Channel Definition Format

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For other uses of "CDF", see CDF (disambiguation).

Channel Definition Format (CDF) is an XML file format used in conjunction with Microsoft's Active Channel, Active Desktop and Smart Offline Favorites technologies. The format is designed to "offer frequently updated collections of information, or channels, from any web server for automatic delivery to compatible receiver programs."[1] Active Channel allows websites to be listed and syndicated with the end-user's desktop. Smart Offline Favorites, like channels, enable users to view webpages from the cache.


Submitted to the World Wide Web Consortium (W3C) in March 1997 for consideration as a web standard,[2] CDF marked Microsoft's attempt to capitalize on the short-lived push technology trend led by PointCast.[3] The most notable implementation of CDF was Microsoft's Active Desktop, an optional feature introduced with the launch of the Internet Explorer 4.0 browser on 30 September 1997.[4][5] While CDF and Active Channel were introduced with the launch of Internet Explorer 4.0, Smart Offline Favorites was introduced with the launch of Internet Explorer 5.0.

CDF served as a model in the emergence of web syndication and prefigures some aspects of the RSS file format introduced by Netscape in 1999.[6] Unlike RSS, CDF was never widely adopted and its use remains very limited. As a direct result, in 2006 Microsoft removed CDF support from Internet Explorer 7.


A generic CDF file:

<?xml version="1.0" encoding="UTF-8"?>
<CHANNEL HREF="http://domain/folder/pageOne.extension"
    <TITLE>Title of Channel</TITLE>
    <ABSTRACT>Synopsis of channel's contents.</ABSTRACT>
      <INTERVALTIME DAY="14"/>
    <LOGO HREF="wideChannelLogo.gif" STYLE="IMAGE-WIDE"/>
    <LOGO HREF="imageChannelLogo.gif" STYLE="IMAGE"/>
    <LOGO HREF="iconChannelLogo.gif" STYLE="ICON"/>
    <ITEM HREF="pageTwo.extension"
        <TITLE>Page Two's Title</TITLE>
        <ABSTRACT>Synopsis of Page Two's contents.</ABSTRACT>
        <LOGO HREF="pageTwoLogo.gif" STYLE="IMAGE"/>
        <LOGO HREF="pageTwoLogo.gif" STYLE="ICON"/>

See also[edit]


  1. ^ Ellerman, Castedo (1997-03-10). "Channel Definition Format Submission 970309". Retrieved 2011-07-08. 
  2. ^ "Microsoft Leads Industry to Standardize on Formats for Internet Push Channels; Submits Channel Definition Format Specification to W3C". Microsoft. 1997-03-12. Retrieved 2014-09-13. 
  3. ^ Kelly, Kevin; Gary Wolf (March 1997). "Push!". Wired 5 (03). Retrieved 2014-09-13. 
  4. ^ Lash, Alex (1997-10-01). "New Explorer finally here". CNET News. Retrieved 2015-12-29. 
  5. ^ Glascock, Stuart (1997-10-06). "IE 4.0 finally ships, to be built into future OS versions". Computer Reseller News (757). p. 315. 
  6. ^ Hammersley, Ben (2005). "A short history of RSS and Atom". Developing Feeds with RSS and Atom. Sebastopol: O’Reilly. pp. 2–11. 

External links[edit]