Connecting to http://localhost:7600/petals/ws ...
PEtALS CLI. Tape 'help' for help.

/> h
PEtALS prompt usage:
 - a, addart                Upload an artifact to the petals server
 - c, connect               Connects the client to a petals server
 - e, endpoint              Displays the list of endpoints
 - i, info                  Displays the container information
 - ic, install              Deals with the component installation and uninstallation
 - j, jbiart                Displays the list of JBI artefacts
 - q, stop                  Stops the container
 - r, repo                  Displays the petals repository content
 - t, topology              Displays the petals topology
 - x, shutdown              Shutdown the container

/>

/> t
 Displays the petals topology
==============================
 + Container #1
  - Name       : NODE-EBM-00
  - Address    : node00.ebmwebsourcing.com
 + Container #2
  - Name       : NODE-OVH-00
  - Address    : node00.ovh.net

/> e
 Displays the list of endpoints
================================
 + Endpoint #1
  - Name       : ProductWebServicePort
  - Service    : {http://productws. partner.soa4all.com/}ProductWebServiceService
  - Interfaces : {http://productws. partner.soa4all.com/}ProductWebService,
  - Location (component / container / domain)   : petals-bc-soap / NODE-EBM-00 / subdomain1
 + Endpoint #2
  - Name       : IWebShopPort
  - Service    : {http://mamboofive.partner.soa4all.com/}IWebShopService
  - Interfaces : {http://mamboofive. partner.soa4all.com/}IWebShop,
  - Location (component / container / domain)   : petals-bc-soap / NODE-EBM-00 / subdomain1
 + Endpoint #3
  - Name       : HanivalProductWSPort
  - Service    : {http://hanivalproductws. partner.net/}HanivalProductWSService
  - Interfaces : {http://hanivalproductws. partner.net/}HanivalProductWS,
  - Location (component / container / domain)   : petals-bc-soap / NODE-EBM-00 / subdomain1
 + Endpoint #4
  - Name       : SemanticSpaceAggImplPort
  - Service    : {http://ws.aggregator.space.dsb.soa4all.eu/}SemanticSpaceAggImplService
  - Interfaces : {http://ws.aggregator.space.dsb.soa4all.eu/}SemanticSpaceWS,
  - Location (component / container / domain)   : petals-bc-soap / NODE-OVH-00 / subdomain1
 + Endpoint #5
  - Name       : SemanticSpaceWSImplServiceEndpointOVH
  - Service    : {http://ws.space.dsb.soa4all.eu/}SemanticSpaceWSImplService
  - Interfaces : {http://ws.space.dsb.soa4all.eu/}SemanticSpaceWS,
  - Location (component / container / domain)   : petals-bc-soap / NODE-OVH-00 / subdomain1
 + Endpoint #6
  - Name       : SemanticSpaceWSImplServiceEndpointEBM
  - Service    : {http://ws.space.dsb.soa4all.eu/}SemanticSpaceWSImplService
  - Interfaces : {http://ws.space.dsb.soa4all.eu/}SemanticSpaceWS,
  - Location (component / container / domain)   : petals-bc-soap / NODE-EBM-00 / subdomain1

/>

… will be extended with more services too.

Here is the Maven descriptor snippet :

<build>
	<plugins>
		<plugin>
			<groupId>org.ow2.petals</groupId>
			<artifactId>maven-petals-wsproxy</artifactId>
			<version>1.0-SNAPSHOT</version>
			<executions>
				<execution>
					<id>generate-jbi</id>
					<phase>package</phase>
					<configuration>
						<wsdl>

http://localhost:8080/Service?wsdl

						</wsdl>
					</configuration>
					<goals>
						<goal>wsproxy</goal>
					</goals>
				</execution>
			</executions>
		</plugin>
	</plugins>
</build>

This will generate a JBI Service Assembly that you can then deploy intoo PEtALS to proxify the service defined in http://localhost:8080/Service?wsdl

You can give it a try, the snapshot version is available on the OW2 Maven repository…

As an example, the following interface :

package org.ow2.petals;
 
import javax.jws.WebMethod;
import javax.jws.WebService;
 
@WebService
public interface Service {
 
	@WebMethod
	String ping(String input);
}

and its implementation :

package org.ow2.petals;
 
public class ServiceImpl implements Service {
	public String ping(String input) {
		return input;
	}
}

will generate a Service Assembly idirectly deployable to PEtALS by the help of the Maven plugin :

<build>
	<plugins>
		<plugin>
			<groupId>org.ow2.petals</groupId>
			<artifactId>maven-petals-jaxws2jbi</artifactId>
			<version>1.0-SNAPSHOT</version>
			<executions>
				<execution>
					<id>generate-jbi</id>
					<phase>package</phase>
					<configuration>
						<className>
							org.ow2.petals.ServiceImpl
						</className>
					</configuration>
					<goals>
						<goal>java2jbi</goal>
					</goals>
				</execution>
			</executions>
		</plugin>
	</plugins>
</build>

The plugin takes the Service class, generates its associated WSDL file and the JBI descriptor and then package all into a Service Assembly.

This work is a result of the ScorWare project in which eBM WebSourcing was involved in.

The SCA feature is provided in PEtALS by the SCA JBI Service Engine (link to the component and link to the documentation)

The main advantage of SCA over other approaches, like BPEL or EIP, is that you can define the composition with Java instead of XML. The SCA composite defines services, which are exposed in the bus. It also defines references, which point to services that might be called or used by the composite at runtime. These references define possible dependencies. And eventually, your composite embeds a Java implementation which allows you to manipulate the references as simple Java objects. This makes the user job easier, in particular to call a service operation or test conditions on a service call result.

For more details on SCA, on tools and more, take a look at the links below :

• SCA is a specification defined by the Open SOA consortium.
• SCA is in standardization process by the OASIS Consortium.
• OW2 FraSCAti is the SCA platform the SCA service engine is based on.
• Eclipse SCA Tools exist and are hosted by the SOA Tools Platform project. They can be used with the SCA service engine.
• PEtALS Eclipse tools complete the STP SCA tools for PEtALS specifics (PEtALS Maven plug-in support, packaging for PEtALS…).

The current article will show you that the JSR181 Service Engine really provides an easy way to create JBI services. Since creating simple HelloWorld service is quite boring, let’s talk to twitter micro blogging site.

I will use the Twitter4J API () to talk to Twitter (right all the Twitter job is done here… The current article is not a Twitter tutorial but just a small PEtALS one…).

Interface definition

package net.chamerling.petals.twitter;
 
import javax.jws.WebMethod;
import javax.jws.WebParam;
import javax.jws.WebService;
 
/**
 * @author chamerling
 *
 */
@WebService
public interface TwitterService {
 
	@WebMethod
	public String update(@WebParam(name = "id") String login,
			@WebParam(name = "password") String password,
			@WebParam(name = "status") String status) throws TwitterServiceException;
 
	@WebMethod
	public String[] getTimeLine(@WebParam(name = "id") String login,
			@WebParam(name = "password") String password,
			@WebParam(name = "user") String user) throws TwitterServiceException;
}

Implementation (quick)

package net.chamerling.petals.twitter;
 
import java.util.ArrayList;
import java.util.List;
 
import javax.jws.WebMethod;
import javax.jws.WebParam;
import javax.jws.WebService;
 
import twitter4j.Status;
import twitter4j.Twitter;
import twitter4j.TwitterException;
 
/**
 * @author chamerling
 *
 */
@WebService(serviceName = "TwitterService", name = "TwitterService", targetNamespace = "http://twitter.chamerling.net/petals")
public class TwitterServiceImpl implements TwitterService {
 
	/*
	 * (non-Javadoc)
	 * @see net.chamerling.petals.twitter.TwitterService#update(java.lang.String, java.lang.String, java.lang.String)
	 */
	@WebMethod
	public String update(@WebParam(name = "id") String login,
			@WebParam(name = "password") String password,
			@WebParam(name = "status") String status) throws TwitterServiceException {
		String result = null;
		try {
			Status s = getTwitter(login, password).update(status);
			result = s.getText();
		} catch (twitter4j.TwitterException e) {
			throw new TwitterServiceException(e.getMessage());
		}
		return result;
	}
 
	/*
	 * (non-Javadoc)
	 * @see net.chamerling.petals.twitter.TwitterService#getTimeLine(java.lang.String, java.lang.String, java.lang.String)
	 */
	@WebMethod
	public String[] getTimeLine(@WebParam(name = "id") String login,
			@WebParam(name = "password") String password,
			@WebParam(name = "user") String user) throws TwitterServiceException {
		Twitter twitter = getTwitter(login, password);
		List result = new ArrayList();
		List status = null;
		try {
			if (user == null) {
				status = twitter.getUserTimeline();
			} else {
				status = twitter.getUserTimeline(user);
			}
		} catch (TwitterException e) {
			throw new TwitterServiceException(e.getMessage());
		}
 
		for (Status status2 : status) {
			result.add(status2.getText());
		}
 
		return result.toArray(new String[0]);
	}
 
	/**
	 * TODO : Some work to do for caching...
	 * 
	 * @param login
	 * @param password
	 * @return
	 */
	private Twitter getTwitter(String login, String password) {
		return new Twitter(login, password);
	}
}

Put all of this in a JSR181 Service Unit, ie create the good Service Unit descriptor (cf to source attchment), package it (use PEtALS Maven plugin) and that’s all. JSR181 makes it easy ;o)

So now you can publish some status to Twitter with PEtALS.
I have created a test acount here http://twitter.com/chamerlingtest on which I have published messages with PEtALS.

Service Unit sources are available here : http://dl.getdropbox.com/u/73785/blog/twitter-jsr181.zip

Today, I spent some time on a customer bug which was not really a bug… I was quite surprising when he said me that he was unable to get its annotated class working on the component. The error was at instantiation time (first JBI message handling) :

org.apache.axis2.AxisFault: The service is unable to load the foo.bar.Service service implementation class. at org.apache.axis2.AxisFault.makeFault(AxisFault.java:430) at org.apache.axis2.jaxws.server.JAXWSMessageReceiver.receive(JAXWSMessageReceiver.java:220) at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:176) at org.ow2.petals.se.jsr181.JBIListener.onJBIMessage(JBIListener.java:120) at org.ow2.petals.component.framework.listener.MessageExchangeProcessor.processInOutAsProvider(MessageExchangeProcessor.java:524) at org.ow2.petals.component.framework.listener.MessageExchangeProcessor.processAsProvider(MessageExchangeProcessor.java:421) at org.ow2.petals.component.framework.listener.MessageExchangeProcessor.process(MessageExchangeProcessor.java:308) at org.ow2.petals.component.framework.listener.MessageExchangeProcessor.run(MessageExchangeProcessor.java:145) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907) at java.lang.Thread.run(Thread.java:619) Caused by: javax.xml.ws.WebServiceException: The service is unable to load the org.ow2.petals.usecase.jsr181.TestService service implementation class. at org.apache.axis2.jaxws.ExceptionFactory.createWebServiceException(ExceptionFactory.java:173) at org.apache.axis2.jaxws.ExceptionFactory.makeWebServiceException(ExceptionFactory.java:70) at org.apache.axis2.jaxws.ExceptionFactory.makeWebServiceException(ExceptionFactory.java:118) at org.apache.axis2.jaxws.server.endpoint.lifecycle.impl.EndpointLifecycleManagerImpl.createServiceInstance(EndpointLifecycleManagerImpl.java:242) at org.apache.axis2.jaxws.server.endpoint.lifecycle.impl.EndpointLifecycleManagerImpl.createServiceInstance(EndpointLifecycleManagerImpl.java:94) at org.apache.axis2.jaxws.server.ServiceInstanceFactoryImpl.createServiceInstance(ServiceInstanceFactoryImpl.java:49) at org.apache.axis2.jaxws.server.EndpointController.handleRequest(EndpointController.java:253) at org.apache.axis2.jaxws.server.EndpointController.invoke(EndpointController.java:98) at org.apache.axis2.jaxws.server.JAXWSMessageReceiver.receive(JAXWSMessageReceiver.java:159) … 9 more

So what? I launched PEtALS in debug mode, and going step by step until the foo.bar.Service class instantiation. ‘Hey what’s up InstanciationException?’.
This is simply because the foo.bar.Service class contains constructors and not the empty one!

The solution is to remove all the constructors which are not very usefull here (since they can not be used), or add an empty constructor. Now it works!

Create the project structure

(I assume that Maven is installed and is in the path, if not please refer to the Apache Maven website).

mvn archetype:create
-DarchetypeGroupId=org.ow2.petals
-DarchetypeArtifactId=maven-archetype-petals-jbi-service-engine
-DarchetypeVersion=1.3.0-SNAPSHOT
-DgroupId=com.ebmws.petals
-DartifactId=petals-se-sample
-Dversion=1.0-SNAPSHOT

This will create the standard component structure.
You can check the JBI descriptor in petals-se-sample/src/main/jbi. Note that some fields such as the classpath are automatically filled during the packaging phase from the dependencies specified in your POM descriptor.

Create the Eclipse project

cd petals-se-sample
mvn eclipse:eclipse

In Eclipse, import the project and you will get

Do your business code

Now in the JBIListener class, you can implement the business logic which will be called when a JBI message is received in the activated JBI Endpoind (How to activate endpoint will come in the next article).

For example, just say hello to the world in the JBIListener like this :

Package the component

Simply package it with
mvn install

You will get a ZIP archive in the target directory which is the component you can deploy in PEtALS container

The source of this component are available here http://christophe.hamerling.free.fr/ebm/blog/tuto/cdk/petals-se-sample.zip