基于Dubbo的Hessian协议实现远程调用

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基于Dubbo的Hessian协议实现远程调用

shiyanjuncn 2016-04-14 10:04:57 浏览3989
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Dubbo基于Hessian实现了自己Hessian协议,可以直接通过配置的Dubbo内置的其他协议,在服务消费方进行远程调用,也就是说,服务调用方需要使用Java语言来基于Dubbo调用提供方服务,限制了服务调用方。同时,使用Dubbo的Hessian协议实现提供方服务,而调用方可以使用标准的Hessian接口来调用,原生的Hessian协议已经支持多语言客户端调用,支持语言如下所示:

下面,我们的思路是,先基于Dubbo封装的Hessian协议,实现提供方服务和消费方调用服务,双方必须都使用Dubbo来开发;然后,基于Dubbo封装的Hessian协议实现提供方服务,然后服务消费方使用标准的Hessian接口来进行远程调用,分别使用Java和Python语言来实现。而且,我们实现的提供方服务通过Tomcat发布到服务注册中心。
首先,使用Java语言定义一个搜索服务的接口,代码如下所示:

1 package org.shirdrn.platform.dubbo.service.rpc.api;
2
3 public interface SolrSearchService {
4 String search(String collection, String q, String type, int start, int rows);
5 }

上面接口提供了搜索远程调用功能。

基于Dubbo的Hessian协议实现提供方服务

提供方实现基于Dubbo封装的Hessian协议,实现接口SolrSearchService,实现代码如下所示:

01 package org.shirdrn.platform.dubbo.service.rpc.server;
02
03 import java.io.IOException;
04 import java.util.HashMap;
05 import java.util.Map;
06
07 import org.apache.commons.logging.Log;
08 import org.apache.commons.logging.LogFactory;
09 import org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService;
10 import org.shirdrn.platform.dubbo.service.rpc.utils.QueryPostClient;
11 import org.springframework.context.support.ClassPathXmlApplicationContext;
12
13 public class SolrSearchServer implements SolrSearchService {
14
15 private static final Log LOG = LogFactory.getLog(SolrSearchServer.class);
16 private String baseUrl;
17 private final QueryPostClient postClient;
18 private static final Map<String, FormatHandler> handlers = new HashMap<String, FormatHandler>(0);
19 static {
20 handlers.put("xml", new FormatHandler() {
21 public String format() {
22 return "&wt=xml";
23 }
24 });
25 handlers.put("json", new FormatHandler() {
26 public String format() {
27 return "&wt=json";
28 }
29 });
30 }
31
32 public SolrSearchServer() {
33 super();
34 postClient = QueryPostClient.newIndexingClient(null);
35 }
36
37 public void setBaseUrl(String baseUrl) {
38 this.baseUrl = baseUrl;
39 }
40
41 public String search(String collection, String q, String type, int start, introws) {
42 StringBuffer url = new StringBuffer();
43 url.append(baseUrl).append(collection).append("/select?").append(q);
44 url.append("&start=").append(start).append("&rows=").append(rows);
45 url.append(handlers.get(type.toLowerCase()).format());
46 LOG.info("[REQ] " + url.toString());
47 return postClient.request(url.toString());
48 }
49
50 interface FormatHandler {
51 String format();
52 }
53 }

因为考虑到后面要使用标准Hessian接口来调用,这里接口方法参数全部使用内置标准类型。然后,我们使用Dubbo的配置文件进行配置,文件search-provider.xml的内容如下所示:

01 <?xml version="1.0" encoding="UTF-8"?>
02
03 <beans xmlns="http://www.springframework.org/schema/beans"
04 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
05 xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsd
06 http://code.alibabatech.com/schema/dubbohttp://code.alibabatech.com/schema/dubbo/dubbo.xsd">
07
08 <dubbo:application name="search-provider" />
09 <dubbo:registry
10 address="zookeeper://slave1:2188?backup=slave3:2188,slave4:2188" />
11 <dubbo:protocol name="hessian" port="8080" server="servlet" />
12 <bean id="searchService"
13 class="org.shirdrn.platform.dubbo.service.rpc.server.SolrSearchServer">
14 <property name="baseUrl" value="http://nginx-lbserver/solr-cloud/" />
15 </bean>
16 <dubbo:service
17 interface="org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService"
18 ref="searchService" path="http_dubbo/search" />
19
20 </beans>

因为使用Tomcat发布提供方服务,所以我们需要实现Spring的org.springframework.web.context.ContextLoader来初始化应用上下文(基于Spring的IoC容器来管理服务对象)。实现类SearchContextLoader代码如下所示:

01 package org.shirdrn.platform.dubbo.context;
02
03 import javax.servlet.ServletContextEvent;
04 import javax.servlet.ServletContextListener;
05
06 import org.shirdrn.platform.dubbo.service.rpc.server.SolrSearchServer;
07 import org.springframework.context.support.ClassPathXmlApplicationContext;
08 import org.springframework.web.context.ContextLoader;
09
10 public class SearchContextLoader extends ContextLoader implementsServletContextListener {
11
12 @Override
13 public void contextDestroyed(ServletContextEvent arg0) {
14 // TODO Auto-generated method stub
15
16 }
17
18 @Override
19 public void contextInitialized(ServletContextEvent arg0) {
20 String config = arg0.getServletContext().getInitParameter("contextConfigLocation");
21 ClassPathXmlApplicationContext context = newClassPathXmlApplicationContext(config);
22 context.start();
23 }
24
25 }

最后,配置Web应用部署描述符文件,web.xml内容如下所示:

01 <?xml version="1.0" encoding="UTF-8"?>
02 <web-app id="WebApp_ID" version="2.4"
03 xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
04 xsi:schemaLocation="http://java.sun.com/xml/ns/j2eehttp://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
05 <display-name>http_dubbo</display-name>
06
07 <listener>
08 <listener-class>org.shirdrn.platform.dubbo.context.SearchContextLoader</listener-class>
09 </listener>
10 <context-param>
11 <param-name>contextConfigLocation</param-name>
12 <param-value>classpath:search-provider.xml</param-value>
13 </context-param>
14
15 <servlet>
16 <servlet-name>search</servlet-name>
17 <servlet-class>com.alibaba.dubbo.remoting.http.servlet.DispatcherServlet</servlet-class>
18 <init-param>
19 <param-name>home-class</param-name>
20 <param-value>org.shirdrn.platform.dubbo.service.rpc.server.SolrSearchServer</param-value>
21 </init-param>
22 <init-param>
23 <param-name>home-api</param-name>
24 <param-value>org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService</param-value>
25 </init-param>
26 <load-on-startup>1</load-on-startup>
27 </servlet>
28 <servlet-mapping>
29 <servlet-name>search</servlet-name>
30 <url-pattern>/search</url-pattern>
31 </servlet-mapping>
32
33 <welcome-file-list>
34 <welcome-file>index.html</welcome-file>
35 <welcome-file>index.htm</welcome-file>
36 <welcome-file>index.jsp</welcome-file>
37 <welcome-file>default.html</welcome-file>
38 <welcome-file>default.htm</welcome-file>
39 <welcome-file>default.jsp</welcome-file>
40 </welcome-file-list>
41 </web-app>

启动Tomcat以后,就可以将提供方服务发布到服务注册中心,这里服务注册中心我们使用的是ZooKeeper集群,可以参考上面Dubbo配置文件search-provider.xml的配置内容。

下面,我们通过两种方式来调用已经注册到服务注册中心的服务。

  • 基于Dubbo的Hessian协议远程调用

服务消费方,通过Dubbo配置文件来指定注册到注册中心的服务,配置文件search-consumer.xml的内容,如下所示:

01 <?xml version="1.0" encoding="UTF-8"?>
02
03 <beans xmlns="http://www.springframework.org/schema/beans"
04 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
05 xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsd
06 http://code.alibabatech.com/schema/dubbohttp://code.alibabatech.com/schema/dubbo/dubbo.xsd">
07
08 <dubbo:application name="search-consumer" />
09 <dubbo:registry
10 address="zookeeper://slave1:2188?backup=slave3:2188,slave4:2188" />
11 <dubbo:reference id="searchService"
12 interface="org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService" />
13
14 </beans>

然后,使用Java实现远程调用,实现代码如下所示:

01 package org.shirdrn.platform.dubbo.service.rpc.client;
02
03 import java.util.concurrent.Callable;
04 import java.util.concurrent.Future;
05
06 import org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService;
07 import org.springframework.beans.BeansException;
08 import org.springframework.context.support.AbstractXmlApplicationContext;
09 import org.springframework.context.support.ClassPathXmlApplicationContext;
10
11 import com.alibaba.dubbo.rpc.RpcContext;
12
13 public class SearchConsumer {
14
15 private final String collection;
16 private AbstractXmlApplicationContext context;
17 private SolrSearchService searchService;
18
19 public SearchConsumer(String collection, Callable<AbstractXmlApplicationContext> call) {
20 super();
21 this.collection = collection;
22 try {
23 context = call.call();
24 context.start();
25 searchService = (SolrSearchService) context.getBean("searchService");
26 } catch (BeansException e) {
27 e.printStackTrace();
28 } catch (Exception e) {
29 e.printStackTrace();
30 }
31 }
32
33 public Future<String> asyncCall(final String q, final String type, final intstart, final int rows) {
34 Future<String> future = RpcContext.getContext().asyncCall(new Callable<String>() {
35 public String call() throws Exception {
36 return search(q, type, start, rows);
37 }
38 });
39 return future;
40 }
41
42 public String syncCall(final String q, final String type, final int start, finalint rows) {
43 return search(q, type, start, rows);
44 }
45
46 private String search(final String q, final String type, final int start, finalint rows) {
47 return searchService.search(collection, q, type, start, rows);
48 }
49
50 public static void main(String[] args) throws Exception {
51 final String collection = "tinycollection";
52 final String beanXML = "search-consumer.xml";
53 final String config = SearchConsumer.class.getPackage().getName().replace('.','/') + "/" + beanXML;
54 SearchConsumer consumer = new SearchConsumer(collection, newCallable<AbstractXmlApplicationContext>() {
55 public AbstractXmlApplicationContext call() throws Exception {
56 final AbstractXmlApplicationContext context = newClassPathXmlApplicationContext(config);
57 return context;
58 }
59 });
60
61 String q = "q=上海&fl=*&fq=building_type:1";
62 int start = 0;
63 int rows = 10;
64 String type = "xml";
65 for (int k = 0; k < 10; k++) {
66 for (int i = 0; i < 10; i++) {
67 start = 1 * 10 * i;
68 if (i % 2 == 0) {
69 type = "xml";
70 } else {
71 type = "json";
72 }
73 String result = consumer.syncCall(q, type, start, rows);
74 System.out.println(result);
75 // Future<String> future = consumer.asyncCall(q, type, start,
76 // rows);
77 // System.out.println(future.get());
78 }
79 }
80 }
81
82 }

执行该调用实现,可以远程调用提供方发布的服务。
这种方式限制了服务调用方也必须使用Dubbo来开发调用的代码,也就是限制了编程的语言,而无论是对于内部还是外部,各个团队之间必然存在语言的多样性,如果限制了编程语言,那么开发的服务也只能在内部使用。

  • 基于标准Hessian协议接口的远程调用

下面,使用标准Hessian接口来实现远程调用,这时就不需要关心服务提供方的所使用的开发语言,因为最终是通过HTTP的方式来访问。我们需要下载Hessian对应语言的调用实现库,才能更方便地编程。

使用Java语言实现远程调用
使用Java语言实现,代码如下所示:

01 package org.shirdrn.rpc.hessian;
02
03 import org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService;
04
05 import com.caucho.hessian.client.HessianProxyFactory;
06
07 public class HessianConsumer {
08
09 public static void main(String[] args) throws Throwable {
10
11 String serviceUrl = "http://10.95.3.74:8080/http_dubbo/search";
12 HessianProxyFactory factory = new HessianProxyFactory();
13
14 SolrSearchService searchService = (SolrSearchService) factory.create(SolrSearchService.class, serviceUrl);
15
16 String q = "q=上海&fl=*&fq=building_type:1";
17 String collection = "tinycollection";
18 int start = 0;
19 int rows = 10;
20 String type = "xml";
21 String result = searchService.search(collection, q, type, start, rows);
22 System.out.println(result);
23 }
24 }

我们只需要知道提供服务暴露的URL和服务接口即可,这里URL为http://10.95.3.74:8080/http_dubbo/search,接口为org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService。运行上面程序,可以调用提供方发布的服务。

使用Python语言实现远程调用
使用Python客户端来进行远程调用,我们可以从https://github.com/bgilmore/mustaine下载,然后安装Hessian的代理客户端Python实现库:

1 git clone https://github.com/bgilmore/mustaine.git
2 cd mustaine
3 sudo python setup.py install

然后就可以使用了,使用Python进行远程调用的实现代码如下所示:

01 #!/usr/bin/python
02
03 # coding=utf-8
04 from mustaine.client import HessianProxy
05
06 serviceUrl = 'http://10.95.3.74:8080/http_dubbo/search'
07 q = 'q=*:*&fl=*&fq=building_type:1'
08 start = 0
09 rows = 10
10 resType = 'xml'
11 collection = 'tinycollection'
12
13 if __name__ == '__main__':
14 proxy = HessianProxy(serviceUrl)
15 result = proxy.search(collection, q, resType, start, rows)
16 print result

运行上面程序,就可以看到远程调用的结果。

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