How do I set up Web Replication and Persistence?
You can set up a Web cluster following the same procedure as shown in Creating a Cluster Instance. Make sure that you enable the Web Container service for all the nodes. This can be done from the individual server_config.xml files.
Additionally, you need to add the following information in your cluster_config.xml file:
<web-cluster>
<enable>true</enable>
<web-session-persistence>in-memory</web-session-persistence>
<replication-on-all-nodes>true</replication-on-all-nodes>
<web-cluster-persist-info>
<url/>
<driver/>
<user/>
<password/>
<table-name/>
</web-cluster-persist-info>
</web-cluster>
Backup nodes can be setup for a Web cluster only when the <web-session-persistence> is set to in-memory and <replication-on-all-nodes> is set to false. Enable the <web-cluster> by setting enable as true.
There can be two kinds of Web session persistence:
- In-memory Persistence
- Database Persistence
When you select <web-session-persistence> to be in-memory, the HTTP session objects are persisted in memory locally for nodes in the same VM, and persisted through RMI calls for nodes in different VMs.
Whenever there is any state change for Web sessions, the information is replicated across all other nodes. This may prove expensive on memory and hence it is better to set <replication-on-all-nodes> to false. When <replication-on-all-nodes> is set to false, only the backup nodes are notified for replication.
The <web-cluster-persist-info> can be stored in a DB.
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