Download PDF (1.3 MB) - IBM Redbooks

Choose between business state machines and business processes
Business state machines (BSMs) provide an attractive way of implementing business flow
logic. For some applications, it is more intuitive to model the business logic as a state
machine, making the resultant artifacts easier to understand. However, a BSM is
implemented using the business process infrastructure, so there is always a performance
impact when choosing BSM over business processes.
If an application can be modeled using either BSM or business processes, and performance
is a differentiating factor, choose business processes. Also, more options are available for
optimizing business process performance than for BSM performance.
Minimize state transitions in business state machines
Where possible, minimize external events to drive state transitions in BSMs. External
event-driven state transitions are costly from a performance perspective. In fact, the total time
it takes to run a BSM is proportional to the number of state transitions that occur during the
life span of the BSM.
For example, if a state machine transitions through states A B B B C (four
transitions), making transitions through states A B C (two transitions) is twice as
time-consuming. Also, automatic state transitions are much less costly than event-driven
state transitions. Consider these principles when designing a BSM.
2.3 Topology
In this section, we provide information about choosing an appropriate topology for your
solution.
2.3.1 Deploy appropriate hardware
It is important to pick a hardware configuration that contains the resources necessary to
achieve high performance in a Business Process Manager environment. The following factors
are key considerations in picking a hardware configuration:
► Processor Cores
Ensure that Business Process Manager servers (Process Servers and Process Centers)
are installed on a modern server system with multiple processor cores. Business Process
Manager scales well, both for single JVM servers through symmetric multiprocessing
(SMP) scaling, and horizontally through clustering.
► Memory
Business Process Manager servers benefit from both a robust memory subsystem and an
ample amount of physical memory. Ensure that the chosen system has server-class
memory controllers and as large as possible L2 and L3 caches (optimally, use a system
with at least a 4 MB L3 cache). Make sure that there is enough physical memory for all the
combined applications (JVMs) that are expected to run concurrently on the system. For
64-bit JVMs (the recommended configuration), 4 GB per JVM is needed if the maximum
heap size is 3 GB or less. Add additional physical memory for heap sizes larger than 3 GB.
When using a 32-bit JVM, a rough guideline is 2 GB per JVM instance.
► Disk
Ensure that the systems hosting the message and data stores (The Process Server
nodes, and the database tiers), and also the Process Server and Process Center cluster
members, have fast storage. Fast storage typically means using Redundant Array of
Chapter 2. Architecture best practices 13