A deployment manager cell can be used for an enterprise service bus that consists of multiple servers, some or all of which are members of server clusters.
A server that hosts queue destinations for SCA modules has one messaging engine in the SCA.SYSTEM bus. For many purposes this is sufficient, but such a messaging engine can only run in the server it was created for. The server is therefore a single point of failure; if the server cannot run, the messaging engine is unavailable. By configuring a server cluster as a bus member instead, the messaging engine has the ability to run in one server in the cluster, and if that server fails, the messaging engine can run in an alternative server. This is illustrated in Figure 1.
Another advantage of configuring a cluster bus member is the ability to share the workload associated with an SCA module across multiple servers. For an SCA module deployed to a cluster bus member, the queue destinations used are partitioned across the set of messaging engines run by the cluster servers. The messaging engines in the cluster each handle a share of the messages passing through the SCA module.
To summarize, with a cluster bus member you can achieve either failover, workload sharing, or both, depending on policies that you can configure.
There are several different ways to create a multiple-server enterprise service bus: