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Dubbo基于Hessian實現(xiàn)了自己Hessian協(xié)議,可以直接通過配置的Dubbo內(nèi)置的其他協(xié)議,在服務(wù)消費方進行遠程調(diào)用,也就是說,服務(wù)調(diào)用方需要使用Java語言來基于Dubbo調(diào)用提供方服務(wù),限制了服務(wù)調(diào)用方。同時,使用Dubbo的Hessian協(xié)議實現(xiàn)提供方服務(wù),而調(diào)用方可以使用標準的Hessian接口來調(diào)用,原生的Hessian協(xié)議已經(jīng)支持多語言客戶端調(diào)用,支持語言如下所示:
下面,我們的思路是,先基于Dubbo封裝的Hessian協(xié)議,實現(xiàn)提供方服務(wù)和消費方調(diào)用服務(wù),雙方必須都使用Dubbo來開發(fā);然后,基于Dubbo封裝的Hessian協(xié)議實現(xiàn)提供方服務(wù),然后服務(wù)消費方使用標準的Hessian接口來進行遠程調(diào)用,分別使用Java和Python語言來實現(xiàn)。而且,我們實現(xiàn)的提供方服務(wù)通過Tomcat發(fā)布到服務(wù)注冊中心。
首先,使用Java語言定義一個搜索服務(wù)的接口,代碼如下所示:
1 | package org.shirdrn.platform.dubbo.service.rpc.api; |
3 | public interface SolrSearchService { |
4 | String search(String collection, String q, String type, int start, int rows); |
上面接口提供了搜索遠程調(diào)用功能。
基于Dubbo的Hessian協(xié)議實現(xiàn)提供方服務(wù)
提供方實現(xiàn)基于Dubbo封裝的Hessian協(xié)議,實現(xiàn)接口SolrSearchService,實現(xiàn)代碼如下所示:
01 | package org.shirdrn.platform.dubbo.service.rpc.server; |
03 | import java.io.IOException; |
04 | import java.util.HashMap; |
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; |
13 | public class SolrSearchServer implements SolrSearchService { |
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); |
20 | handlers.put("xml", new FormatHandler() { |
21 | public String format() { |
25 | handlers.put("json", new FormatHandler() { |
26 | public String format() { |
32 | public SolrSearchServer() { |
34 | postClient = QueryPostClient.newIndexingClient(null); |
37 | public void setBaseUrl(String baseUrl) { |
38 | this.baseUrl = baseUrl; |
41 | public String search(String collection, String q, String type, int start, int rows) { |
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()); |
50 | interface FormatHandler { |
因為考慮到后面要使用標準Hessian接口來調(diào)用,這里接口方法參數(shù)全部使用內(nèi)置標準類型。然后,我們使用Dubbo的配置文件進行配置,文件search-provider.xml的內(nèi)容如下所示:
01 | <?xml version="1.0" encoding="UTF-8"?> |
08 | <dubbo:application name="search-provider" /> |
11 | <dubbo:protocol name="hessian" port="8080" server="servlet" /> |
12 | <bean id="searchService" |
13 | class="org.shirdrn.platform.dubbo.service.rpc.server.SolrSearchServer"> |
17 | interface="org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService" |
18 | ref="searchService" path="http_dubbo/search" /> |
因為使用Tomcat發(fā)布提供方服務(wù),所以我們需要實現(xiàn)Spring的org.springframework.web.context.ContextLoader來初始化應(yīng)用上下文(基于Spring的IoC容器來管理服務(wù)對象)。實現(xiàn)類SearchContextLoader代碼如下所示:
01 | package org.shirdrn.platform.dubbo.context; |
03 | import javax.servlet.ServletContextEvent; |
04 | import javax.servlet.ServletContextListener; |
06 | import org.shirdrn.platform.dubbo.service.rpc.server.SolrSearchServer; |
07 | import org.springframework.context.support.ClassPathXmlApplicationContext; |
08 | import org.springframework.web.context.ContextLoader; |
10 | public class SearchContextLoader extends ContextLoader implements ServletContextListener { |
13 | public void contextDestroyed(ServletContextEvent arg0) { |
14 | // TODO Auto-generated method stub |
19 | public void contextInitialized(ServletContextEvent arg0) { |
20 | String config = arg0.getServletContext().getInitParameter("contextConfigLocation"); |
21 | ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(config); |
最后,配置Web應(yīng)用部署描述符文件,web.xml內(nèi)容如下所示:
01 | <?xml version="1.0" encoding="UTF-8"?> |
02 | <web-app id="WebApp_ID" version="2.4" |
05 | <display-name>http_dubbo</display-name> |
08 | <listener-class>org.shirdrn.platform.dubbo.context.SearchContextLoader</listener-class> |
11 | <param-name>contextConfigLocation</param-name> |
12 | <param-value>classpath:search-provider.xml</param-value> |
16 | <servlet-name>search</servlet-name> |
17 | <servlet-class>com.alibaba.dubbo.remoting.http.servlet.DispatcherServlet</servlet-class> |
19 | <param-name>home-class</param-name> |
20 | <param-value>org.shirdrn.platform.dubbo.service.rpc.server.SolrSearchServer</param-value> |
23 | <param-name>home-api</param-name> |
24 | <param-value>org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService</param-value> |
26 | <load-on-startup>1</load-on-startup> |
29 | <servlet-name>search</servlet-name> |
30 | <url-pattern>/search</url-pattern> |
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> |
啟動Tomcat以后,就可以將提供方服務(wù)發(fā)布到服務(wù)注冊中心,這里服務(wù)注冊中心我們使用的是ZooKeeper集群,可以參考上面Dubbo配置文件search-provider.xml的配置內(nèi)容。
下面,我們通過兩種方式來調(diào)用已經(jīng)注冊到服務(wù)注冊中心的服務(wù)。
- 基于Dubbo的Hessian協(xié)議遠程調(diào)用
服務(wù)消費方,通過Dubbo配置文件來指定注冊到注冊中心的服務(wù),配置文件search-consumer.xml的內(nèi)容,如下所示:
01 | <?xml version="1.0" encoding="UTF-8"?> |
08 | <dubbo:application name="search-consumer" /> |
11 | <dubbo:reference id="searchService" |
12 | interface="org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService" /> |
然后,使用Java實現(xiàn)遠程調(diào)用,實現(xiàn)代碼如下所示:
01 | package org.shirdrn.platform.dubbo.service.rpc.client; |
03 | import java.util.concurrent.Callable; |
04 | import java.util.concurrent.Future; |
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; |
11 | import com.alibaba.dubbo.rpc.RpcContext; |
13 | public class SearchConsumer { |
15 | private final String collection; |
16 | private AbstractXmlApplicationContext context; |
17 | private SolrSearchService searchService; |
19 | public SearchConsumer(String collection, Callable<AbstractXmlApplicationContext> call) { |
21 | this.collection = collection; |
23 | context = call.call(); |
25 | searchService = (SolrSearchService) context.getBean("searchService"); |
26 | } catch (BeansException e) { |
28 | } catch (Exception e) { |
33 | public Future<String> asyncCall(final String q, final String type, final int start, 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); |
42 | public String syncCall(final String q, final String type, final int start, final int rows) { |
43 | return search(q, type, start, rows); |
46 | private String search(final String q, final String type, final int start, final int rows) { |
47 | return searchService.search(collection, q, type, start, rows); |
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, new Callable<AbstractXmlApplicationContext>() { |
55 | public AbstractXmlApplicationContext call() throws Exception { |
56 | final AbstractXmlApplicationContext context = new ClassPathXmlApplicationContext(config); |
61 | String q = "q=上海&fl=*&fq=building_type:1"; |
65 | for (int k = 0; k < 10; k++) { |
66 | for (int i = 0; i < 10; i++) { |
73 | String result = consumer.syncCall(q, type, start, rows); |
74 | System.out.println(result); |
75 | // Future<String> future = consumer.asyncCall(q, type, start, |
77 | // System.out.println(future.get()); |
執(zhí)行該調(diào)用實現(xiàn),可以遠程調(diào)用提供方發(fā)布的服務(wù)。
這種方式限制了服務(wù)調(diào)用方也必須使用Dubbo來開發(fā)調(diào)用的代碼,也就是限制了編程的語言,而無論是對于內(nèi)部還是外部,各個團隊之間必然存在語言的多樣性,如果限制了編程語言,那么開發(fā)的服務(wù)也只能在內(nèi)部使用。
- 基于標準Hessian協(xié)議接口的遠程調(diào)用
下面,使用標準Hessian接口來實現(xiàn)遠程調(diào)用,這時就不需要關(guān)心服務(wù)提供方的所使用的開發(fā)語言,因為最終是通過HTTP的方式來訪問。我們需要下載Hessian對應(yīng)語言的調(diào)用實現(xiàn)庫,才能更方便地編程。
使用Java語言實現(xiàn)遠程調(diào)用
使用Java語言實現(xiàn),代碼如下所示:
01 | package org.shirdrn.rpc.hessian; |
03 | import org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService; |
05 | import com.caucho.hessian.client.HessianProxyFactory; |
07 | public class HessianConsumer { |
09 | public static void main(String[] args) throws Throwable { |
11 | String serviceUrl = "; |
12 | HessianProxyFactory factory = new HessianProxyFactory(); |
14 | SolrSearchService searchService = (SolrSearchService) factory.create(SolrSearchService.class, serviceUrl); |
16 | String q = "q=上海&fl=*&fq=building_type:1"; |
17 | String collection = "tinycollection"; |
21 | String result = searchService.search(collection, q, type, start, rows); |
22 | System.out.println(result); |
我們只需要知道提供服務(wù)暴露的URL和服務(wù)接口即可,這里URL為http://10.95.3.74:8080/http_dubbo/search,接口為org.shirdrn.platform.dubbo.service.rpc.api.SolrSearchService。運行上面程序,可以調(diào)用提供方發(fā)布的服務(wù)。
使用Python語言實現(xiàn)遠程調(diào)用
使用Python客戶端來進行遠程調(diào)用,我們可以從https://github.com/bgilmore/mustaine下載,然后安裝Hessian的代理客戶端Python實現(xiàn)庫:
3 | sudo python setup.py install |
然后就可以使用了,使用Python進行遠程調(diào)用的實現(xiàn)代碼如下所示:
04 | from mustaine.client import HessianProxy |
07 | q = 'q=*:*&fl=*&fq=building_type:1' |
11 | collection = 'tinycollection' |
13 | if __name__ == '__main__': |
14 | proxy = HessianProxy(serviceUrl) |
15 | result = proxy.search(collection, q, resType, start, rows) |
運行上面程序,就可以看到遠程調(diào)用的結(jié)果。
參考鏈接
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