前言
        Ribbon 是提供 REST 服务的区域感知负载均衡器，它在 wowza 的前端，应该部署在专业的 REST 容器下，而不是流媒体服务器 wowza 下。

本文介绍了 Ribbon 和 wowza 的集成，Ribbon 作为 wowza 的一个插件部署在了 wowza 容器下，仅供 Ribbon 开发、部署的技术參考，现实中绝不可能出现这样的情况。由于 Wowza 毕竟不是专业提供 REST 服务的容器。关于 Ribbon 和 Wowza 真实场景的架构部署，请关注作者兴许博客。
        本文是在《让你的 wowza 服务器提供 RESTful web 服务》样例的基础上进一步进行研发。
        1. 新建 maven 项目
        參考《让你的 wowza 服务器提供 RESTful web 服务》步骤。新建的 maven 项目 defonds-server-module 例如以下：

        2. 编辑 Ribbon 配置文件
        依据你自己的集群。配置 Ribbon。比方作者 demo 用的配置文件例如以下：

# Max number of retries on the same server (excluding the first try)
sample-client.ribbon.MaxAutoRetries=1# Max number of next servers to retry (excluding the first server)
sample-client.ribbon.MaxAutoRetriesNextServer=1# Whether all operations can be retried for this client
sample-client.ribbon.OkToRetryOnAllOperations=true# Interval to refresh the server list from the source
sample-client.ribbon.ServerListRefreshInterval=2000# Connect timeout used by Apache HttpClient
sample-client.ribbon.ConnectTimeout=3000# Read timeout used by Apache HttpClient
sample-client.ribbon.ReadTimeout=3000# Initial list of servers, can be changed via Archaius dynamic property at runtime
sample-client.ribbon.listOfServers=www.baidu.com:80,www.163.com:80,www.csdn.net:80

然后把这个文件放在你的 classpath 下。
        3. 编写 LB 调用类

package com.defonds.wms.module.server;import java.io.IOException;
import java.io.OutputStream;
import java.net.URI;
import java.net.URISyntaxException;import com.netflix.client.ClientException;
import com.netflix.client.ClientFactory;
import com.netflix.client.http.HttpRequest;
import com.netflix.client.http.HttpResponse;
import com.netflix.config.ConfigurationManager;
import com.netflix.niws.client.http.RestClient;
import com.wowza.wms.http.HTTProvider2Base;
import com.wowza.wms.http.IHTTPRequest;
import com.wowza.wms.http.IHTTPResponse;
import com.wowza.wms.logging.WMSLogger;
import com.wowza.wms.logging.WMSLoggerFactory;
import com.wowza.wms.vhost.IVHost;public class RibbonLBRestService extends HTTProvider2Base {private static final WMSLogger logger = WMSLoggerFactory.getInstance().getLoggerObj(RibbonLBRestService.class.getName());public static RestClient restClient = null;static {try {// Load the properties file using Archaius ConfigurationManagerConfigurationManager.loadPropertiesFromResources("sample-client.properties"); // Use ClientFactory to create client and the load balancerRibbonLBRestService.restClient = (RestClient) ClientFactory.getNamedClient("sample-client");  } catch (IOException e) {logger.error(e.getMessage(), e);}  }@Overridepublic void onHTTPRequest(IVHost arg0, IHTTPRequest request, IHTTPResponse response) {String jsonObject = null;response.setHeader("Content-Type", "application/json");try {String serverURI = RibbonLBRestService.getURI();response.setResponseCode(200);jsonObject = "{\"server_uri\":\"" + serverURI + "\"}";} catch (ClientException e2) {response.setResponseCode(400);jsonObject = "{\"error_code\":\"40039\"}";logger.error(e2.getMessage(), e2);} catch (URISyntaxException e3) {response.setResponseCode(400);jsonObject = "{\"error_code\":\"40023\"}";logger.error(e3.getMessage(), e3);} finally {// Get the printwriter object from response to write the required json object to the output stream      OutputStream out = response.getOutputStream();try {out.write(jsonObject.getBytes());out.flush();} catch (IOException e) {logger.error(e.getMessage(), e);}}}public synchronized static String getURI() throws ClientException, URISyntaxException {// Build the http request using the builder// Note that we only supply the path part (“/”) of the URI// The complete URI will be computed by the client once the server is chosen by the load balancerHttpRequest ribbonRequest = HttpRequest.newBuilder().uri(new URI("/")).build(); HttpResponse ribbonResponse;// Call client.executeWithLoadBalancer() API, not the execute() APIribbonResponse = RibbonLBRestService.restClient.executeWithLoadBalancer(ribbonRequest); return ribbonResponse.getRequestedURI().toString();}public synchronized static void changeServersPoolDynamically(String serverList) throws ClientException {// Dynamically change the server pool from the configurationConfigurationManager.getConfigInstance().setProperty("sample-client.ribbon.listOfServers", serverList); logger.debug("changing servers ...");try {// Wait until server list is refreshed (2 seconds refresh interval defined in properties file)Thread.sleep(3000); } catch (InterruptedException e) {logger.error(e.getMessage(), e);} }}

这个类将会给 ribbonLB 的 REST 请求返回一台服务器地址。假设请求失败，返回对应的错误码。

这个类还提供了一个公开方法，用于动态调整负载均衡节点。
        4. 编写动态改动负载均衡节点接口

package com.defonds.wms.module.server;import java.io.IOException;
import java.io.OutputStream;import com.netflix.client.ClientException;
import com.wowza.wms.http.HTTProvider2Base;
import com.wowza.wms.http.IHTTPRequest;
import com.wowza.wms.http.IHTTPResponse;
import com.wowza.wms.logging.WMSLogger;
import com.wowza.wms.logging.WMSLoggerFactory;
import com.wowza.wms.vhost.IVHost;public class RibbonChangeInstanceService extends HTTProvider2Base {private static final WMSLogger logger = WMSLoggerFactory.getInstance().getLoggerObj(RibbonChangeInstanceService.class.getName());@Overridepublic void onHTTPRequest(IVHost arg0, IHTTPRequest request, IHTTPResponse response) {String serverList = request.getParameter("server_list");// TODO Authorization// TODO serverList str checkString jsonObject = null;response.setHeader("Content-Type", "application/json");try {RibbonLBRestService.changeServersPoolDynamically(serverList);response.setResponseCode(200);jsonObject = "{\"error_code\":\"0\"}"; // server list is changed successfully} catch (ClientException e2) {response.setResponseCode(400);jsonObject = "{\"error_code\":\"40039\"}";logger.error(e2.getMessage(), e2);} finally {// Get the printwriter object from response to write the required json object to the output stream      OutputStream out = response.getOutputStream();try {out.write(jsonObject.getBytes());out.flush();} catch (IOException e) {logger.error(e.getMessage(), e);}}} }

这个类提供了一个用于动态改动负载均衡节点池的接口。假设改动成功返回错误码为 0，否则为其它值。

5. 编辑 maven 依赖

编辑项目 pom.xml。将上边依赖到的包导入：

     <!-- ribbon --><dependency><groupId>com.netflix.ribbon</groupId><artifactId>ribbon-core</artifactId><version>0.3.12</version></dependency><dependency><groupId>com.netflix.ribbon</groupId><artifactId>ribbon-httpclient</artifactId><version>0.3.12</version></dependency>

6. 编辑 VHost.xml
        编辑 %wowza%/conf/VHost.xml，把上边写的两个 HTTPProvider 加入进去：

                    <HTTPProvider><BaseClass>com.defonds.wms.module.server.RibbonLBRestService</BaseClass><RequestFilters>ribbonLB*</RequestFilters><AuthenticationMethod>none</AuthenticationMethod></HTTPProvider><HTTPProvider><BaseClass>com.defonds.wms.module.server.RibbonChangeInstanceService</BaseClass><RequestFilters>ribbonChange*</RequestFilters><AuthenticationMethod>none</AuthenticationMethod></HTTPProvider>

7. 项目又一次打包部署
        命令行切换到你的 defonds-server-module 项目文件夹下，运行
mvn package
        8. 訪问接口
        debug 启动 defonds-server-module，然后在浏览器訪问 http://localhost:1935/ribbonLB，以向 Ribbon 要一个服务器地址，返回结果例如以下：
{"server_uri":"http://www.csdn.net:80/"}
        返回的是服务器 URL 是 http://www.csdn.net:80/。然后在浏览器訪问 http://localhost:1935/ribbonChange?server_list=www.qq.com:80,www.126.com:80。以动态调整负载均衡节点。返回结果例如以下：
{"error_code":"0"}
        这个返回码说明已经调整成功。我们能够继续訪问 http://localhost:1935/ribbonLB 验证一下，返回结果是：
{"server_uri":"http://www.qq.com:80/"}
        没错，确实成功了。

注意
        以上 Ribbon 动态调整的负载均衡节点是内存里的配置。服务器下的 sample-client.properties 配置的节点依然是：

sample-client.ribbon.listOfServers=www.baidu.com:80,www.163.com:80,www.csdn.net:80

这样 REST 服务重新启动后。读取的负载均衡节点依然是改动前的。假设你想在 REST 服务器断电重新启动后读取改动后的。最好把 Ribbon 属性在分布式缓存服务器中进行存放和读取，比方 Redis。

另：本文演示样例代码已上传 CSDN 资源。下载地址：http://download.csdn.net/detail/defonds/7526359。