Hi
I have some points concerning SCA Java Component Implementation
Specification that I'd like to clarify.
1/ use of @Service annotation (p. 2)
In this document, it is said that a service offered by a component can be
defined in two ways :
a/ by an interface
Diapositive 4 @Service (HelloService.class)
Public class HelloServiceImpl implements HelloService {
public String hello(String message) {
…
}
HelloService.java (interface) defines the method implemented by the
component in HelloServiceImpl.java
b/ by a class
Diapositive 6 @Service (HelloServiceImpl.class)
Public class HelloServiceImpl implements AnotherInterface {
public String hello(String message) {
…
}
In this case the java class itself defines the service offered by the
component
*my question : Why to have such a choice ? Is an interface not enough to
define service offered by a component ?*
2/ use of @Reference annotation(p.4)
we can use @Reference in one of the following ways :
a/ with setter method
public class MyClientImpl implements MyClient{
private MyService myService;
@Reference
public void setMyService(MyService myService) {
this.myService = myService;
}
b/ with field injection
public class MyClientImpl implements MyClient{
@Reference (name="myService")
protected MyService myService;
...
}
Diapositive 11where myService is the reference to a service used by MyClient
component
*my question : Why and when to prefer setter method than field injection ?*
3/ References (p.4)
Do we have two distinct manners of obtaining references? One through
injection and one through ComponentContextAPI ?
Thanks
Fahim
