This section contains the patterns directly related to the Asynchronous Business Process pattern. Other patterns, such as the Business Object and Business Object Collection patterns, are indirectly related, often through the implementation of particular business activities within a process:
Business Process: The Business Process pattern is the synchronous brother of the Asynchronous Business Process pattern. In most cases, the Asynchronous Business Process pattern subsumes this synchronous version simply to protect the client from variability in the length of time it takes to complete a business process.
Event Monitor: The Asynchronous Business Process pattern leaves a problem for clients ”how to determine the progress of the business process. There is no way to determine when a business process completes, fails, or makes any progress with the initial structure of the Asynchronous Business Process pattern. An Event Monitor pattern is an inefficient, but effective, mechanism to track the progress of a business process.
Observer: Event monitors are inefficient mechanisms for tracking the progress of asynchronous business processes. A client may poll hundreds or thousands of times before the status changes when using an event monitor. An Observer, a classic GoF pattern, gives control back to the server for notifying a client when a change in a business process, or business object, takes place.