Re: Implementing a service using request factory : static method in a type vs instance methods in a service class

On Saturday, April 6, 2013 11:53:15 AM UTC+2, Aman Sharma wrote:

I'm using JDO with RequestFactory and MVP pattern. Example to  implement service in firty way is very clear to me from https://developers.google.com/web-toolkit/doc/latest/DevGuideRequestFactory#entity_service

But how do you implement a service as instance methods in a service class? I am not very clear with the definition and use of ServiceLocator , Locator. When do you use them?

Is a service class different from persistence capable entity?

There are 2 ways to have your RequestContext methods backed by instance methods:

• a return-type of InstanceRequest<SomeProxy, Result> tells RF to call the method on the domain object backing the SomeProxy instance passed to using()
  
• a locator in the @Service or @ServiceName annotation tells RF to instantiate the ServiceLocator class and then use it to get an instance of the service class.

The Locator that you use in @ProxyFor / @ProxyForName is about moving the findXxx static method and the getId and getVersion instance methods out of your entity and in a Locator instance.

The doc only shows 2 ways of using RF:

• using the entity as both an entity and service (with static methods): this is the default when you don't provide locators (this is because the Spring Roo guys with whom RF was built tried to somehow mimic Ruby on Rails / ActiveRecord),
  
• removing all static methods from the entity by using both a Locator and ServiceLocator

but you can mix and match things as you like: you can use Locator without ServiceLocator, or ServiceLocator without Locator; when you don't use a ServiceLocator, your service class can be distinct from an entity (domain object).

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