The Evolution of RSS | 8
The Evolution of RSS
RSS Feature Summary
Here are some key features of the different versions of RSS:
- 0.90 - RDF-based headlines (namespaces and RDF), link and title limits of 15 items, 100-character links, 500-character limit for title
- 0.91 - DTD-based - Added optional descriptions (500-character limit) and managingEditor, publisher, pubDate, webMaster, copyright
- 0.92 - Based on 0.91 - all sub-element items optional
- language tag is optional
- entity-encoded HTML allowed in item description
- item sub-elements:
- source - give credit to news source
- enclosure - payload
- category - identifies a categorization taxonomy
- channel sub-element
- cloud - allows update notification
- all limits are eliminated
- 0.93 - in progress...
- item sub-elements:
- allows multiple enclosures
- item sub-elements:
- 1.0 - Based on 0.90, using RDF and namespaces
- Adds modules including:
- Dublin Core (creator, subject, publisher, contributor, date, type, format, identifier, source, language, relation, coverage, rights [copyright])
- updatePeriod, updateFrequency, updateBase,
- content module (enclosures), taxonomy module (categories), with more on the way.
Developers can use versions 0.91 and 1.0 safely as 1.0 is based on 0.9, which many RSS tools, applications, and portals are able to read. Using 0.92+ is up to their discretion. What we need now are tools that convert between and work with all the various formats. Developers are working on adding 0.92 support to the XML::RSS module (that already supports 0.9, 0.91, and 1.0).
RSS Usage Survey
Ian Davis, CTO of Calaba Ltd. (and Internet Alchemy) ran a special RSS survey for this article to determine the distribution of RSS versions registered in xmlTree.com. Here are the results:
|RSS 1.0 :||86||3.0%|
RSS 0.91 is the dominant format with over 52% of the feeds using version 0.91 registered at xmlTree.com. (May 3, 2001). Dave Winer of Scripting.com reports that a 24-hour poll of active registered My.UserLand RSS sources revealed 32 RSS 0.9 sources and 218 RSS 0.91 sources. (May 9, 2001)http://internetalchemy.org/rss/survey2.html (Previous survey)
Here are some interesting applications based on RSS:
- A cross-platform (including Linux) and open source client application that can read all current version of RSS (all v.9x's and 1.0). By Morbus Iff.
- An Open Wire Service based on RSS by Rael Dornfest of O'Reilly. This RSS news portal aggregates mainly tech news and combines feeds into MOBs, and categories. News can be filtered by date, category, or regexp or keyword. Useful for keeping up on the latest news in your area.
- MetaDot Portal Software
- Open source My Netscape-like portal in a "box," based on the XML::RSS module.
- mod_index_rss allows you to take directories from Apache servers and publish their contents via RSS.
- mod_mp3 is the streaming server for Apache. You can request information from the server via RSS (for instance you can either ask for the collection of music that the server is sending or you can search on a pattern and get an RSS list of just what was in that pattern).
- Open source template-based (uses HTML::Template) RSS to HTML converter, with optional redirects for click-through tracking. Uses XML::RSS to display RSS news on your site. (We use PullRSS on WebRef's footer.)
- Radio Userland
- Client-side Web application development and runtime environment. Essentially a server on your desktop, this standards-based program has a nice news aggregator built in as a demonstration of the power of this extensive application.
- For Slashdot (this is not installed yet on Slashdot, but it is on Slashcode.com) the new search engine takes requests and will respond via RSS. So you can search for Comments/Users/Stories and have it return the data via RSS. Just about every component of Slash including the problem tracker will spit out RSS if you ask it to (so for instance I can follow new reports on certain bugs based on their bug ID and have Evolution display them for me). Thanks to Brian Aker for this update.
- Weblog 2.0
- Uses RSS 1.0 and the Taxonomy and Dublin Core modules to manage channels in various formats plus a Yahoo-like directory. By Jonathan Eisenzopf. (We use Weblog to manage WebRef's front page.)
Created: May 03, 2001
Revised: May 14, 2001