This topic applies only to the IBM Business Process Manager Advanced configuration.

Expanding your topology

There are three ways to expand your topology: adding members to a cluster, adding cells, or adding deployment environments.

Adding cluster members

The easiest way to expand your infrastructure is to add more cluster members to your existing clusters. You can add cluster members to each cluster independently or in combination, depending on where you see the need for growth. In a single-cluster topology, you can expand the cluster (which provides the application, support, and messaging capabilities). In a three-cluster topology with separate application cluster, support cluster, and messaging cluster, you can add new cluster members for any one, any two, or all three clusters. By expanding your clusters in this way, you can improve your application throughput.

Consider adding cluster members when one of the following situations occurs:

You plan to deploy new applications to your existing environment.
You anticipate increased volume requirements for your existing applications.
You need more capacity for operational purposes, such as failover.

However, there are some cases where expanding existing clusters is not appropriate. Consider another solution in the following cases:

You have applications or sets of applications that serve different business purposes and you want to keep them distinct. If you deploy these distinct applications to the same deployment environment, you might introduce dependencies between otherwise unrelated business domains. Dependencies can affect such things as maintenance schedules and application availability when, for example, unrelated applications are less reliable.
After you analyze your performance characteristics, you realize that planned deployments might push your system beyond the limits of the current deployment target. They might introduce too many modules from new applications or new versions of applications to run in the existing memory space, or use your database tables too heavily.

For information about how to add cluster members using the Deployment Environment wizard or the BPMConfig command, see the topics Using the Deployment Environment wizard and BPMConfig command-line utility.

Adding cells

If you decide that expanding your existing clusters is not an appropriate solution, you can create another deployment environment in another cell. This approach provides the following advantages:

The most room for growth
The most flexibility for expanded functional requirements
Complete isolation for your applications

While this approach is similar to an approach where multiple deployment environments are used, it removes the deployment manager as a common point of failure. It also enables you to avoid sharing IBM BPM installations, which makes it easier to apply fixes and updates to one environment at a time and provides more isolation for the applications.

To create a new cell and IBM BPM environment, you follow the same steps used to set up the first environment. If desired, you can use new unique names for the cell, deployment manager, and deployment environment.

Adding deployment environments

If the previous two options do not satisfy your requirements, there is a third alternative for expanding your topology. You can create multiple independent deployment environments for your applications in the same cell.

Consider adding deployment environments when one of the following situations applies:

You want to reuse complex configurations at the cell level. For example, you want to set up multiple test environments quickly without having to configure security or nodes each time.
You want the convenience of a single IBM® Process Center and a single administrative console to manage multiple IBM Process Server servers.
You want to avoid the larger footprint associated with adding cells.
You must expand the capacity of your environment but adding cluster members is not an appropriate solution.
You want to isolate process applications into separate Java virtual machines (JVMs), associating each application group with a specific set of JVMs.

Only one Process Center deployment environment is permitted for each cell, but multiple Process Server environments are permitted. Although it is permitted to share the Process Center cell with Process Server deployment environments, it is not recommended due to upgrade complications.

When you create additional deployment environments after creating the first deployment environment, the cell-scoped configuration artifacts already exist and they will be reused because they are shared. You create the additional deployment environments in the same way that you created the first deployment environment.

Running multiple deployment environments in the same cell is an advanced topology that requires research and planning.