Every EJB endpoint must have a WSDL document that describes the web service. The <portType> declared by the WSDL document must be aligned with the endpoint interface of the web service. In other words, the mapping between the WSDL <portType> and the endpoint interface must be correct according to the JAX-RPC specification. One way to accomplish this is to create the WSDL document first, and then use it to generate the endpoint interface:

<?xml version="1.0"?>
<definitions name="TravelAgent"
   xmlns="http://schemas.xmlsoap.org/wsdl/"
   xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"
   xmlns:titan="http://www.titan.com/TravelAgent"
   targetNamespace="http://www.titan.com/TravelAgent">

<!-- message elements describe the parameters and return values -->
<message name="RequestMessage">
   <part name="cruiseId"   type="xsd:int" />
   <part name="cabinId"    type="xsd:int" />
   <part name="customerId" type="xsd:int" />
   <part name="price"      type="xsd:double" />
</message>
<message name="ResponseMessage">
   <part name="reservationId" type="xsd:string" />
</message>

<!-- portType element describes the abstract interface of a web service -->
<portType name="TravelAgentEndpoint">
  <operation name="makeReservation">
     <input message="titan:RequestMessage"/>
     <output message="titan:ResponseMessage"/>
  </operation>
</portType>

<!-- binding element tells us which protocols and encoding styles are used  -->
<binding name="TravelAgentBinding" type="titan:TravelAgentEndpoint">
   <soap:binding style="rpc" 
                 transport="http://schemas.xmlsoap.org/soap/http"/>
   <operation name="makeReservation">
      <soap:operation soapAction="" /> 
      <input>
        <soap:body use="literal" 
              namespace="http://www.titan.com/TravelAgent"/>
      </input>
      <output>
        <soap:body use="literal" 
              namespace="http://www.titan.com/TravelAgent"/>
      </output>
   </operation>
</binding>

<!-- service element tells us the Internet address of a web service -->
<service name="TravelAgentService">
  <port name="TravelAgentPort" binding="titan:TravelAgentBinding">
     <soap:address location="http://www.titan.com/webservices/TravelAgent" /> 
  </port>
</service>

</definitions>

Based on this WSDL document, we can generate a JAX-RPC endpoint interface, which will be implemented by our EJB endpoint. The endpoint interface is generated from the <portType> and <message> definitions (and <types>, if present). The endpoint interface looks like this:

package com.titan.webservice;

public interface TravelAgentEndpoint extends java.rmi.Remote {
    public java.lang.String makeReservation(int cruiseId, int cabinId, 
                                            int customerId, double price) 
    throws java.rmi.RemoteException;
}

The endpoint interface defines the business methods that will be accessible as SOAP operations. The interface extends java.rmi.Remote—there is no EJBObject interface—and defines one or more business methods, each of which must throw a java.rmi.RemoteException. The types that can be used as parameters and return types are the same types that can be used with JAX-RPC generated endpoints (see Table 15-1). You can also use simple Java bean types for holding complex data.

An EJB endpoint does not define a home interface; there is no EJB home object for creating or locating EJB endpoints. An EJB endpoint cannot be created or located; it’s a truly stateless service, both semantically and physically. The only time an EJB would have a home interface is if the EJB defined remote or local interfaces in addition to the endpoint interface. In other words, a single EJB can be local, remote, and an endpoint.

The bean class defined for the TravelAgent endpoint must implement the methods defined by the endpoint interface. A stateless bean class can implement the endpoint interface directly—something that’s not recommended for the local or remote interfaces. That’s because the endpoint interface is a direct descendent of java.rmi.Remote, and doesn’t define any EJBObject methods. Here’s the new definition for the TravelAgent bean class:

package com.titan.webservice;
import com.titan.reservation.*;
import com.titan.cruise.*;
import com.titan.customer.*;
import com.titan.cabin.*;
import com.titan.processpayment.*;
import java.rmi.RemoteException;
import javax.rmi.PortableRemoteObject;
import javax.naming.NamingException;
import javax.ejb.EJBException;
import java.util.Date;
import java.util.Calendar;

public class TravelAgentBean 
                      implements TravelAgentEndpoint, javax.ejb.SessionBean {
    public javax.naming.Context jndiContext;

    public void ejbCreate( ) {}

    public String makeReservation(int cruiseId, int cabinId, 
                                  int customerId, double price){
                  try {
                  CruiseLocal cruise = this.getCruise(cruiseId);
                  CabinLocal cabin = this.getCabin(cabinId);           
                  CustomerRemote customer = this.getCustomer(customerId);
                  CreditCardDO card = this.getCreditCard(customerId);
   
                  ReservationHomeLocal resHome = (ReservationHomeLocal)            
                  jndiContext.lookup("java:comp/env/ejb/ReservationHomeLocal");
                  ReservationLocal reservation =
                  resHome.create(customer, cruise, cabin, price, new Date( ));
                  Object ref = jndiContext.lookup(
                         "java:comp/env/ejb/ProcessPaymentHomeRemote");
                  ProcessPaymentHomeRemote ppHome = (ProcessPaymentHomeRemote)
                  PortableRemoteObject.narrow(ref, ProcessPaymentHomeRemote.class);
            
                  ProcessPaymentRemote process = ppHome.create( );
                  process.byCredit(customer, card, price);

                  return reservation.getPrimaryKey( ).toString( );

                  } catch(Exception e) {
                  throw new EJBException(e);
                  }
                  }

    public CustomerRemote getCustomer(int customer_id) throws Exception { 
        Integer customerID = new Integer(customer_id);
        CustomerHomeRemote home = (CustomerHomeRemote)
                jndiContext.lookup("java:comp/env/ejb/CustomerHomeRemote");
            
        return home.findByPrimaryKey(customerID);
    }
    public CreditCardDO getCreditCard(int customer_id) throws Exception{
        Integer customerID = new Integer(customer_id);
        CustomerHomeLocal home = (CustomerHomeLocal)
                jndiContext.lookup("java:comp/env/ejb/CustomerHomeLocal");
            
        CustomerLocal customer = home.findByPrimaryKey(customerID);
        CreditCardLocal card = customer.getCreditCard( );
        return new CreditCardDO(card.getNumber( ),card.getExpirationDate( ),
                                card.getCreditOrganization( ));
    }
    public CabinLocal getCabin(int cabin_id) throws Exception { 
        Integer cabinID = new Integer(cabin_id);
        CabinHomeLocal home = (CabinHomeLocal)
             jndiContext.lookup("java:comp/env/ejb/CabinHomeLocal");
            
        return home.findByPrimaryKey(cabinID);
    }
    public CruiseLocal getCruise(int cruise_id) throws Exception { 
        Integer cruiseID = new Integer(cruise_id);
        CruiseHomeLocal home = (CruiseHomeLocal)
               jndiContext.lookup("java:comp/env/ejb/CruiseHomeLocal");
           
        return home.findByPrimaryKey(cruiseID);
    }
    public void ejbRemove( ) {}
    public void ejbActivate( ) {}
    public void ejbPassivate( ) {}   
    public void setSessionContext(javax.ejb.SessionContext cntx){
        try {
            jndiContext = new javax.naming.InitialContext( );
        }catch(NamingException ne) {
            throw new EJBException(ne);
        }
    }
}

The TravelAgentBean class is not that different from the TravelAgent EJB developed earlier in this chapter (the version that uses the Charge-It credit card processing web service). The primary difference is that it responds to web service calls, rather than remote or local calls.

The TravelAgent endpoint requires four deployment files: a standard ejb-jar.xml deployment descriptor, a WSDL file, a JAX-RPC mapping file, and a webservices.xml file.

<?xml version='1.0' encoding='UTF-8' standalone='yes'?>
<ejb-jar 
     xmlns="http://java.sun.com/xml/ns/j2ee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
                         http://java.sun.com/xml/ns/j2ee/ejb-jar_2_1.xsd"
     version="2.1">
    <enterprise-beans>
        <session>
            <description>
                A Web Service reservation service
            </description>
            <ejb-name>TravelAgentEjbEndpoint</ejb-name>
                     <service-endpoint>
                     com.titan.webservice.TravelAgentEndpoint
                     </service-endpoint>
                     <ejb-class>
                     com.titan.webservice.TravelAgentBean
                     </ejb-class>
                     <session-type>Stateless</session-type>
                     <transaction-type>Container</transaction-type>
            <ejb-ref>
                <ejb-ref-name>ejb/ProcessPaymentHomeRemote</ejb-ref-name>
                <ejb-ref-type>Session</ejb-ref-type>
                <home>com.titan.processpayment.ProcessPaymentHomeRemote</home>
                <remote>com.titan.processpayment.ProcessPaymentRemote</remote>
            </ejb-ref>
            ...
        </session>
        ...
    </enterprise-beans>
    <assembly-descriptor>
        ...
    </assembly-descriptor>
</ejb-jar>

<?xml version='1.0' encoding='UTF-8' ?>
<java-wsdl-mapping
  xmlns="http://java.sun.com/xml/ns/j2ee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
               http://www.ibm.com/webservices/xsd/j2ee_jaxrpc_mapping_1_1.xsd"
  version="1.1">
  <package-mapping>
    <package-type>com.titan.webservice</package-type>
                         <namespaceURI>http://www.titan.com/TravelAgent</namespaceURI>
  </package-mapping>
</java-wsdl-mapping>

<?xml version='1.0' encoding='UTF-8' ?>
<webservices 
   xmlns="http://java.sun.com/xml/ns/j2ee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:titan="http://www.titan.com/TravelAgent"
   xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
                 http://www.ibm.com/webservices/xsd/j2ee_web_services_1_1.xsd"
   version="1.1">

      <webservice-description>
         <webservice-description-name>TravelAgentService
         </webservice-description-name>
         <wsdl-file>/META-INF/travelagent.wsdl</wsdl-file>
         <jaxrpc-mapping-file>/META-INF/travelagent_mapping.xml
         </jaxrpc-mapping-file>
         <port-component>
            <port-component-name>TravelAgentEndpoint</port-component-name>
            <wsdl-port>titan:TravelAgentPort</wsdl-port>
            <service-endpoint-interface>
               com.titan.webservice.TravelAgentEndpoint
            </service-endpoint-interface>
            <service-impl-bean>
               <ejb-link>TravelAgentEjbEndpoint</ejb-link>
            </service-impl-bean>
         </port-component>
      </webservice-description>
</webservices>