We may use the HessianServiceExporter and HessianProxyFactoryBean classes to implement the hessian remoting service. The major advantage of Hessian’s is that Hessian works well on both sides of a firewall. Hessian is a portable language that may be used with other languages like PHP and.Net.
Implementation: To make a simple hessian application, you’ll need to make the following files:
- Calculation.java
- CalculationImpl.java
- web.xml
- hessian-servlet.xml
- client-beans.xml
- Client.java
The project structure looks as follows:
A. File: Calculation.java
Java
// Java Program to illustrate Simple Interface// Containing one method cube. package com.neveropen; // Interfacepublic interface Calculation { int cube(int number);} |
B. File: CalculationImpl.java
Java
// Java Program to Illustrate Implementation// of the Calculation interface package com.neveropen; // Class// Implementing interfacepublic class CalculationImpl implements Calculation { // Method public int cube(int number) { // Returning cube of a number return number * number * number; }} |
C. File: web.xml
The front controller is defined in this XML file called DispatcherServlet. Any request that ends in.http will be routed to DispatcherServlet.
XML
<?xml version="1.0" encoding="UTF-8"?><web-app> <servlet> <servlet-name>hessian</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup></servlet> <servlet-mapping> <servlet-name>hessian</servlet-name> <url-pattern>*.http</url-pattern></servlet-mapping></web-app> |
D. File: hessian-servlet.xml
It has to be placed in the WEB-INF folder. It must be called servletname-servlet.xml. It specifies CalculationImpl and HessianServiceExporter as beans.
XML
<?xml version="1.0" encoding="UTF-8"?> xsi:schemaLocation="http://www.springframework.org/schema/beans <bean id="calculationBean" class="com.neveropen.CalculationImpl"></bean> <bean name="/Calculation.http" class="org.springframework.remoting.caucho.HessianServiceExporter"> <property name="service" ref="calculationBean"></property> <property name="serviceInterface" value="com.neveropen.Calculation"></property> </bean></beans> |
E. File: client-beans.xml
The bean for HessianProxyFactoryBean is defined in this XML file. This class requires two attributes to be defined.
- serviceUrl
- serviceInterface
F. File: Client.java
This class obtains a Calculation object and runs the cube function.
Java
package com.neveropen;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext; public class Client { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("client-beans.xml"); Calculation calculation = (Calculation)context.getBean("calculationBean"); System.out.println(calculation.cube(4)); }} |
Output:
Note: In order to generate the above output,
- Start and deploy the project, assuming that the server is listening on port 8888. Change the serviceURL in client-beans.xml if the port number is changed.
- The Client.java file should then be compiled and run.
