Session Replication in Tomcat

Question

We have two separated servers and configured with Delta session manager to replicate session between two servers. The replication between them was successful and if I down any one of the server it works fine, but it always shows an error at catalina.out that

object are not serialized

Answer 1

In case of Apache Tomcat 7 we can uncomment <Cluster className=”org.apache.catalina.ha.tcp.SimpleTcpCluster”/> tag and update cluster detail something liek below.

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster">
    <Manager className="org.apache.catalina.ha.session.DeltaManager"
        expireSessionsOnShutdown="false"        
        notifyListenersOnReplication="true"/>
    
    <Channel className="org.apache.catalina.tribes.group.GroupChannel">
    
        <Membership className="org.apache.catalina.tribes.membership.McastService"
        address="228.0.0.4"
        port="45564" frequency="500"
        dropTime="3000"/>           

        <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">                
            <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>              
        </Sender>           
        
        <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver" 
        address="auto" port="4000" autoBind="100"
        selectorTimeout="5000" maxThreads="6"/>                     
        
        <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>         
        <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor"/>   
        <Interceptor className="org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor"/>                      
    
    </Channel>
    
    <Valve className="org.apache.catalina.ha.tcp.ReplicationValve" />       
    <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener" />       
    
</Cluster>

Also, we need to add workers.properties at apache/conf/ path.

Please note this file has to be placed in all the Tomcat servers which will run in a cluster.

You can read more in detail here.