Grey Headline (continued)
Presence
TANDBERG VIDEO COMMUNICATIONS SERVER ADMINISTRATOR GUIDE
Overview |
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Presence is the ability of endpoints to provide information to other users about their current status - such as whether they are offline, online, or in a call. Any entity which provides presence information, or about whom presence information can be requested, is known as a presentity. Presentities publish information about their own presence status, and also subscribe to the information being published by other presentities and FindMe users.
Endpoints that support presence, such as the next release of TANDBERG Movi, can publish their own status information. The VCS can also provide basic presence information on behalf of endpoints that do not support presence, including H.323 endpoints, as long as they have registered with an alias in the form of a URI.
If FindMe is enabled, the VCS can also provide presence information about FindMe users by aggregating the information provided by each presentity configured for that FindMe user.
The Presence application on the VCS supports the
The Presence status pages provide information about the presentities who are providing presence information and the users who are requesting presence information on others.
Presence is supported by clustering. For specific information about how Presence information is managed across Peers in a cluster, refer to the section Clustering and Presence.
The Presence Server application on the VCS is responsible for managing the presence information for all presentities in the SIP domain(s) for which the VCS is authoritative (refer to the Configuring SIP - Domains section for more information). The Presence Server can manage the presence information for locally registered endpoints and presentities whose information has been received via a SIP Proxy (e.g. another VCS Control or Expressway).
The Presence Server is made up of the following services, all of which are enabled (or disabled) simultaneously when the Presence Server is enabled (or disabled):
•Publication Manager - receives PUBLISH messages, which contain the status information about a presentity, and writes this information to the Presence Database. PUBLISH messages are generated by
•Subscription Manager - handles SUBSCRIBE messages, which request information about the status of a presentity. Upon receipt of a SUBSCRIBE message, the Subscription Manager sends a request to the Presentity Manager for information about that presentity, and forwards the information that is returned to the subscriber. The Subscription Manager also receives notifications from the Presentity Manager when a presentity’s status has changed, and send this information to all subscribers.
•Presentity Manager - an interface to the Presence Database. It is used to support VCS features such as FindMe and the PUA, where the presence information provided by a number of different devices must be aggregated in order to provide an overall presence status for one particular presentity.
When the Presentity Manager receives a request from the subscription manager for information on a presentity, it queries the Presence Database for all information available on all the endpoints associated with that particular presentity. The Presentity Manager then aggregates this information to determine the presentity’s current status, and returns this to the Subscription
Manager.
•Presence database - stores current presence information received in the form of PUBLISH messages. Also sends NOTIFY messages to the Presentity Manager to inform it of any changes.
Introduction | Getting Started |
| Overview and |
| System |
| VCS |
| Zones and |
| Call |
| Bandwidth |
| Firewall |
| Applications |
| Maintenance |
| Appendices |
| Status |
| Configuration |
| Configuration |
| Neighbors |
| Processing |
| Control |
| Traversal |
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D14049.04 |
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JULY 2008 |
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