WebSphere brand IBM WebSphere Presence Server, Version 7.0

Watcher information

To facilitate presence authorization, IBM® WebSphere® Presence Server Component supports watcher information.

Support for watcher information in Presence Server

Presence Server supports watcher information as defined by IETF RFC 3857 and RFC 3858.

A watcher is defined as an entity that requests information about a resource, or user. These requests are made by means of subscriptions. The watcher information for any given resource is a list of all the subscriptions' status to that resource.

Watcher information consists of the current state for all subscriptions to a particular resource. Monitoring watcher information helps you control access to a resource because it provides the raw data you need to create and deploy presence authorization rules.

Examples of subscription states include active, waiting, pending, and terminated. Subscription state is dynamic, changing as users request new subscriptions, as old subscriptions expire, and as subscriptions are approved or rejected by the resource's owners. As a result, it often useful to subscribe to the watcher information for a particular resource.

Watcher information exists in an XML document that contains lists of watchers for a resource/event package pair. For every watcher in the list, the following attributes are included:
  • The watcher's URI
  • The watcher's display name (Optional)
  • A unique identifier (ID) for the watcher
  • Subscription status, for example active or pending
  • The event that caused the transition to the current status
  • Elapsed time since the SUBSCRIBE request that initiated the current subscription (Optional)

Interaction with other Presence Server features

The combination of watcher information and presence authorization rules enables the use of reactive authorization, where authorization occurs through direct user intervention. A user can subscribe to the watcher information for his or her presentity and thus find out when a new watcher is added who is not covered by the existing authorization rules. The user may then add a new authorization rule for the new watcher.

Presence Server also has configuration options to control what information is available to watchers, including white and black lists. Refer to the Configuring section of this information center for more information.




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