IBM BPM, V8.0.1, All platforms > Install IBM BPM > Plan for IBM BPM > Plan the ND environment > Topologies of an ND environment

Single Cluster topology pattern

The Single Cluster topology pattern is an IBM-supplied topology pattern. In a Single Cluster topology pattern, all the functions of the deployment environment are combined into a single cluster.

This is the default pattern for IBM BPM for z/OS.

A Single Cluster topology pattern is ideal for limited hardware. Because all the components are installed in the same cluster, fewer physical machines are required. However, because each server instance must run the supporting applications and your integration applications, you need more memory for the individual Java Virtual Machines (JVMs). In addition, one or more members of the cluster must also run the messaging engines required for asynchronous interactions. Thus, the Single Cluster topology pattern is typically used for proof of concept, development, and testing environments.

On non-z/OS platforms, the Single Cluster topology pattern is typically used for testing, proofs of concept, and demonstration environments. However, on z/OS, a Single Cluster topology pattern is a viable production topology. This is because of the different architecture of IBM BPM for z/OS . A Single Cluster topology pattern on z/OS has characteristics that are analogous to the characteristics of the non-z/OS Remote Messaging topology pattern. There are operational advantages to using the Single Cluster topology pattern on z/OS, such as zWLM-managed servant regions.

Combining all aspects of the IBM BPM environment into a single cluster has other implications aside from the increased memory requirements.

If necessary, choose one of the other topology patterns in which the messaging infrastructure is in a separate cluster from the application deployment target.

The Single Cluster topology pattern is suitable for scenarios that are focused on running applications and on synchronous invocations. This topology pattern is also not ideal if you intend to make extensive use of the Common Event Infrastructure (CEI). Generating events and CEI-related messaging traffic, places an additional burden on the cluster members.

From an administrative and scalability perspective, the Single Cluster topology pattern has advantages. A single cluster where each member runs all the IBM BPM components are simpler to administer. Instead of several server instances in multiple clusters, you have a single cluster with fewer members. If the needs of your environment grow, scaling the infrastructure is a simple matter of adding additional nodes and cluster members. Thus, the process of adding capability is simple, but all components are scaled at the same rate.

For example, each additional cluster member adds CEI processing whether you need it or not. If the messaging engines spread across server members use policies, there could be some additional administrative effort in creating and maintaining the policies.

In a Single Cluster topology pattern, all deployment environment functions and functional groups of components run on a single cluster:

Figure 1. Single cluster topology pattern

Topologies of an ND environment