J2EE PATTERNS

Presentation Tier:
---------------------
1. Interceptor Pattern : Pluggable filter intercept incoming request and outgoing response

2. Front Controller : Handles requests and manages content retrieval, security, view management,and navigation, delegating to a Dispatcher component to dispatch to a View.

3. View Helper : Generally suggested to view helper for formatting output also use business delegate to access business classes.

4. Composite View : Composite view design pattern is used when multiple subviews are directly embedded to make a single view or layout or template.

5. Dispatch View :  Dispatcher view is a combination of a controller and dispatcher with views and view helpers to handle client requests and prepare  a dynamic presentation as the response.

6. Service to Worker : This is used in larger applications wherein one class is used to process the requests while the other is used to process the view part.


Business Tier :
----------------
1. Business Delegate : Primary target is to reduce coupling between presentation and business tier by provide a proxy to facade.  hiding the underlying implementation  details of the service .

2. Session Facade : Main focus of the facade is to split the total system into sub system by hiding the complexity. It helps to reduce network overhead and improve performance.

3. Transfer/Value Object : Used to exchange data across tiers.it also reduce the network overhead by minimizing the number of calls to get data from another tier.

4. Transfer/Value Object Assembler : Transfer Object Assembler combines multiple Transfer Objects from various business components and services, and returns it to the client.

5. Value List Handler : Value list handler is use to cache the results and allow client to search, traverse and select items from the results.

6. Service Locator  : The service locator design pattern is used when you to implement and encapsulate service and component lookup.

7. Composite Entity : Use Composite Entity to model, represent, and manage a set of interrelated persistent objects rather than representing them as individual

Integration Tier:
------------------
DAO : Encapsulate all access to persistence store.  DAO manages connection with data source to obtain and store data.

Service Activator : Service activator design pattern is use to receive asynchronous requests and invoke one or more business services.