[news.eclipse.stp] Re: Reusing SCA Service Implementations

[Stephane Drapeau <Stephane.Drapeau@xxxxxxx>]

Hi Michael,

> Michael Gebhart wrote:
> > Hi,
> >
> > when using the SCA editor to create my service architecture, I can
> > easily implement services. I can write a java class and set it as the
> > implementation of a component.
> >
> > My question is: Can I only use this implementation within a SCA runtime?

No. Your implementation doesn't depend on an particular SCA runtime. 
There is only a dependance with the SCA annotations (for instance 
@Remotable is necessary if you want to use a WS binding)

> > We have a typical application server running and don't wanna provide a
> > SCA runtime. But we'd like to use SCA for modeling the architecture.

Yep, I think that the SCA Designer is a great tool for modeling the 
architecture. ;)
But, what a pity that you don't use an SCA runtime... ;)

> > Or do we have to manually adapt the implementation that it works within
> > a typical WS-compliant java application server?

I don't believe it. The service that you wrote for your SCA assembly 
contains only business logic.

> > Is the SCA way an alternative for the usual web service programming? Is
> > it still necessary to write the web services as we have done it before?
> > (Using JAX-WS etc.)

No. You only need to define a web service binding in your SCA assembly 
file. The SCA runtime will generate the wsdl file for the service.

Below a sample:

The interface:
package helloworld;
import org.osoa.sca.annotations.Remotable;
@Remotable
public interface HelloWorld {
    String sayHello(String name);
}

The implementation:
package helloworld;
public class HelloWorldImpl implements HelloWorld {
	public String sayHello(String name) {
		return "Hello " + name;
	}
}

Teh SCA assembly file:
<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"; 
xmlns:c="http://helloworld"; 
xmlns:t="http://tuscany.apache.org/xmlns/sca/1.0"; name="helloworld" 
targetNamespace="http://helloworld";>
  <component name="HelloWorldComponent">
    <implementation.java class="helloworld.HelloWorldImpl"/>
    <service name="HelloWorld">
      <binding.ws uri="http://localhost:8080/HelloWorld"/>
    </service>
  </component>
</composite>

A class to run the SCA assembly with Tuscany:
package helloworld;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import org.apache.tuscany.sca.host.embedded.SCADomain;
public class Client {
	public static void main(String[] args) throws Exception {
		SCADomain scaDomain = SCADomain.newInstance("helloworld.composite");
		HelloWorld hw = scaDomain.getService(HelloWorld.class, "helloworld");

		BufferedReader bufferedReader = new BufferedReader(
				new InputStreamReader(System.in));
		bufferedReader.readLine();
		scaDomain.close();
	}
}

Launch this class. You should have your web service live, and 
http://localhost:8080/HelloWorld?wsdl should give you back a generated 
wsdl for the service.

Stéphane Drapeau
Obeo


PS : Thanks Antoine