Weaving the Web of News (3/5) - exploring XML

Weaving the Web of News

Open Content Syndication (OCS)

With the proliferation of channel definitions arose the need for a format-transcending listing of syndications. From the InternetAlchemy.org Web site: "The Open Content Directory Format is intended to provide a concise, machine readable-listing of a set of syndicated channels. The directory format is capable of supporting multiple sites, each with multiple channels. Each channel can have muliple formats such as RSS (Rich Site Summary) versions 0.90 or 0.91, Plain Text, Avantgo, WML or Scripting News format format as well as separate publishing schedules or languages."

The format uses RDF for expressing the relationship between items, and Dublin Core (DC), a set of well-defined subjects such as title and creator to describe attributes of channels. Note that this format describes a directory of channels rather than a single channel, so this example is not equivalent to the above, but compliments them:

<?xml version="1.0"?>
<rdf:RDF
  xmlns:rdf = "https://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:ocs = "https://alchemy.openjava.org/ocs/directory#"
  xmlns:dc  = "https://purl.org/metadata/dublin_core#">
  <!-- This is information about this channel listing -->
  <!-- The about attribute points to the directory file,
   usually the same file as the one being parsed -->
  <rdf:description about="https://www.webref.com/xml/column5/ocs.rdf">        
    <!-- This section contains information about the channel directory listing 
-->
    <dc:title>Michael's XML Channel Directory</dc:title>
    <dc:creator>Michael Classen(mailto:[email protected])/dc:creator>
    <dc:description>This is a list of channels about XML</dc:description>
  
    <!-- This is the first channel available -->
    <rdf:description about="https://www.exploringxml.com">        
      <!-- Information about the channel -->
      <dc:title>eXploringXML Channel</dc:title>
      <dc:creator>Michael Classen (mailto:[email protected])/dc:creator>
      <dc:description>This is a channel about eXploringXML at WebReference: 
Free tutorials, examples, and tools for XML</dc:description>
      <dc:subject>Technology, XML, Web, tutorials, examples, 
tools</dc:subject>
      <ocs:image>https://www.webref.com/xml/art/logo.gif</ocs:image>
    
      <!-- This is the first format for this channel -->
      <!-- Information about the RSS version -->
      <rdf:description about="https://www.webref.com/xml/column5/ocs.rss">
        <dc:language>en</dc:language>
        <ocs:format>https://my.netscape.com/rdf/simple/0.9/</ocs:format>
        <ocs:updatePeriod>hourly</ocs:updatePeriod>
        <ocs:updateFrequency>2</ocs:updateFrequency>
        <ocs:updateBase>2000-01-25T00:00</ocs:updateBase>
      </rdf:description>
  
      <!-- This is the second format for this channel -->
      <!-- Information about a plain text version -->
      <rdf:description about="https://alchemy.openjava.org/plain.txt">
        <dc:language>en</dc:language>
        <ocs:contentType>text/plain</ocs:contentType>
        <ocs:updatePeriod>daily</ocs:updatePeriod>
        <ocs:updateFrequency>1</ocs:updateFrequency>
        <ocs:updateBase>2000-01-25T00:00</ocs:updateBase>
      </rdf:description>
    
    </rdf:description>        
  
    <!-- This is the second channel available -->
    <rdf:description about="https://xml.org/channel">        
     ...
    </rdf:description>        
  </rdf:description>        
</rdf:RDF>

Here are some sites that use OCS for their channel directory:

• The Web StartsHere is publishing its entire channel listing in OCS version 0.3 format
• XMLTree is publishing it's entire list of channels in OCS Directory format
• Carmen's Headline Viewer can read in channels from OCS Directory lists
• Network54 publishes over 650 discussion groups in OCS format
• GrokSoup publishes it's channels in OCS.

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Produced by Michael Claßen
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URL: https://www.webreference.com/xml/column5/3.html
Created: Jan. 30, 2000
Revised: Jan. 30, 2000