To create a Java web service, a service endpoint interface (SEI) and implementation class must be defined. SEI defines the Java class methods to be exposed as web service operations. The implementation class contains the actual implementation of the SEI. The following SEI defines the web service operations, echoString and echoString_double.

package jeustest.webservices.java2wsdl.doclit;

public interface Echo extends java.rmi.Remote {
    public String echoString(String arg11)
        throws java.rmi.RemoteException;
    public String echoString_double(String arg1, String arg2)
        throws java.rmi.RemoteException;
}

As mentioned already, SEI specifies which web service operations are exposed for external access through the SOAP protocol. An SEI should directly or indirectly extend the java.rmi.Remote interface and each method should throw a java.rmi.RemoteException exception. After the web service operations are defined, their actual logic must be implemented in the implementation class.

The following is an example of an implementation class.

package jeustest.webservices.java2wsdl.doclit;

public class EchoImpl implements Echo {
    public String echoString(String input0)
        throws java.rmi.RemoteException {
        return input0;
    }

    public String echoString_double(String input0, String input1)
        throws java.rmi.RemoteException {
        return input0+input1;
    }
}

The implementation class implements the SEI. It is instantiated and executed on the JavaEE server, and runs as a web service at runtime.

The following principles must be followed when creating a back-end Java web service.

When aforementioned principles have been satisfied, create a web service by using the following steps.

A stateless session EJB can also be exported as a web service, and it also requires an SEI.

The following SEI (HelloIF.java) defines a web service operation called sayHello(String).

package helloejb;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface HelloIF extends Remote {
    public String sayHello(String s) throws RemoteException;
}

An SEI defines the web service operations to be exposed for external access through the SOAP protocol. An SEI should directly or indirectly extend the java.rmi.Remote interface, and each method must throw the java.rmi.RemoteException exception. After the web service operations are defined, the actual logic must be implemented in the implementation class. In the following example, an EJB is used as the implementation class.

The following is an example of a remote interface class.

package helloejb;

import javax.ejb.EJBObject;
import java.rmi.RemoteException;

public interface Hello extends EJBObject
{
    String sayHello(String s) throws RemoteException;
}

The following is the home interface class.

package helloejb;

import java.io.Serializable;
import java.rmi.RemoteException;
import javax.ejb.CreateException;
import javax.ejb.EJBHome;

public interface HelloHome extends EJBHome
{
    Hello create() throws RemoteException, CreateException;
}

The following is the EJB endpoint bean class that contains the implementation of the session bean.

package helloejb;

import java.rmi.RemoteException;

import javax.ejb.SessionBean;
import javax.ejb.SessionContext;
import java.lang.*;

public class HelloEJB implements SessionBean {

    public HelloEJB() {}
    public String sayHello(String s) throws RemoteException {
        try {
            Thread.currentThread().sleep(500);
        } catch (Exception ex) {
            throw new RemoteException("" + ex);
        }
        return "Hello World!" + s;
    }
    public void ejbCreate() {}
    public void ejbRemove() throws RemoteException {}
    public void setSessionContext(SessionContext sc) {}
    public void ejbActivate() {}
    public void ejbPassivate() {}
}

If the web service operation is configured as 'one-way', the EJB method's return type must be 'void'. Otherwise, developing a stateless session EJB web service is not different from developing a general EJB.

When the aforementioned principles have been satisfied, create a web service in the following steps.