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Workflow Description Language and Workflow Patterns
Yi Wang
Outline What is Workflow? Workflow Management System Workflow Reference Models Workflow Description Language Workflow Patterns
Workflow Definition The automation of a business process, in
whole or part. Information or tasks are passed from one
participant to another for action, according to a set of procedural rules.
A number of logical steps, each of which is known as an activity.
Example of Workflow
Example
Workflow Management System--Definition A system that completely defines, manages
and executes “workflows” through the execution of software whose order of execution is driven by a computer representation of the workflow logic.
Three function areas --Supporting WFM
he Build-time functions, concerned with defining, and possibly modeling, the workflow process and its constituent activities
The Run-time control functions concerned with managing the workflow processes in an operational environment and sequencing the various activities to be handled as part of each process
The Run-time interactions with human users and IT application tools for processing the various activity steps
Types of Workflow Product FlowMark (IBM) Lotus Notes(IBM/Lotus) Ad hoc WorkMAN (Reach Software)
Workflow Reference Model A reference model for workflow
management systems has been defined by the WfMC(Workflow Management Coalition).
Specify a framework for workflow systems, identifying their characteristics, functions and interfaces.
WAPI Workflow Application Programming
Interface The interface around the workflow
enactment A service interface which is to support
workflow management functions across the 5 functional areas.
Workflow Enactment Services A software service Consist of one or more workflow engines in
order to create, manage and execute workflow instances.
Applications may interface to this service via the WAPI.
Workflow Engine A workflow enactment service consists of
mutiple workflow engines. A software service or "engine" Execute environment for a workflow
instance Responsible for the part or all of the
runtime control environment within an enactment service.
Process and Activity State Transitions The workflow enactment service may be
considered as a state transition machine, Individual process or activity instances
change states in response to external events(eg completion of an activity)
Specific control decisions taken by a workflow engine(eg navigation to the next activity step within a process)
A Basic Example
Process Definition Tools To create model, describe and document a
business process. Based on
Process definition language Object relationship model A set of routing commands to transfer
information between participating users
A Basic Meta-Model WFMC is developing a meta-model for the
process definition Meta-Languages is a superset of constructs
that is in process modeling languages
Workflow Description Language A process description, is a structure
describing the tasks or activities to be executed and the order of their execution.
The process description can be provided in Workflow Description Language.
Meta-Language for Workflow and Process Modeling WPDL(Workflow Process Definition
Language) PIF(Process Interchange Framework) PSL(Process Specification Language) GPSG(Generalized Process Structure
Grammars) Unified Modeling Language
A Business Process
Workflow Process Definition Language(WPDL) Defining the actions to be carried out in
each possible state Pre- and post-conditions of states Transitions between states Defining the sequencing of tasks / states Defining automated states and states
requiring user input
PIF Processes are presented at various
levels of abstraction.
Object-Oriented concept of inheritance.
Hierarchy structure.
PIF
PSL(Process Specification Language) To support communication between
different applications based on a common understanding of their environment.
Develop a common exchange format for different modeling description.
A brief summary WPDL, PIF, PSL represent IPO-based
process modeling languages. IPO(Input-Process-Output) IPO-based languages describe a workflow
as a directed graph of activities, denoting the sequence of their execution.
GPSG Generalized Process Structure Grammars.
A constraint-based approach to process modeling.
GPSG example For IPO-based language the sequence of
two activities is denoted as B.start :=A.end
For GPSG, contain following constraints B.start = A.end B.end < deadline B.start = B.end – B.average_duration
Unified Modeling Language Defines different diagram types for the
design object-oriented software systems Helps you specify, visualize, and document
models. Offers graphical notations for workflow
models.
Workflow Patterns A process requires the activation of multiple
tasks. Refers to the relationship among the tasks
of a process. The workflow description languages and
the mechanisms to control the enactment of a case must have provisions to support these temporal relationships.
Basic workflow patterns graph
Basic workflow patterns graph
Reference Internet-Based Workflow Management: Towards
a Semantics Web. Dan.C.Marinescu. Wiley, 2002 Workflow:An Introduction. Rob Allen, Open
Image Systems Inc., United Kingdom Chair, WFMC External Relations Committee
Using Web Services and Workflow Ontology in Multi-Agent Systems. Jarmo Korhonen, Lasse Pajunen, and Juha Puustjärvi
Reference Workflow: An Introduction. Rob Allen, Open Image
Systems Inc., United Kingdom. Chair, WfMC External Relations Committee.
Workflow Process Definition Language-Development and Directions of a Meta-Language for Workflow Processes. Michael zur Mühlen, Jörg Becker
Workflow Management Coalition The Workflow Reference Model Document Number TC00-1003 Document Status - Issue 1.1 19-Jan-95 Author:David Hollingsworth