Petals-SE-Jsr181 1.6.0+

Version 1 by Christophe DENEUX
on Mar 12, 2018 12:13.

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Current by Christophe DENEUX
on Mar 30, 2018 12:45.

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{warning}This version must be installed on [Petals ESB 5.2.0|petalsesb520:Petals ESB 5.2.0]+{warning}

h1. Features

This service engine allows to create a Petals service from an annotated Java class.
The annotations are the ones defined by the [JSR-181 specification|http://jcp.org/en/jsr/detail?id=181|http://jcp.org/en/jsr/detail?id=181], although most of the JAX-WS annotations are supported, Apache Axis2 is used by the component.

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This component can only expose services in Petals ESB.
The invocation of Petals services from the annotated class is experimental and will not be discussed here.
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h1. Creating an hard-coded service

This section explains how to create a hard-coded service, that will run on the JSR-181 component.

JSR-181 proposes an easy way to define the service you want to expose via Java annotations.

h2. Service-Unit content

A service-unit for this component must contain:
* One or several JAR files, containing at least one Java annotated class.
* A WSDL definition, that is coherent with the Java class. The best way to ensure that is to generate the WSDL from the annotated class.
* A JBI descriptor.

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The directory structure of a SU for the Petals-SE-Jsr81 looks like this:

{noformat}
su-jsr181-ServiceName-provide.zip
+ META-INF
- jbi.xml
+ Service.wsdl
+ ServiceImplementation.jar (one or several)
{noformat}

h2. The Service implementation

The service is implemented by Java class which must be annotated with JSR-181 annotations (@WebService to be exact).
Every parameter must be a Java bean, with a public zero-argument constructor.
The important thing to take care is the way objects will be marshalled and unmarshalled, i.e. the transformation between the XML messages than come from and to Petals, and the Java objects the service implementation will deal with. This is why all your parameters should respect the Java bean conventions.

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The service operation will be the class methods.
You are strongly encouraged to annotate every element of the class, so that the generated WSDL is easy to read.
The WSDL should be generated from the annotated class. Tools like *wsgen* make this task easy (or you can use Petals Studio too).

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Here is a sample annotated class:

{code:lang=java}
package org.ow2.petals.usecase.jsr181;

import java.text.SimpleDateFormat;
import java.util.Date;
import javax.jws.WebMethod;
import javax.jws.WebService;

/**
* @author Christophe Hamerling - EBM WebSourcing
*/
@WebService(serviceName = "Hello", name = "MyService", targetNamespace = "http://petals.ow2.org")
public class TestService {

/**
* Say hello to the world!
*/
@WebMethod
public String sayHello( String str ) {
System.out.println( "Hey! This is the sayHello operation." );
return "You told me: " + str;
}

/**
* Gets a person from its id only to test 'complex' data binding.
*
* @param id
* @return
*/
@WebMethod
public Person getPerson( int id ) {
System.out.println( "Get person " + id );
return new Person( id, "Christophe", "Hamerling", 29, "France" );
}

/**
*
* @return
*/
@WebMethod
public String getTime() {
System.out.println( "Get time" );
return new SimpleDateFormat().format( new Date( System.currentTimeMillis()));
}

/**
* NOP
*/
@WebMethod
public void voidvoid() {
System.out.println( "The Void operation" );
}

/**
* The final WSDL operation will be 'specializedOperation'
*/
@WebMethod(operationName = "specializedOperation")
public void operation() {
System.out.println( "The specialized operation" );
}

/**
*
* @throws Exception
*/
@WebMethod
public String iAmThrowingAnException() throws Exception {
System.out.println( "throw exception" );
throw new Exception( "This is a server side Exception" );
}

/**
* Gets a list of persons.
*/
@WebMethod
public List<Person> getPersons() {
...
}
}
{code}

The main annotations you may use are:
* The *@WebService* annotation is *mandatory* and is used by the Axis2 engine to build the service. You can specialize the service name, target namespace and more with the annotation parameter.
* The *@WebMethod* annotation is used to delare the that the method will be seen as a JBI operation. You can specialize the operation name and more with the annotation parameters.
* The *@WebParam* annotation is used to configure an operation parameter.

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{tip}
If one your method returns a collection of beans, do not forget to annotate the fields of the bean class with *@XmlAttribute*.
Otherwise, the WSDL generation will be incomplete (missing elements in the XML schemas).
{tip}

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{code:lang=java}
public class Person {

public enum Sex {
F ("Female"),M("Male");

private String textToDisplay;

Sex(String text) {
this.textToDisplay = text;
}

@Override
public String toString() {
return this.textToDisplay;
}
}

@XmlElement
private String firstName;

@XmlElement
private String surname;

@XmlElement
private Calendar birthday;

@XmlElement
private Sex sex;

public Person() {
this.firstName = null;
this.surname = null;
this.birthday = null;
this.sex = null;
}

public String getFirstName() {
return firstName;
}

public String getSurname() {
return surname;
}

public Calendar getBirthday() {
return birthday;
}

public Sex getSex() {
return sex;
}
}
{code}

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There are many more annotations to use with JAX-WS.
More information is available on the [Apache Axis2 page|http://ws.apache.org/axis2/].

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In fact, for each annotated class, the Petals Jsr181 component creates an Axis2 service.
The messages that are received from the bus are then forwarded to the right Axis2 service the component holds.
Before forwarding the JBI message to the Axis2 service, the service engine checks that :
* The requested operation exists in the Axis2 service. If not, an error will be returned in the JBI message exchange.
* The JBI Message Exchange Pattern (MEP) is compatible with the target operation. For example, in the previous code snippet, an InOut MEP is not compatible with the 'voidvoid' operation and an error would be returned in the JBI message exchange.

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It is not possible to only provide the Java class.
The component needs the annotated class, the associated WSDL and a JBI descriptor.
This descriptor references WSDL elements. You mandatory need to have generated the WSDL.

h2. Service-Unit descriptor

The service-unit descriptor file (jbi.xml) looks like this:
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{code:lang=xml}
<?xml version="1.0" encoding="UTF-8"?>
<jbi:jbi version="1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:jbi="http://java.sun.com/xml/ns/jbi"
xmlns:petalsCDK="http://petals.ow2.org/components/extensions/version-5"
xmlns:helloworld="http://petals.ow2.org/helloworld"
xmlns:jsr181="http://petals.ow2.org/components/jsr181/version-1">

<jbi:services binding-component="false">
<jbi:provides
interface-name="helloworld:Helloworld"
service-name="helloworld:HelloworldService"
endpoint-name="HelloworldEndpoint">
<petalsCDK:wsdl>Service.wsdl</petalsCDK:wsdl>
<jsr181:class>org.ow2.petals.usecase.jsr181.TestService</jsr181:class>
</jbi:provides>
</jbi:services>
</jbi:jbi>
{code}

{include:0 CDK SU Provide Configuration 5.7.0}

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{center}*Configuration of a Service Unit to provide a service (JSR-181)*{center}

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Petals-SE-Jsr181 1.6.0+

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