amber (jpa)
ejb
database
ioc
jmx
jsf
messaging
quercus
remoting
servlet
security

hessian serialization
hessian addition
service addition
hessian with di
burlap addition
custom-protocol
simple service
client injection

a simple service for resin remoting

Writing a service for the Resin remoting as a plain-old Java object (POJO) eliminates protocol dependencies and simplifies service testing.

Demo

See Also

Files in this tutorial

Introduction

Service Interface

Service Implementation

Service configuration

Client configuration

JSP Client Script

PHP Client Script

With the Resin remoting, services can be written as plain-old Java objects (POJOs) and made available to many different protocols using simple configuration changes.

Files in this tutorial

FILE	DESCRIPTION
WEB-INF/classes/example/HelloService.java	Interface for the hello service.
WEB-INF/classes/example/HelloServiceImpl.java	The main service implementation.
WEB-INF/resin-web.xml	Configures the environment
demo.jsp	Client JSP
demo.php	Client PHP

Introduction

The Resin remoting is an infrastructure that allows a service to be exposed via many different service protocols. For example in this tutorial, there is a plain-old Java object (POJO) that implements a service and this service is made available using REST, SOAP, Hessian, and WebBeans. The service is implemented once and these protocols are activated with a few simple changes to the configuration file.

Service Interface

In this example, the service interface is for a simple Hello, World service. There is a single method, hello() that the service must implement and the client may invoke.

HelloService.java

package example;

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

Service Implementation

The HelloService implementation is just a Java class that implements the HelloService API. It can optionally use EJB annotations like @Remote, @Stateless or @TransactionAttribute.

HelloServiceImpl.java

package example;

public class HelloServiceImpl implements HelloService {
  /**
   * Returns "hello, world".
   */
  public String hello()
  {
    return "hello, world";
  }
}

Service configuration

Services for Resin remoting are configured with the <servlet> tag. The implementation class is given as the servlet-class attribute. It is possible to allow access to the service within the same virtual machine by registering the service as a WebBeans singleton with <bean>.

To expose the service as a Hessian service, use the <hessian> tag. Hessian is one of the protocols available for web services.

Finally, a SOAP interface is available, using CXF or XFire.

remoting service for hessian

<web-app xmlns="http://caucho.com/ns/resin">

  <servlet-mapping url-pattern="/hello/hessian/*"
                   servlet-class="example.HelloServiceImpl">
    <protocol uri="hessian:"/>
  </servlet-mapping>

</web-app>

remote service for CXF

<web-app xmlns="http://caucho.com/ns/resin">

  <servlet-mapping url-pattern="/hello/hessian/*"
                   servlet-class="example.HelloServiceImpl">
    <protocol uri="cxf:"/>
  </servlet-mapping>

</web-app>

service as WebBeans singleton

<web-app xmlns="http://caucho.com/ns/resin">

  <bean class="example.HelloServiceImpl" name="vm"/>

</web-app>

Client configuration

Resin also makes it easy to access services using the <remote-client> tag. This tag connects to a service using a URI of the form <protocol>:url=<location>. The example below shows just such a URL. The interface of the service is required. The <remote-client> tag creates a proxy client instance for the service and registers the proxy with WebBeans.

<remote-client>

<web-app xmlns="http://caucho.com/ns/resin">

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

  <remote-client interface="example.HelloService" name="rest">
    <uri>rest:url=${webApp.url}/hello/rest/</uri>
  </web-service-client>

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

</web-app>

JSP Client Script

The client can now connect to the HelloService using any supported encoding simply by doing a WebBeans injection.

demo.jsp

<%@ page import="javax.webbeans.Named" %>
<%@ page import="example.HelloService" %>
<%!
@Named("hessian") HelloService _hessianHello;
@Named("rest") HelloService _restHello;
@Named("soap") HelloService _soapHello;
@Named("vm") HelloService _vmHello;
%>
<pre>
From Hessian: <%= _hessianHello.hello() %>
From REST: <%= _restHello.hello() %>
From SOAP: <%= _soapHello.hello() %>
From VM: <%= _vmHello.hello() %>
</pre>

From Hessian: hello, world
From REST: hello, world
From SOAP: hello, world
From VM: hello, world

PHP Client Script

The client can now connect to the HelloService using PHP with the java_bean() method.

demo.php

<?php
$hessian = java_bean("hessian");
$rest = java_bean("rest");
$soap = java_bean("soap");
$vm = java_bean("vm");
?>
<pre>
From Hessian: <?= $hessian->hello() ?>
From REST: <?= $rest->hello() ?>
From SOAP: <?= $soap->hello() ?>
From VM: <?= $vm->hello() ?>
</pre>

From Hessian: hello, world
From REST: hello, world
From SOAP: hello, world
From VM: hello, world