3 Protocol Details

This protocol operates between two update servers acting in the following roles:

  • DSS: This update server initiates all communication with the USS.

  • USS: This update server responds to requests received from the DSS.

The protocol incorporates support for the following capabilities:

  • Discovering and synchronizing software and driver updates metadata.

  • Downloading content for the updates synchronized by the DSS from the USS.

  • Discovering and synchronizing target groups when the DSS is configured as a replica of the USS.

  • Discovering and synchronizing deployments of the updates to target groups when the DSS is configured as a replica of the USS.

  • Reporting the status of updates on client computers by the DSS to the USS.

The protocol is intended to be stateless wherever possible. However, due to the requirements of authorization and the interrelationships between deployments, updates, and target groups, the DSS MUST execute the steps of this protocol in a specific order. A high-level sequence figure, as specified in section 3.2.4, summarizes the working of the protocol. Further details are provided in the following sections. This section first specifies details that are common between both roles. It then provides additional USS-specific and DSS-specific behavior, respectively.

Information about updates, target groups, and deployments is maintained on each USS, and each DSS obtains this information through a series of SOAP message exchanges that comprise the USS Web Services.

Similarly, information on descendant DSSs, client computers, and the status of updates on those client computers is maintained on each DSS, and the DSS sends this information to its USS through a series of SOAP message exchanges with USS.

A USS can also be configured to store the content associated with updates. In such a configuration, each DSS obtains content from its USS through a series of HTTP operations that comprise the USS Content Download.

If the content is not available from the USS, the DSS obtains content from an Internet website through a series of HTTP operations using the file location URLs obtained from the USS.

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