Another type, software distribution channels, provides the ability to distribute and update software packages via the Web. Users subscribe to them in the same way, by clicking on a link to the channel's CDF file. Software distribution channels are downloaded and installed in the background without user intervention. In order for this mechanism to work, users must set their browser's security setting to low. Users are notified of software updates by a red starburst that appears over the top left-hand corner of the channel's icon.
Users also have the option of being notified by mail when an update occurs.
When an update is detected, a mail message is sent containing a short description of the update. The software installed by a software distribution channel can be removed by right-clicking on the software package's entry and selecting Remove. Developed through a joint effort by Microsoft and Marimba, the OSD specification has been submitted for review to the World Wide Web Consortium. OSD allows for the creation of custom extensions called namespaces. Last month's column covered most of the tags, elements, and attributes that make up the Channel Definition Format.