Memory-to-memory topology: Peer-to-peer function
The peer-to-peer topology is the default configuration and has a single replica. You can add additional replicas by configuring the replication domain.
In this basic peer-to-peer topology, each server JVM can:
- Host the Web application leveraging the HTTP session
- Send out changes to the HTTP session that it owns
- Receive backup copies of the HTTP session from all of the other servers in the cluster
This configuration represents the most consolidated topology, where the various system parts are collocated and requires the fewest server processes. When using this configuration, the most stable implementation is achieved when each node has equal capabilities (CPU, memory, and so on), and each handles the same amount of work.
When using the peer-to-peer topology one session replication backup must run at all times for invalidation to occur. For example, if you have a cluster of 2 appservers, server1 and server2, that are both configured in the peer-to-peer mode and server2 goes down. All of backup information for server1 is lost and those sessions are no longer invalidated properly.
Session hot failover
Session hot failover is only applicable to the peer-to-peer mode.In a clustered environment, session affinity in the WAS plug-in routes the requests for a given session to the same server. If the current owner server instance of the session fails, then the WAS plug-in routes the requests to another appropriate server in the cluster. For a cluster configured to run in the peer-to-peer mode this feature causes the plug-in to failover to a server that already contains the backup copy of the session, therefore avoiding the overhead of session retrieval from another server containing the backupnewfeat .
You must upgrade all WAS plug-in instances that front the Application Server cluster to version 6.0 to ensure session affinity when using the peer-to-peer mode.
Related concepts
Memory-to-memory replicationMemory-to-memory topology: Client/server function
Memory-to-memory session partitioning
Related tasks
Configure memory-to-memory replication for the peer-to-peer mode (default memory-to-memory replication)Configure memory-to-memory replication for the client/server mode