Glassfish 3.1 – Clustering Tutorial Part2 (sessions)

In the previous part (link) I get you running with a simple Glassfish 3.1 cluster setup with 2 instances running on 2 nodes. Now we have a cluster setup and can deploy an application one time and it will run on both nodes, no big deal, it doesn’t get us anywhere. So in part 2 we will do some modifications to our virtualbox server setup and create a web application with sessions replicated to both instances.

Prerequisites:

  • The server and cluster setup from part 1 (link)

Preparation of host and Virtualbox guests:

In part 1 we used n1 and n2 as hostname, this creates trouble for this part. A key information for the sessions is the server-hostname (domain) and we cannot share sessions between totally different hosts.

  1. Update guest server hostname
    Change etc/hosts and /etc/hostname
    Server n1 becomes n1.test.com

    127.0.0.1    localhost
    127.0.1.1    n1.test.com
    127.0.0.1    n1.test.com
    192.168.56.102  n2.test.com
    

    Server n2 becomes n2.test.com

    127.0.0.1    localhost
    127.0.1.1    n2.test.com
    127.0.0.1    n2.test.com
    192.168.56.101  n1.test.com
    

    Remarks:

    • You can use any domain name (other than test.com, which I dont own btw).
    • The IP addresses must fit your own Virtualbox setup.
  2. Update your host
    The host running Virtualbox. Change /etc/hosts

    192.168.56.101  n1.test.com
    192.168.56.102  n2.test.com
    
  3. Check multicast
    The communication between the nodes is using multicast for the session replication. The Glassfish team gives us a tool to verify if your servers can “see” each other.
    Go to the bin folder of the Glassfish installation and execute ./asadmin validate-multicast on both nodes
    You should get feedback like this Continue reading
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