Guidelines for new URL Schemes
RFC 2718
Document | Type |
RFC - Informational
(November 1999; No errata)
Obsoleted by RFC 4395
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Authors | Larry Masinter , Dan Zigmond , Harald Alvestrand , Richard Petke | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 2718 (Informational) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group L. Masinter Request for Comments: 2718 Xerox Corporation Category: Informational H. Alvestrand Maxware, Pirsenteret D. Zigmond WebTV Networks, Inc. R. Petke UUNET Technologies November 1999 Guidelines for new URL Schemes Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. Abstract A Uniform Resource Locator (URL) is a compact string representation of the location for a resource that is available via the Internet. This document provides guidelines for the definition of new URL schemes. 1. Introduction A Uniform Resource Locator (URL) is a compact string representation of the location for a resource that is available via the Internet. RFC 2396 [1] defines the general syntax and semantics of URIs, and, by inclusion, URLs. URLs are designated by including a "<scheme>:" and then a "<scheme-specific-part>". Many URL schemes are already defined. This document provides guidelines for the definition of new URL schemes, for consideration by those who are defining and registering or evaluating those definitions. The process by which new URL schemes are registered is defined in RFC 2717 [2]. Masinter, et al. Informational [Page 1] RFC 2718 Guidelines for new URL Schemes November 1999 2. Guidelines for new URL schemes Because new URL schemes potentially complicate client software, new schemes must have demonstrable utility and operability, as well as compatibility with existing URL schemes. This section elaborates these criteria. 2.1 Syntactic compatibility New URL schemes should follow the same syntactic conventions of existing schemes when appropriate. If a URI scheme that has embedded links in content accessed by that scheme does not share syntax with a different scheme, the same content cannot be served up under different schemes without rewriting the content. This can already be a problem, and with future digital signature schemes, rewriting may not even be possible. Deployment of other schemes in the future could therefore become extremely difficult. 2.1.1 Motivations for syntactic compatibility Why should new URL schemes share as much of the generic URI syntax (that makes sense to share) as possible? Consider the following: o If fragment syntax isn't shared between two schemes, (e.g. "<a href="#foo">"), you can't move individual completely self referential documents between schemes without rewriting the embedded references within the document. In the Web, the fragment syntax is a property of the media type, and evaluated by the client. o If fragment syntax is not shared between different media types of the same capability (e.g. HTML, XML, Word, or image types such as GIF, JPEG, PNG) then you can't have a URI reference that can evolve to superior media types as they become available, or even likely work properly today with content negotiation. o If relative syntax (to the extent of understanding the URI is relative, and what part of the URI string is relative) isn't shared between two schemes, (e.g. "<a href="foo">"), you can't move sets of documents that are internally self referential between schemes without rewriting the embedded URIs. o If the ".." syntax as a path component in relative URI's isn't shared between schemes, you can't easily have sets of document sets and refer to them between schemes without rewriting the embedded references. Masinter, et al. Informational [Page 2] RFC 2718 Guidelines for new URL Schemes November 1999 o If the "/" syntax (to the extent of understanding that the URI refers to a path relative to the current naming authority, see section 2.1.1) isn't shared, you can't have multiple sets of documents easily be moved up or down in a relative hierarchy of names and share a common set of documents between them, without rewriting the content, shared either in that scheme or between schemes. The best example is a site that has a common set of GIF's, JPEG and PNG images, and you want to reorganize the site changing the depth of a subtree from one depth to another, or fromShow full document text