The methods and events in the RemotePresenceclass can be used to subscribe to presence information from remote presentities.

RemotePresence State Transitions

The RemotePresencestate transitions for the subscription state of a target are shown in the following illustration. The state values are the members of the CollaborationSubscriptionStateenumerated type.

One subscription is maintained for each target whose presence is being tracked. Subscriptions to targets connected to a given server can be batched.

  1. The transition from Idleto Subscribingoccurs when the application calls BeginAddTargets.

  2. The transition from Subscribingto Subscribedoccurs when the subscription to the remote presentity succeeds.

  3. The transition from Subscribingto Terminatingoccurs when the subscription to the remote presentity fails.

  4. The transition from Subscribingto WaitingForRetryoccurs for either of the following reasons:

    • For an Office Communicator 2005 presentity, the server requests UCMA 2.0 Core SDK to try subscribing again at a later time. At the end of this period the Office Communicator 2005 presentity is converted to an enhanced presence user.

    • For a remote presentity that belongs to a cross pool, the server requests UCMA 2.0 Core SDK to try subscribing to the cross-pool server.

  5. The transition from WaitingForRetryto Subscribingoccurs within 10 seconds, when the attempt to subscribe is made again for the reasons given in step 4.

  6. The transition from Subscribedto WaitingForRetryoccurs when the server requests UCMA 2.0 Core SDK to close this subscription and create a new subscription. This action can happen at any time.

  7. The transition from Subscribingto Terminatingoccurs when BeginRemoveTargetor BeginRemoveAllTargetsis called. BeginRemoveTargetdoes not show this state change if the remote presentity belongs to the home batch subscription, although internally the remote presentity’s subscription is cancelled.

  8. The transition from Terminatingto Terminatedoccurs whether or not the subscription is successfully ended.

RemotePresence Constructors

The RemotePresenceclass has no public constructors.

RemotePresence Properties

There are no public properties on the RemotePresenceclass.

RemotePresence Methods

The following are the public methods on the RemotePresenceclass.

Copy Code 
// Adds the target in the subscription dispatcher and starts the
subscription for the given target.
public IAsyncResult BeginAddTargets(ICollection<
RemotePresentitySubscriptionTarget> targetsToAdd, AsyncCallback
userCallback, object state);

// Completes the asynchronous operation started by BeginAddTarget.
public void EndAddTargets(IAsyncResult result);

// Begins an asynchronous operation to unsubscribe to a target.
public IAsyncResult BeginRemoveTarget(string uri, AsyncCallback
userCallback, object state);

// Completes the asynchronous operation started by
BeginRemoveTarget.
public void EndRemoveTarget(IAsyncResult result);

// Invokes the refresh operation on all active subscriptions,
client should expect to receive notifications for targets 
// in this batch, for which subscriptions are active.
public IAsyncResult BeginRefresh(AsyncCallback userCallback, object
state);

// Completes the asynchronous operation started by BeginRefresh.
public void EndRefresh(IAsyncResult result);

// Invokes Terminate on all existing subscriptions that are not
already terminating.
public IAsyncResult BeginRemoveAllTargets(AsyncCallback
userCallback, object state);

// Completes the asynchronous operation started by
BeginRemoveAllTargets.
public void EndRemoveAllTargets(IAsyncResult result)

// Returns the current subscription state for a given target.
public CollaborationSubscriptionState
GetCurrentSubscriptionState(string uri)

// Begins a presence query request for a given list of targets for
the given set of presence categories.
// A presence query internally can involve multiple query requests
to different single and pool targets.
// If the user specified a query result handler, then results will
be notified on the given event handler 
// as soon as they are available.
// Calling EndPresenceQuery will return all results for the query.
public IAsyncResult BeginPresenceQuery(
	IEnumerable<string> targets,
	string[] categories,
	EventHandler<RemotePresenceNotificationEventArgs>
queryResultHandler,
	AsyncCallback userCallback,
	object state);

// Ends the asynchronous operation initiated by BeginPresenceQuery.
public IEnumerable<RemotePresentityNotificationData>
EndPresenceQuery(IAsyncResult result);

RemotePresence Events

The following are the public methods on the RemotePresenceclass.

Copy Code 
// Raised when the presence state changes for any target on the
subscription.
public event
EventHandler<RemotePresenceNotificationEventArgs>
PresenceNotificationReceived;

// Raised when the subscription state changes for any target.
public event
EventHandler<RemotePresenceSubscriptionStateChangedEventArgs>
PresenceSubscriptionStateChanged;