We have seen how to create clusters in standalone, domain with multicast and unicast protocols also which have been listed below. However in this article we would be seeing how to use mod_cluster with our created clusters in both standalone and domain mode.

Following are the list of article we have created till now for creating a cluster in JBoss AS 7.1.1 Final till now

  1. How to create cluster in JBoss AS 7.1 in standalone mode?
  2. How to create cluster in JBoss AS 7.1 in domain mode?
  3. Creating TCP cluster in JBoss AS 7.1 in standalone mode?

Again we would be using JBoss AS 7.1.1.Final for this article as well so that we are all on the same page, as few things have been change from JBoss AS 7.0 to JBoss AS 7.1.

Changes taken place:

  1. AJP connector is enabled by default in standalone-ha.xml , standalone-full-ha.xml and domain.xml for ha and full-ha profile.
  2. Instead of JVMRoute, now we have to use instance-id

Using mod_cluster with JBoss AS 7.1 cluster

For this we would have to modify from both side Apache as well as JBoss AS7 side, hence lets see the configuration one at a time

Apache side configuration

Lets see what all configuration has to be made from Apache side

  1. You can configure mod_cluster from the below article, just follow the “Apache side configuration” part only
  2. How to configure mod_cluster with JBoss ?

  3. In the above article you can just add the IP_ADDRESS of the box on which Apache is running which is in the Step-3 something as shown below
  4. ############### mod_cluster Setting - STARTED ###############
    LoadModule slotmem_module modules/mod_slotmem.so
    LoadModule manager_module modules/mod_manager.so
    LoadModule proxy_cluster_module modules/mod_proxy_cluster.so
    LoadModule advertise_module modules/mod_advertise.so
    
    Listen 1.1.1.1:80
    
    <VirtualHost 1.1.1.1:80>
    	<Directory />
    		Order deny,allow
    		Allow from all
    	</Directory>
    	<Location /mod_cluster-manager>
    		SetHandler mod_cluster-manager
    		Order deny,allow
    		Allow from all
    	</Location>
              KeepAliveTimeout 60
              ManagerBalancerName mycluster
              ServerAdvertise On
    </VirtualHost>
    ############### mod_cluster Setting - ENDED ###############
    

JBoss side configuration

Now we would see what all changes we have to be done from JBoss end in standalone and domain files

Standalone

  1. First you would have to follow all the steps given in the link – How to create cluster in JBoss AS 7.1 in standalone mode? and then make the below changes in all the standalone servers.
  2. Give a unique name in the server element, as shown below .
  3. standalone-node1

    <server name="standalone-node1" xmlns="urn:jboss:domain:1.2">
    

    standalone-node2

    <server name="standalone-node2" xmlns="urn:jboss:domain:1.2">
    
  4. As told earlier you would have to add the instance-id attribute in web subsystem as shown below in both the standalone nodes.
  5.         <subsystem xmlns="urn:jboss:domain:web:1.1" default-virtual-server="default-host" instance-id="${jboss.node.name}" native="false">
                <connector name="http" protocol="HTTP/1.1" scheme="http" socket-binding="http"/>
                <connector name="ajp" protocol="AJP/1.3" scheme="http" socket-binding="ajp"/>
                .
                .
                .
            </subsystem>
    
  6. Last you just have to add the proxy-list in the attribute in mod-cluster-config of modcluster subsystem, which would be having IP Address and Port on which your Apache server is running so that JBoss server can communicate with it, as shown below in both the standalone nodes.
  7.         <subsystem xmlns="urn:jboss:domain:modcluster:1.0">
                <mod-cluster-config advertise-socket="modcluster" proxy-list="1.1.1.1:80">
                .
                .
                .
                </mod-cluster-config>
            </subsystem>
    

If everything is configured properly you can hit the URL = http://1.1.1.1/mod_cluster-manager which would show similar below screen. Below image is showing when cluster is been made in on the same box using standalone mode

mod_cluster for Standalone on the same box

Domain

  1. First you would have to follow all the steps given in the link – How to create cluster in JBoss AS 7.1 in domain mode? and then make the below changes in your domain file.
  2. We would have to add the instance-id attribute in web subsystem as shown below in domain.xml for the respective profile ha and full-ha which is been used.
  3.             <subsystem xmlns="urn:jboss:domain:web:1.1" default-virtual-server="default-host" instance-id="${jboss.node.name}" native="false">
                    <connector name="http" protocol="HTTP/1.1" scheme="http" socket-binding="http"/>
                    <connector name="ajp" protocol="AJP/1.3" scheme="http" socket-binding="ajp"/>
                     .
                     .
                     .
                </subsystem>
    
  4. Last you just have to add the proxy-list in the attribute in mod-cluster-config of modcluster subsystem, which would be having IP Address and Port on which your Apache server is running so that JBoss server can communicate with it, as shown below in domain.xml for the respective profile ha and full-ha which is been used.
  5.         <subsystem xmlns="urn:jboss:domain:modcluster:1.0">
                <mod-cluster-config advertise-socket="modcluster" proxy-list="1.1.1.1:80">
                .
                .
                .
                </mod-cluster-config>
            </subsystem>
    

If everything is configured properly you can hit the URL = http://1.1.1.1/mod_cluster-manager which would show similar below screen. Below image is showing when cluster is been made in on the same box as well as in remote box using domain mode.

Same Box

mod_cluster for Domain mode on the same box

Remote Box

mod_cluster for Domain mode on Remote box

Testing

In all our previous article we had asked you to use one of our application called ClusterWebAp, this is the time when we would be testing if our cluster is working properly with mod_cluster configuration.

  1. Once everything thing is been configured and have been started up properly you can hit the application using Apache URL as shown below and you would see something like in the snap-shot
  2. http://1.1.1.1/ClusterWebApp
    

    ClusterWebApp

  3. Suppose the first request goes to standalone-node2 , you can see there is a session-id which is been generated. Now you just have to shutdown your standalone-node2 and then click on the link Click Here to move to nextPage sessionCheck.jsp on the same page.
  4. Once you click on the link, you will notice that the request has been served by the standalone-node1 this time as node2 had been brought down, but the session-id remains the same which was created earlier having the same timestamp as shown below
  5. Session Replication

With this test it is clear that our cluster is working fine as the session replication is happening properly on JBoss using mod_cluster.

Issues you might face

If you have not given the instance-id in the domain.xml file for ha or full-ha and have a step up a cluster which is having a mod_cluster in front of them you might get the following error in the logs.

[Server:ha-server-1] 20:29:36,429 ERROR [org.jboss.modcluster.mcmp.impl.DefaultMCMPHandler] (ContainerBackgroundProcessor[StandardEngine[jboss.web]]) Error [MEM: MEM: Old node still exist: {4}] sending command CONFIG to proxy 10.10.10.10:80, configuration will be reset
[Server:ha-server-2] 20:29:37,426 ERROR [org.jboss.modcluster.mcmp.impl.DefaultMCMPHandler] (ContainerBackgroundProcessor[StandardEngine[jboss.web]]) Error [MEM: MEM: Can't read node: {4}] sending command STATUS to proxy 10.10.10.10:80, configuration will be reset
[Server:ha-server-2] 20:29:47,432 ERROR [org.jboss.modcluster.mcmp.impl.DefaultMCMPHandler] (ContainerBackgroundProcessor[StandardEngine[jboss.web]]) Error [MEM: MEM: Old node still exist: {4}] sending command CONFIG to proxy 10.10.10.10:80, configuration will be reset
[Server:ha-server-1] 20:29:56,441 ERROR [org.jboss.modcluster.mcmp.impl.DefaultMCMPHandler] (ContainerBackgroundProcessor[StandardEngine[jboss.web]]) Error [MEM: MEM: Can't read node: {4}] sending command STATUS to proxy 10.10.10.10:80, configuration will be reset

For this you just have to follow the step-2 of Domain configuration, which would fix this issue.

If you enjoyed this post, please consider leaving a comment or subscribing to the RSS feed to have future articles delivered to your feed reader.