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a frontend client for a hessian service


This tutorial shows how to access services with Resin WebBeans injection. A servlet does frontend presentation for the results of a Hessian web service.

Files in this tutorial

FILEDESCRIPTION
WEB-INF/classes/example/HelloService.javaInterface for the hello service.
WEB-INF/classes/example/HelloServiceImpl.java
WEB-INF/classes/example/ServiceFrontendServlet.javaThe main service implementation.
WEB-INF/resin-web.xmlConfigures the environment
demo.jspClient JSP

Service Interface and Configuration

The service used in this example is the same hello world service used in the simple service tutorial. The interface used by the frontend is shown below.

HelloService.java
package example;

public interface HelloService {
  /**
   * Returns "hello, world".
   */
  public String hello();
}

Configuring the service is also the same as in the the simple service tutorial.

<servlet>
<servlet-mapping url-pattern="/hello/*"
                 servlet-class="example.HelloServiceImpl"
                 jndi-name="service/HelloService">

  <protocol uri="hessian:"/>
</servlet-mapping>

Frontend Client

The client in this case is simply a servlet that uses J2EE injection to access the service.

ServiceFrontendServlet.java
package example;

import java.io.*;
import javax.annotation.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ServiceFrontendServlet extends HttpServlet {
  @Named("hessian")
  private HelloService _helloService;

  public void doGet(HttpServletRequest req, HttpServletResponse resp)
    throws IOException, ServletException
  {
    PrintStream out = new PrintStream(resp.getOutputStream());

    out.println("service result: " + _helloService.hello());
  }
}

Configuring the client is nearly the same as in the the simple service tutorial, the only difference being adding the mapping for the servlet.

Client configuration
<remote-client name="hessian">
  <uri>hessian:url=${webApp.url}/hello/</uri>
  <interface>example.HelloService</interface>
</remote-client>

<servlet servlet-name="service-frontend" 
         servlet-class="example.ServiceFrontendServlet" />
<servlet-mapping url-pattern="/frontend/" servlet-name="service-frontend" />

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