Lock Processing Example Flow

The following example demonstrates common locking requirements.

Two agents receive messages that require changes to one Customer instance.

Note that event preprocessors are multi-threaded (see Event Preprocessors for more details).

  1. A message comes into a channel on Agent A: a change to a customer address. TIBCO BusinessEvents dequeues the message from the queue, deserializes the message to an event, and calls the event preprocessor function. The preprocessor acquires a lock using the customer’s extID as the key:
    Cluster.DataGrid.Lock(Customer@extId, -1, false);

    This function causes the thread to stop until it gets the lock. In this example, the thread gets the lock.

  2. Only one thread handles the RTC. Other event preprocessor threads go into a queue. During the RTC, a rule executes and modifies the customer address. After RTC completes, the post RTC phase begins: the address change is written to L1 cache, the cluster cache, and the backing store in parallel. Messages arising from the RTC are sent.
  3. After the post RTC actions are completed, the lock is released.
  4. Agent B that contains the same function shown in Step 1 (hence the same locking string) can now acquire the lock that is the function returns true. It proceeds with rule execution and post RTC phase and finally releasing the lock.