Workflow Management Systems: Functions, architecture, and products'

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Workflow Management Systems Functions,
architecture, and products.
Wil van der Aalst

• Eindhoven University of Technology
• Faculty of Technology Management
• Department of Information and Technology
• P.O. Box 513
• 5600 MB Eindhoven
• The Netherlands
• w.m.p.v.d.aalst_at_tm.tue.nl

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Focus on "classical" workflow management systems,
but ...

• Four types of "workflow-like" systems
• Information systems with hard-coded workflows
  (process organization specific).
• Custom-made information systems with generic
  workflow support (organization specific).
• Generic software with embedded workflow
  functionality (e.g., the workflow components of
  ERP, CRM, PDM, etc. systems).
• Generic software focusing on workflow
  functionality (e.g., Staffware, MQSeries
  Workflow, FLOWer, COSA, Oracle BPEL, Filenet,
  etc.).

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Basic idea
workflow management system
control (process logistics)
execution (task oriented)
application

• Separation of control and execution.

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WfMC Reference model
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Data inside a WFS
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Interfaces
Weak!
Demos
Published in Handbook
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Potential problem
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• The ACID-properties, known from transaction
  processing, should hold.
• Atomicity(atomic, "everything or nothing",
  rollback if necessary)
• Consistency(a completed task results in a proper
  state of the system)
• Isolation(tasks do not affected each other, even
  if they are executed in parallel)
• Durability(the result of a completed task may
  not get lost commit tasks)

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Users of a WFS
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Examples of systems

• COSA (demo)
• Staffware
• FLOWer

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Staffware

• Leading workflow management system (typically 25
  percent of the global pure workflow market).
• Staffware PLC is headquartered in Maidenhead UK
  and has offices in 19 countries.
• Focus on performance and reliability rather than
  functionality (e.g., infinite scalability, fault
  tolerance, etc.)
• In the remainder, we present a small case study
  that is used to
• introduce the design tool and modeling language
  of Staffware,
• show the management/administrator tools of
  Staffware,
• demonstrate the end-users view of Staffware, and
• show the need for analysis.

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WfMC reference model
(1)
(2)
(3)
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A small case study Double Check (DC)

• Processing of insurance claims involving
  registration, two checks, and a payment of
  rejection
• Five tasks
• register (register insurance claim)
• checkA (check insurance policy)
• checkB (check damage reported)
• pay (pay for the damage)
• reject (inform customer about rejection)
• Registration is followed by two checks which can
  be handled in parallel.
• Each of the checks results in OK or not OK.
• If both are OK, pay otherwise reject.
• Three roles register (for task register), checks
  (for both checks), and pay/reject (for final
  tasks).

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Staffware The designers view
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Building blocks
start
stop
step (i.e., task)
wait (i.e., AND-join)
event step
condition (i.e., XOR-split)
complex router (OR-join/AND-split)
automatic step
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Basic semantics of a step
AND-split
OR-join
Same for complex routers, conditions (input OR,
output each branch is AND), other types of
steps, etc.
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Advanced semantics
withdraw construct
time-out construct
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Defining the process Double Check (DC)
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Adding a step
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Defining a step
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Defining a step (2)
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Defining forms and case variables
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Building a sequence
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Another step definition
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Another form definition
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Adding a set in parallel
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Another step definition
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Synchronizing two flows
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Another step definition
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Defining conditions
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The alternative route
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Another step definition
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Staffware The manager/administrators view
Monitoring and managing processes and cases
Managing users/groups
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Managing users
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Managing groups
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Making backups
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Managing Staffware tables
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Managing processes and cases
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Monitoring individual cases
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Managing Staffware lists
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Managing nodes
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Releasing changes
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The end-users view
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Selecting and executing the first step
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Executing one of the two parallel steps
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Executing the other one
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Executing the final step
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Audit trail
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Analysis of Staffware processes
6 runs (8 sequences) are possible!
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Example audit trails
One not OK
Both OK
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Example audit trails (2)
Both not OK (seq)
Both not OK (par)
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Analysis using Woflan
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Improved process
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Possible scenarios
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Analysis using Woflan
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Exercises Staffware
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Translate to notation of book/course
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Translate to notation of book/course
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Model in Staffware
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Model in Staffware
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Model in Staffware
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Some more examples ...
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• Four types of "workflow-like" systems
• Information systems with hard-coded workflows
  (process organization specific).
• Custom-made information systems with generic
  workflow support (organization specific).
• Generic software with embedded workflow
  functionality (e.g., the workflow components of
  ERP, CRM, PDM, etc. systems).
• Generic software focusing on workflow
  functionality

SAP Business Workflow/Webflow (SAP AG)
FLOWer (Pallas Athena)
Oracle BPEL (Oracle)
Staffware (TIBCO)
COSA (COSA GmbH)
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SAP Business Workflow/Webflow (SAP AG)
Staffware (TIBCO)
Oracle BPEL (Oracle)
COSA (COSA GmbH)
FLOWer (Pallas Athena)
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COSA (COSA GmbH)
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COSA Control flow perspective

• Based on Petri nets
• Lots of functionality

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COSA Resource perspective

• One of the most powerful tools on the market.
• Multiple dimensions and rules.

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Oracle BPEL (Oracle)
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Oracle Control flow perspective

• Based on BPEL

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BPEL(4WS) Business Process Execution Language
for Web Services

• Compromise between IBM and Microsoft.
• Merges WSFL and XLANG.
• Two styles of working graph based and
  structured.
• Expressive but complex language.
• Support by many vendors IBM Websphere, Oracle
  BPEL, and at least 16 more products.
• In April 2003, BEA Systems, IBM, Microsoft, SAP
  AG and Siebel Systems submitted BPEL4WS 1.1 to
  OASIS.
• Version 2.0 will have subtle but significant
  differences.
• Two flavors executable and abstract
  (non-executable)

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Constructs

• Primitive activities
• invoke, invoking an operation on some web
  service
• receive, waiting for a message from an external
  source
• reply, replying to an external source
• wait, waiting for some time
• assign, copying data from one place to another
• throw, indicating errors in the execution
• terminate, terminating the entire service
  instance and
• empty, doing nothing.

• Structured activities
• sequence, for defining an execution order
• switch, for conditional routing
• while, for looping
• pick, for race conditions based on timing or
  external triggers
• flow, for parallel routing and
• scope, for grouping activities to be treated by
  the same fault-handler.
• Activities can be nested.
• Can be connect though links.

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Oracle Resource perspective

• Not part of BPEL (cf. BPEL4people).
• Oracle specific task implementations.
• Close to programming.

See Pattern-based Evaluation of Oracle-BPEL
(v.10.1.2), N.A. Mulyar, 2005.
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SAP Business Workflow/Webflow (SAP AG)
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SAP Control flow perspective

• Two views native view and EPC view.
• Block structured.
• e.g. sequence

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Routing elements
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parallel routing
three types of choices
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join can hove a condition and/or lower bound
two types of loops
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SAP Resource perspective

• Organizational units have positions that may or
  may not be occupied.
• Positions may be associated to multiple jobs
  (kind of role).
• You can assign a task to
• an organizational unit, if it is to apply to all
  subordinate positions
• a job, if it is to apply to all positions
  described by the job
• a position, if it is to apply to those persons
  (employees) or users who hold the position
• a person (employee), if it is to apply to this
  person

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Logging in SAP Workflow
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FLOWer (Pallas Athena)
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FLOWer Control flow perspective

• Block structured (similar to BPEL) but with
  excellent support for multiple instances.
• Can be generated from Protos.
• Case handling principle.

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Partly block structured choices, loops, etc.
require an additional level
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FLOWer Resource perspective

• Three roles for step in the process (execute,
  redo, skip).
• Hierarchies can be defined independent of
  process.
• Various was to view/distribute work.

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Forms
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