Java Design Pattern - Business Delegate

Question

I've got some questions regarding Java design patterns. I want to know what the lookup service and the business service in the business delegate pattern are exactly used for. I appreciate as much details and information as possible.

Answer 1

The Business Delegate acts as a client-side business abstraction; it provides an abstraction for, and thus hides, the implementation of the business services.

Using a Business Delegate reduces the coupling between presentation-tier clients and the system's Business services

A Business Delegate uses a component called the Lookup Service. The Lookup Service is responsible for hiding the underlying implementation details of the Business service lookup code.

The Business service is a business-tier component, such as an enterprise bean or a JMS component, that provides the required service to the client. It is used to invoke the business methods on behalf of the client.

Structure:

You can find more details about this pattern in oracle website.

Answer 2

The business delegate pattern tries to decouple the clients from the business services. To achieve this you need:

• business delegate that is the object used by clients to request for services;
• lookup service is a bridge used by business delegate to search for services, it encapsulates the search algorithm according to the request made by the delegate;
• business service is the actual service that is offered to clients, usually an EJB or similar J2EE concepts.

By the way this page explains everything quite clearly..