With the channels feature in Internet Explorer, you can specify which content is downloaded, and when. You can provide the latest news reports and company information. If your users are upgrading from Internet Explorer 4 or running Windows 98, they can display channels in a channel bar on their desktop.
A channel is a Web site that has been enabled for information-receiving programs. The mechanism that makes this possible is the Channel Definition Format (.cdf) file. You can use the content you already have, such as Web pages and graphics, for channels. You may want to structure it differently so you can make sure users receive the right amount of content in an organized way.
If you are creating channels for multiple operating systems, you should make sure your content works correctly and is readable on all platforms.
A software distribution channel is a mechanism for updating program files (in the form of Java™ class libraries, Java stand-alone applications, ActiveX™ Controls, or platform-native code) to the user's computer. A software distribution channel is based on a .cdf file and the Open Software Distribution (OSD) format.
The .cdf and OSD formats are based on XML (eXtensible Markup Language), a standard for storing and transmitting structured data. Like HTML, an XML-based document contains text annotated with tags. For more information and samples, see the Microsoft Site Builder Network Workshop.
The .cdf file provides an index of resources available in the channel and a recommended schedule for when the channel should be updated on the local computer. A .cdf file contains some tags that specify logos, the files to be updated, and the schedule for updating them.
If the .cdf file includes the ABSTRACT element for each item in a channel, users can view a description of those items. Abstract descriptions are displayed in a ToolTip when the user rests the cursor over the item. Web publishers can use this feature to describe the content of a particular Web page or to attract users' attention and encourage them to review that content immediately.
Note
Open Software Distribution (OSD) provides automatic download of only the software that the user needs, and the correct version of the software. By querying users' computers about existing software and hardware, OSD can make more intelligent decisions about what users need. With new versions of software always coming out, major revisions, minor revisions, and build numbers can bewilder even hard-core users.
OSD simplifies the computing experience further by installing missing components as needed. This means that if the user is missing a component that prevents another program from functioning, OSD can detect this and automatically retrieve the missing component for you. Users get only the components they need. Many of the tags and functions performed with OSD can also be used in .cdf files.