Production topologies of BPM / BAW, from simplest to most robust (the names are IBM's deployment environment patterns):
- Single Cluster - one WebSphere cluster runs everything (application / process engine, messaging engine, support: PDW, event manager). 2+ members on 2 nodes give HA. Simplest to operate; the default for most installations since BPM 8.5.
- Three Clusters (Application, Messaging, Support) - the "remote messaging and remote support" pattern: the SIBus messaging engines and the support functions (Performance Data Warehouse, event manager, mediation for Advanced) run in their own clusters so that heavy reporting or messaging does not compete with user requests. Chosen for large loads or when the PDW is used heavily; more JVMs to tune.
- Four Clusters (Advanced) - BPM Advanced adds a Web cluster for Business Space / REST gateway components; rare today.
- Process Center + Process Servers - in every case the development repository (Process Center, its own cell) is separate from the runtime cells (Process Server: test, staging, production), connected online (Process Center pushes snapshots) or offline (installation packages).
- Golden topology extras: IHS / load balancer in front (question 2894), databases on an HA cluster (Db2 HADR, Oracle RAC), shared file system for the SIBus file store or a database store, DR cell in a second data centre with database replication (question 99).
- Containers (CP4BA) - no clusters to design: the operator deploys the Workflow Server as pods (replicas), the messaging as Liberty embedded / MQ, BAI for analytics; scaling = replica counts and pod sizes; the "environments" are separate namespaces or OpenShift clusters.
How to choose: number of concurrent users and instances per day, whether the PDW / reports are used, how much event manager work (timers, UCAs) exists, the required uptime (rolling restarts need 2+ members), and the team's operations skills. Most new deployments in 2024 are CP4BA on OpenShift; most existing traditional ones run Single Cluster with two or three members.
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