High Availability Edition
The optional High Availability (HA) capability installs automatically and makes the Application Server highly available and load balanced. Normally used in carrier-class or very large deployments.You can also configure Oracle database installations for failover (see Oracle Failover).
You can test failover by stopping a server process.
In this edition, primary and secondary paired mediation servers use configurable heartbeats to monitor each others status. If the secondary mediation server detects that the primary is down, it will take over. The Application Server also monitors the mediation server and will generate an event/alarm if the primary mediation server goes down. Configurable trap buffers reduce trap loss during failover.
Primary and secondary clustered Application Servers also use configurable heartbeats to monitor each others status. If the primary fails, the secondary will take over and will also generate an event/alarm. Clients and mediation servers identify applications servers by partition name. This is the same for the primary and secondary Application Server, so the failover is transparent to the clients and mediation servers.
If you want to extend this to the database, Oracle Real Application Clusters (RAC) handle database replication, synchronization and failover. Application Servers identify Oracle by Service Name which is the same for all Oracle hosts, so failover between Oracle hosts is transparent to this application.
You can also have a form of HA at the application level with transaction management. For example:
HA installations support the following:
• Application Server clustering (with SonicMQ JMS)
• Mediation server load balancing (with the Application Server round robin process)
• Mediation server failover
• Supports Database replication (must have Oracle Parallel Server, Oracle’s Real Application Cluster [RAC] or equivalent, database).