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The messaging engine (ME) component of the default messaging provider is one of the key services that take advantage of the HAManager to ensure that failover of failed messaging engines can occur to other servers in the cluster. The default messaging provider supports three different HA policies to achieve the failover of a ME in a highly available manner:
This is the default style of peer recovery initiation. If an appserver fails, the HAManager selects another server to perform peer recovery processing on behalf of the failed server.
This style of peer recovery must be explicitly configured. If an appserver fails, the operator can use the Administrative Console to select another server on which to activate the ME.
This style of peer recovery must be configured explicitly. It indicates that external clustering software is monitoring the messaging engine and will failover to an appserver that is configured by the external clustering software to perform the further messaging processing.
Chapter 12 of the IBM WebSphere V6 Scalability and Performance Handbook, SG24-6392 and the WebSphere InfoCenter contain information about messaging engine failover and, specifically, the effect of the One of N and Static policies. This section concentrates on how to use the No Operation policy for ME failover.
The No Operation (NoOP) policy is used in situations where customer requirements dictate great control over when and where messaging engine failover occurs.
