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the engine process logs. The worklet log entities “Task” and “Case” would also map
to corresponding records in the engine process logs. Thus, by mapping those entity
values, a complete view of the process, inclusive of any actions taken on behalf of
it by the Worklet Service, can be constructed.
It should be noted that the event types for the engine log differ from those of the
worklet log. Since worklets are launched as separate cases in the workflow engine,
the engine’s log records the progress of the process instance, so that it is not neces-
sary to record those types of events in the Worklet Service logs – indeed, to do so
would be a duplication. Thus, the worklet log concentrates on the event details that
are not recorded on the engine side, such as CheckOutWorkItem, WorkletLaunched,
andsoon.

4.9 Conclusion

The worklet approach to dynamic workflow presents several key benefits, including
the following:
A process modeler can describe the standard activities and actions for a work-
flow process and the worklets for particular tasks using the same modeling
methodology
It allows reuse of existing process and worklet components. Removing the dif-
ferentiation between dynamically inserted worklets and the “normal” workflow
aids in the development of fault tolerant workflows out of preexisting building
blocks
Its modularity simplifies the logic and verification of the standard model, since
individual worklets are less complex to build and therefore to verify than mono-
lithic models
It provides for workflow views of differing granularity, which offers ease of
comprehensibility for all stakeholders
It allows for gradual and ongoing evolution of the model, so that global modifi-
cation to the model each time a business practice changes or an exception occurs
is unnecessary
In the occurrence of an unexpected event, an administrator needs simply to
choose an existing worklet or build a new one for the particular context, which
can be automatically added to the repertoire for future use as necessary, thus
avoiding complexities including downtime, model restructuring, versioning prob-
lems, and so on.
Most importantly, the worklet approach is built on the solid theoretical foun-
dations of Activity Theory, and so fully supports the set of derived principles of
organizational work practices, and the criteria for a workflow support system based
on those principles.