J2EE Pattern

Transfer Object Pattern

Creational patterns Structural patterns Behavioral pattern J2EE patterns Abstract Factory Adapter  Chain of Responsibility MVC  Builder Bridge  Command  Business Delegate Factory method Composite  Interpreter  Composite Entity Prototype Decorator  Iterator  Data Access Object Singleton Façade Mediator  Front Controller Flyweight  Memento  Intercepting Filter Proxy  Observer  Service Locator State  Transfer Object Strategy  Template Method Visitor

Transfer Object Pattern

Define transfer Object Pattern

Using a serializable class to act as data carrier, grouping related attributes, forming a composite value and working as a return type from remote business method. Also known as Value object.

Where to use & benefits

Get related values from remote business method. Fetch multiple value in one trip. Decrease network traffic. Minimize latency and server resource usage. Related patterns include Composite view

Example of Transfer Object pattern

In the J2EE server, the client tier may make several calls to retrieve data from the enterprise bean. Even in the same machine, the every call from the client tier to the server tier is a remote method call. Think about use Transfer Object design pattern to retrieve related attributes and return a single object instead of each call just for retrieving a single attribute value. The transfer object is passed by value to the client. All calls to the transfer object instance are local calls to the client, so such design saves a lot of network traffic. Let's say that you have a remote banking system. If the user has five requests one time, you should design your system to give response once, not five times. You may need to group all return values from these five requests to an object carrier and then return to client just once. Once the client program receives the instance of this object, it invokes the accessors and gets value to display. The total network traffic for one user just once.