0 and later permit "headers" to be included in a request and/or a response, thus expanding upon the HTTP/0.9 (and earlier) behaviour of specifying only a URI in the request and offering only a body in the response.
1.2. ICP (see [RFC2186]) permits caches to be queried as to their content, usually by other caches who are hoping to avoid an expensive fetch from a distant origin server. ICP was designed with HTTP/0.9 in mind, such that only the URI (without any headers) is used when describing cached content, and the possibility of multiple compatible bodies for the same URI had not yet been imagined.
Vixie & Wessels Experimental [Page 1]
RFC 2756 Hyper Text Caching Protocol (HTCP/0.0) January 2000
1.3. This document specifies a Hyper Text Caching Protocol (HTCP) which permits full request and response headers to be used in cache management, and expands the domain of cache management to include monitoring a remote cache’s additions and deletions, requesting immediate deletions, and sending hints about web objects such as the third party locations of cacheable objects or the measured uncacheability or unavailability of web objects.
2. HTCP Protocol
2.1. All multi-octet HTCP protocol elements are transmitted in network byte order. All RESERVED fields should be set to binary zero by senders and left unexamined by receivers. Headers must be presented with the CRLF line termination, as in HTTP.
2.2. Any hostnames specified should be compatible between sender and receiver, such that if a private naming scheme (such as HOSTS.TXT or NIS) is in use, names depending on such schemes will only be sent to HTCP neighbors who are known to participate in said schemes. Raw addresses (dotted quad IPv4, or colon-format IPv6) are universal, as are public DNS names. Use of private names or addresses will require special operational care.
2.3. HTCP messages may be sent as UDP datagrams, or over TCP connections. UDP mu...