java rpc

一、简介

    Hessian和Burlap是由Caucho Technology提供的基于HTTP协议的轻量级远程服务解决方案。他们都致力于借助尽可能简单那的API和通信协议来简化Web服务。
    Hession和Burlap就如同一个事物的两面，但是每一个解决方案都服务于略微不同的目的。Hession就像RMI一样，使用二进制尽心客户端和服务端的交互。但与其他二进制远程调用技术（如，RMI）不同的是，它的二进制消息可以移植到其他开发语言中（如，PHP、Python、C++、C#）。Burlap是一种基于XML的远程调用技术，这使得它可以自然而然的移植到任何能够解析XML的语言上。正因为如此，Burlap比起Hessian的二进制格式而言有更强的可读性。但，与其他基于XML的远程技术（如，SOAP、XML-RPC）不同，Burlap的消息结构尽可能的简单，不需要额外的外部定义语言（如，WSDL、IDL）。
    你可能想知道如何在Hession和Burlap之间抉择，很大程度，他们是一样的。唯一的区别在于Hession的消息似乎二进制的，在带宽上更有优势，而Burlap的消息是XML的，有更好的可读性。
    由于Hessian和Burlap都是基于HTTP协议的，他们都解决了RMI所头疼的防火墙渗透问题。但是当传递过来的RPC消息中包含序列化对象时，RMI就完胜Hessian和Burlap了。因为Hessian和Burlap都采用私有的序列化机制，如果数据模型非常复杂，那么Hessian和Burlap的序列化模型可能无法胜任。

二、Hession开发步骤

    1、编写服务接口

1 package com.cnblogs.javalouvre.service;
2 
3 public interface GreetService {
4 
5     String sayHello(String name);
6 
7 }

    2、编写服务实现类，须继承自com.caucho.hessian.server.HessianServlet

 1 package com.cnblogs.javalouvre.service;
 2 
 3 import com.caucho.hessian.server.HessianServlet;
 4 
 5 public class GreetServiceImpl extends HessianServlet implements GreetService {
 6 
 7     private static final long serialVersionUID = 1880738686281295739L;
 8 
 9     @Override
10     public String sayHello(String name) {
11         return "Hello " + name;
12     }
13 
14 }

    3、配置web.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns="http://java.sun.com/xml/ns/javaee"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
 5     version="2.5">
 6 
 7   <servlet>
 8    <servlet-name>HessianServlet</servlet-name>
 9    <servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class>
10     <init-param>
11       <param-name>home-class</param-name>
12       <param-value>com.cnblogs.javalouvre.service.GreetServiceImpl</param-value>
13     </init-param>
14     <init-param>
15       <param-name>home-api</param-name>
16       <param-value>com.cnblogs.javalouvre.service.GreetService</param-value>
17     </init-param>
18     <load-on-startup>1</load-on-startup>
19   </servlet>
20 
21   <servlet-mapping>
22     <servlet-name>HessianServlet</servlet-name>
23     <url-pattern>/GreetService</url-pattern>
24   </servlet-mapping>
25 
26   <welcome-file-list>
27     <welcome-file>index.html</welcome-file>
28     <welcome-file>index.htm</welcome-file>
29     <welcome-file>index.jsp</welcome-file>
30   </welcome-file-list>
31 
32 </web-app>

    4、测试客户端

 1 package com.cnblogs.javalouvre.client;
 2 
 3 import java.net.MalformedURLException;
 4 
 5 import com.caucho.hessian.client.HessianProxyFactory;
 6 import com.cnblogs.javalouvre.service.GreetService;
 7 
 8 public class Client {
 9 
10     public static void main(String[] args) {
11         String url = "http://10.108.1.138:8080/Hessian/GreetService";
12 
13         try {
14             GreetService service = (GreetService) (new HessianProxyFactory()).create(GreetService.class, url);
15             System.out.println(service.sayHello("Jobs"));
16         } catch (MalformedURLException e) {
17             e.printStackTrace();
18         }
19     }
20 
21 }

三、Burlap开发步骤

    1、编写服务接口(同Hessian示例的接口)
    2、编写服务实现类，须继承自com.caucho.burlap.server.BurlapServlet

 1 package com.cnblogs.javalouvre.service;
 2 
 3 import com.caucho.burlap.server.BurlapServlet;
 4 
 5 public class GreetServiceImpl extends BurlapServlet implements GreetService {
 6 
 7     @Override
 8     public String sayHello(String name) {
 9         return "Hello " + name;
10     }
11 
12 }

    3、配置web.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns="http://java.sun.com/xml/ns/javaee"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
 5     version="2.5">
 6 
 7   <servlet>
 8    <servlet-name>GreetService</servlet-name>
 9    <servlet-class>com.cnblogs.javalouvre.service.GreetServiceImpl</servlet-class>
10     <load-on-startup>1</load-on-startup>
11   </servlet>
12 
13   <servlet-mapping>
14     <servlet-name>GreetService</servlet-name>
15     <url-pattern>/GreetService</url-pattern>
16   </servlet-mapping>
17 
18   <welcome-file-list>
19     <welcome-file>index.html</welcome-file>
20     <welcome-file>index.htm</welcome-file>
21     <welcome-file>index.jsp</welcome-file>
22   </welcome-file-list>
23 
24 </web-app>

    4、测试客户端

 1 package com.cnblogs.javalouvre.client;
 2 
 3 import java.net.MalformedURLException;
 4 
 5 import com.caucho.burlap.client.BurlapProxyFactory;
 6 import com.cnblogs.javalouvre.service.GreetService;
 7 
 8 public class Client {
 9 
10     public static void main(String[] args) {
11         String url = "http://10.108.1.138:8080/Burlap/GreetService";
12 
13         try {
14             GreetService service = (GreetService) (new BurlapProxyFactory()).create(GreetService.class, url);
15             System.out.println(service.sayHello("Jobs"));
16         } catch (MalformedURLException e) {
17             e.printStackTrace();
18         }
19     }
20 
21 }