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TOTD #4: How to convert a Session EJB to a Web service ?

Posted by arungupta on August 23, 2007 at 6:09 AM PDT

This TOTD describes
how to convert a stateless session EJB to a Web service and uses information
from this
thread
.

  1. Add @javax.jws.WebService annotation at the top of your EJB
    class. The modified code looks like:



    @javax.ejb.Stateless

    @javax.jws.WebService

    public class HelloSessionBean implements server.HelloSessionLocal {

        public String sayHello(String name) {

            return "Hello " + name + " from
    session bean";

        }

    }



    The new annotation is shown in this color.
  2. Re-build your project and redeploy it.

That's it!

There is no need to specify any additional deployment descriptor or
parameters.The WSDL exposed by the EJB Web service endpoint is available at "http://localhost:8080/HelloSessionBeanService/HelloSessionBean?wsdl".
The generated WSDL looks like:

<?xml version="1.0" encoding="UTF-8"?>

<!-- Published by JAX-WS RI at http://jax-ws.dev.java.net. RI's version is JAX-WS
RI 2.1.2-hudson-182-RC1. -->

<!-- Generated by JAX-WS RI at http://jax-ws.dev.java.net. RI's version is JAX-WS
RI 2.1.2-hudson-182-RC1. -->

<definitions

  xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"

  xmlns:wsp="http://schemas.xmlsoap.org/ws/2004/09/policy"

  xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"

  xmlns:tns="http://server/"

  xmlns:xsd="http://www.w3.org/2001/XMLSchema"

  xmlns="http://schemas.xmlsoap.org/wsdl/"

  targetNamespace="http://server/"

  name="HelloSessionBeanService">

  <wsp:UsingPolicy></wsp:UsingPolicy>

  <wsp:Policy wsu:Id="HelloSessionBeanPortBinding_sayHello_WSAT_Policy">

    <wsp:ExactlyOne>

      <wsp:All>

        <ns1:ATAlwaysCapability
xmlns:ns1="http://schemas.xmlsoap.org/ws/2004/10/wsat" wsp:Optional="false"></ns1:ATAlwaysCapability>

        <ns2:ATAssertion xmlns:ns3="http://schemas.xmlsoap.org/ws/2002/12/policy"


                         xmlns:ns2="http://schemas.xmlsoap.org/ws/2004/10/wsat" ns3:Optional="true"


                         wsp:Optional="true"></ns2:ATAssertion>

      </wsp:All>

    </wsp:ExactlyOne>

  </wsp:Policy>

  <types>

    <xsd:schema>

      <xsd:import namespace="http://server/"
schemaLocation="http://localhost:8080/HelloSessionBeanService/HelloSessionBean?xsd=1"></xsd:import>

    </xsd:schema>

  </types>

  <message name="sayHello">

    <part name="parameters" element="tns:sayHello"></part>

  </message>

  <message name="sayHelloResponse">

    <part name="parameters" element="tns:sayHelloResponse"></part>

  </message>

  <portType name="HelloSessionBean">

    <operation name="sayHello">

      <input message="tns:sayHello"></input>

      <output message="tns:sayHelloResponse"></output>

    </operation>

  </portType>

  <binding name="HelloSessionBeanPortBinding" type="tns:HelloSessionBean">

    <soap:binding transport="http://schemas.xmlsoap.org/soap/http"
style="document"></soap:binding>

    <operation name="sayHello">

      <wsp:PolicyReference URI="#HelloSessionBeanPortBinding_sayHello_WSAT_Policy"></wsp:PolicyReference>

      <soap:operation soapAction=""></soap:operation>

      <input>

        <soap:body use="literal"></soap:body>

      </input>

      <output>

        <soap:body use="literal"></soap:body>

      </output>

    </operation>

  </binding>

  <service name="HelloSessionBeanService">

    <port name="HelloSessionBeanPort" binding="tns:HelloSessionBeanPortBinding">

      <soap:address location="http://localhost:8080/HelloSessionBeanService/HelloSessionBean"></soap:address>

    </port>

  </service>

</definitions>

Few points to notice:

  1. A reasonable set of defaults are chosen for portType/@name,
    binding/@name, service/@name and even the soap:address/@location. Most of these values can be changed by specifying
    a different value in the @WebService annotation.

  2. Accordingly to EJB 3.0 specification, if @TransactionAttribute
    is not specified on the method then a default value of REQUIRED
    is applied. This default value is automatically converted to

    	ATAlwaysCapability
    and ATAssertion policy assertions.

  3. Accordingly to

    Web Services for Java EE, Version 1.2
    , webservices.xml is
    optional so there is no need to write any other deployment descriptor.

  4. Be careful not to deploy a WAR file with the context root
    generated (HelloSessionBeanService) for the Web service
    endpoint. The EJB Web service endpoint will be inaccessible after that.

Please leave suggestions on other TOTD that you'd like to see. A
complete archive is available
here
.

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