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When a web tier controller receives the requests from the client, it then passes the event to the EJBtier controller, implemented as a session bean, which matches the event to the proper command (Command Pattern). Ultimately, the command invokes the appropriate action on A Session Facade, Which Executes The Business Logic.
The facade encapsulates and hides the complexityof these business objects from clients. In addition, because their implementation details are kept hidden by a facade, the objects can change without affecting the clients.
