Syndication, which originated in the news industry, is the process of distributing information for republishing purpose.
There are always at least 2 actors involved in the syndication process:
a publisher, who creates the content to be distributed
a consumer, typically a portal, who republishes a possibly customised version of the content created by the publisher.
Often, consumers and publishers will not work directly together but will use the services of a content broker, a “syndicator”, who registers all the contents available from many publishers and redistribute them to the consumer.
The actual syndication process can follow two different models:
full content syndication
The consumer copies locally the publisher full actual content and then replublish it. In this model, a user accessing the consumer site may never know that the information he reads is actually produced by an external party.
headline syndication
The consumer only replicates the headlines of the actual publisher content but not the complete data. If a user wants to access the complete content, the consumer site will redirect him to the main publisher site.
Various protocols and formats have been proposed for syndicating content, some tailored for complete content syndication (like the Vignette backed Information and Content Exchange format [2]), while others are dedicated to headline syndication (RSS, ScriptingNews, etc…)
Since Jetspeed currently only implements a headline syndication system, we’ll only present the OCS and RSS formats that may be used for building such networks.
RSS: Rich Site Summary
The Rich Site Summary (RSS) format [3] is a popular XML based markup for describing web sites headlines. Initially developed by Netscape and Userland in order to incorporate syndicated site headlines in the MyNetscape portal, it has become the preferred headline description format for many public news or weblog sites.
This popularity is due partly because it’s endorsed by a large public Internet portal like Netscape but also because it’s very simple and easy to generate.
For example, here’s the markup describing a single headline element in the RSS channel :
New <a href="/advanced-technologies-present-growth-potential-for-europe-tech.html">contract wins in Europe</a>
http://intranet/press?id=4552
The element indicates a new headline, the element describes the title of the headline while the <link> element references the location were the full information is available.
</p>
<p>A complete RSS channel would be composed of an enumeration of such items, encapsulated in a channel description that may contain some meta data as well a descriptive image.</p>
<br /><rss version="0.91">
<br /> <channel>
<br /> <title>Apache Week The essential resource for anyone running an Apache server, or anyone responsible for running Apache-based services. http://www.apacheweek.com/
Copyright 2000, C2Net Europe Ltd
http://www.apacheweek.com/issues/00-12-15#proapache
We review the book Beginning PHP4 from Wrox Press
Apache Week Holiday giveaway http://www.apacheweek.com/issues/00-12-15#awfree
Four copies of the book "Beginning PHP4" are up for grabs in our December competition
Apache status http://www.apacheweek.com/issues/00-12-15#status
Apache 2.0a9 released
In summary, RSS is a very attractive format for describing sites main features or any easily itemised information. It is easy to create, orthogonal to the main content and, being presentation independent, compatible with many displayed formats.
OCS: Open Content Syndication description format
Where RSS goal is to describe channels of content available from the information publishers, OCS (Open Content Syndication description format) [4] is a markup dedicated to describe a directory of channels, commonly called a “feed”, available for syndication.
This format is used by syndicators to distribute their channels directory to consumers. The following diagram illustrates how OCS and RSS formats interact in the headline syndication process between syndicators, publishers and consumers.
OCS is used for distributing the list of all the registered content sites available from a given syndicator. It provides the necessary meta data information that the portal may use to select appropriate channels for the portal users as well as update frequencies and content format descriptions. Once an OCS feed is retrieved by a consumer, he may access and replicate any channel information he’s interested into directly from the publisher site.
A complete valid OCS file contain a collection of channel descriptions, arranged in a hierarchal organisation as mandated by the specification :
It may be used to distribute any type of channel description formats, not only RSS, and may even asscoiate several descriptions format to a single channel.
The markup structure is a little more complex than RSS as OCS is built upon the RDF (Resource Description Format) W3C standard and the DC (Dublin Core) standard document attributes.
A simple channel description may look like this:
Jetspeed
Jetspeed Project Team
Jetspeed is a multi-device portal system with simple syndication capabilities
This entry describes the channel identified in the “about” attribute of the first element. It gives some meta data on the actual content (title, creator and description) but also lists all the available headline formats for this resource in the nested elements. In this example, there’s only one RSS file available corresponding to this channel.
