The Http Cluster Servlet is included with your WebLogic Server installation. In order for it to function however, you will have to deploy it on the proxy server you just created and make it the default web application for that server. Follow the steps below; note that we have used the names that we selected above for our domain, if you used different names, substitute those for the myProxyDomain:

1. Create a directory. Let's call it, 'defaultProxyApp'. Within this directory create another called WEB-INF.

2. Create a file called web.xml in this WEB-INF directory and open it with an editor.

3. The following is an example of how the web.xml file may look. You can just paste the text below into the file, however, you will want to modify the values in blue to match the server names and ports of the managed servers you specified when you created your cluster. Although that will be all you need to modify, what follows is an explanation of what this file does.

   The first stanza of this file maps to a DTD which is used by WebLogic to make sure you have used the proper syntax. The second stanza specifies the location of the actual servlet class you will be using. This file is located in the weblogic.jar in your WL_HOME /server/lib directory. There is no need to give the full location in the web.xml file because the weblogic.jar is put automatically in the CLASSPATH when you start WebLogic. The following stanza gives the server name and port number of the cluster members. If you were using SSL, each server would have a second port (ie ms1:7011:7012|ms2:7021:7022). The next two stanzas turn on debugging info which can be helpful in diagnosing errors. The last stanzas tell the HTTP Cluster Servlet which URLs to forward to the cluster. In this case, it will forward any requests ending in: '/', 'htm', 'html', or 'jsp'.

   <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.
   //DTD Web Application 2.2//EN" 
   "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd"> 
   
   <web-app>
   
   <servlet>    
   <servlet-name>HttpClusterServlet</servlet-name>         
   <servlet-class>weblogic.servlet.internal.HttpClusterServlet</servlet-class> 
      
      <init-param>        
       <param-name>defaultServers</param-name>        
       <param-value>ms1:7011|ms2:7021</param-value>     
       </init-param>
       
       <init-param>
         <param-name>verbose</param-name> 
         <param-value>true</param-value> 
     </init-param>
     
       <init-param>        
       <param-name>DebugConfigInfo</param-name>        
       <param-value>ON</param-value>     
       </init-param>
   </servlet>
   
   <servlet-mapping>    
   <servlet-name>HttpClusterServlet</servlet-name>    
   <url-pattern>/</url-pattern>
   </servlet-mapping>
   
   <servlet-mapping>    
   <servlet-name>HttpClusterServlet</servlet-name>     
   <url-pattern>*.jsp</url-pattern> 
   </servlet-mapping>
   
   <servlet-mapping>    
   <servlet-name>HttpClusterServlet</servlet-name>     
   <url-pattern>*.htm</url-pattern> 
   </servlet-mapping>
   
   <servlet-mapping>    
   <servlet-name>HttpClusterServlet</servlet-name>     
   <url-pattern>*.html</url-pattern> 
   </servlet-mapping>
   
   </web-app>
   

4. In your Administration Console home, select 'Web Applications' under 'Your Deployed Resources.' Select 'Configure a New Web Application.' At the bottom of the screen, navigate until you find the defaultProxyApp directory you created earlier. Click on the 'Select' button next to defaultProxyApp.

5. Target the httpProxy server. Click 'Configure and Deploy.' Deployment will fail, since we haven't started the server yet, but the HTTP Proxy servlet will be deployed once you start the proxy server.

6. It is necessary that the proxy server is explicitly told that the web application we have created for the HTTP Cluster Servlet is the default Web Appplication. In the left hand pane of the Administration Console, open the Servers directory and select the httpProxy node. Go to the 'Connections' tab and then select the 'HTTP' tab. Select 'defaultProxyApp' as your Default Web Application and click 'apply.'

   At this point you have an Administration Server, Managed Servers in a cluster, and one Managed Server outside the cluster that will use the HTTP cluster servlet to proxy requests to the cluster. Now we must build the example, start our servers and install the example so that it can be deployed to the cluster.

1. Open a separate browser window in which you will run the client.

2. Run the example by using syntax like, http://ip_address_of_proxy_server:port_of_proxy_server/InMemRepClient/Session.jsp. For example:

   http://127.0.0.1:7031/InMemRepClient/Session.jsp

   Add some values. Now bring down the server that you just requested the JSP from. Refresh the browser to demonstrate session persistence.

There's More...

Troubleshooting:

http://127.0.0.1:7051/foo.jsp?__WebLogicBridgeConfig

If you are having problems try rebooting all your servers, some of hte changes you made while configuring your setup may not have been persisted. Also, use the Administration Console of your Admin Server. The console is a powerful tool to spot mistaken ip addresses, undeployed applications, and misconfigured servers.

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