process-flexibility.com

Thursday, 13 June 2013 11:09

Pattern PP3: Late Composition of Process Fragments

This pattern enables the on-the fly composition of process fragments from the process repository, e.g., by dynamically introducing control dependencies between a predefined set of fragments. There is no predefined plan, but the process instance is created in an ad-hoc way by selecting from the available activities in the repository. In addition, constraints may be defined, which have to be considered while composing a process fragment (Design Choice A). The Interleaved Routing pattern – one of the workflow patterns – can be seen as a special implementation of PP3. It allows for the sequential execution of a set of activities, whereby the execution order is decided upon at run-time and each process fragment has to be executed exactly once. Like for pattern PP3 decisions about the exact control flow structure are deferred to run-time. The Interleaved Routing pattern corresponds to Design Choice A[2] of PP3 as the composition has to to obey certain constraints (i.e., on how often a particular activity has to be executed).

Description

At build-time a set of process fragments is defined from which the schema of a concrete process instance can be composed during run time. This can be achieved by dynamically selecting fragments and by specifying the control dependencies between them on the fly

Example

Different kinds of medical examinations are accomplished in a hospital. The exact examinations to be applied to a particular patient and the order in which they are performed are defined for each patient individually depending on his/her medical problems.

Problem

There exist several variants of how process fragments can be composed. To reduce the number of process variants to be specified by the process engineer during build time, process instances are dynamically composed from a given set of fragments.

Design Choices 

  1. What are the basic building blocks for late modeling?
    1. All process fragments from the repository can be chosen.
    2. A constraint-based subset of the process fragments from the repository can be chosen.
    3. New activities or process fragments can be defined.

PP3

Animation

View Animation

Read 913 times
 

Get the Book!

book cover small