Open Software Description OverviewOpen Software Description Overview*
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Open Software Description Overview

Open Software Description (OSD) provides the vocabulary to do software updates through the Internet. Microsoft® Internet Explorer 4.01 provides some enhancements to this support (for more information on these changes, see Changes in Microsoft Internet Explorer 4.01). When new versions of your software become available, OSD provides a mechanism, known as publishing, to notify the user. In addition, OSD provides the functionality to describe in great detail how to install ActiveX™ Controls, and Java packages and class files.

The OSD vocabulary is used in these ways:

Automatically Notifying Users of New Versions
Updating ActiveX Controls Whenever New Versions Are Available
Extending Internet Component Download
Extending the Channel Definition Format (CDF)

Changes in Microsoft Internet Explorer 4.01

The following table briefly summarizes the changes between Microsoft Internet Explorer 4.0 and Microsoft Internet Explorer 4.01.
Feature 4.0 4.01
Advertise new application version yes yes
Precache new application version yes yes
OSD-aware shortcuts no yes
ActiveX control precache yes yes
ActiveX channel upgrade no yes
OSD-based Java install yes yes

Note Internet Explorer 4.0 is able to precache an ActiveX control only if an OBJECT tag uses the same code base as the software update channel.

Automatically Notifying Users of New Versions

OSD can be used to automatically notify the user when a new version is available, if the user is subscribed to the appropriate software distribution channel. This notification occurs when the user launches the application from the shortcut (.lnk). The new version can be precached in the Internet Explorer cache, waiting to be installed offline or online when the user chooses to upgrade.

This feature is available to applications that:

For an example of how to use OSD to automatically notify users of new versions, see Publishing Applications to the Internet Using OSD.

Updating ActiveX Controls Whenever New Versions Are Available

If an ActiveX control is available on the user's computer and the user is subscribed to that control's software update channel, OSD allows the system to automatically update the control with a newer version as soon as the user browses to any Web site that uses that control.

For an example of how to use OSD to automatically update an ActiveX control, see Automatically Updating ActiveX Controls Using Software Update Channels

Extending Internet Component Download

In Microsoft Internet Explorer 3.0, the installation and dependency information for software (usually used for ActiveX Controls) was contained in an INF file. For Microsoft Internet Explorer 4.0, using OSD provides three main advantages:

For more information on adding language dependencies using OSD, see Setting Language Dependency Using OSD. For more information on extending Internet Component Download, see Extending Internet Component Download Using OSD in the Internet Component Download documentation.

Extending the Channel Definition Format (CDF)

CDF provides the vocabulary for describing a channel, or an automatic distribution of Web content. OSD adds the vocabulary necessary for describing software packages. In Microsoft Internet Explorer, recognizing OSD tags in a CDF file allows automatic software updates. An application of this concept is the Microsoft Internet Explorer 4.0 Software Updates channel itself. This channel is a CDF that contains additional OSD tags.

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