Architecture of Workflow Management Systems
Reference:
Aalst and Hee, Chaffey, Chapter 5
COMP 5524 1
Role of Workflow Management Systems
How IS are traditionally structured?
No separation of Process Management from the application software
Process Management Hidden inside the IS
Little attention to process structure Often difficult to actually recognize the business process
COMP 5524 2
Role of Workflow Management Systems
Basic Idea Separation of control and execution
COMP 5524 3
workflow management
system
application
control (process logistics)
execution (task oriented)
Separating Management/Applications
Advantages
Reuse the same functionality in more than one task
Rearrange the business process at a later stage
Possible to integrate new applications with legacy systems
The process execution is more manageable, with progress and bottlenecks being more easy to check
COMP 5524 4
A Reference Model Why Needed?
– Workflow management has many faces
Confusion may arises what actually can be expected from functionality of WFMS
– Standardizing workflow terminology, Defining standards for the exchange of data between WFMS and applications
– WFMC Workflow Reference Model
General description of architecture of WFMS
COMP 5524 5
Reference Model WFMC, 1996
– Workflow Enactment Service
– Process Definition Tools
– Workflow Client Applications
– Invoked Applications
– Other Workflow Enactment Services
– Administration and Monitoring Tools
COMP 5524 6
WFMC Reference Model
COMP 5524 7
Process
Definition Tools
Administration
& Monitoring
Tools
Interface 1
Interface 4Interface 5
Workflow Enactment Service
Workflow API and Interchange formats
Other WorkflowEnactment Service(s)
WorkflowClient
Applications
Interface 3Interface 2
WorkflowEngine(s)
WorkflowEngine(s)
InvokedApplications
Workflow Enactment Service
COMP 5524 8
Heart, May consist of several workflow engines
Workflow Engine
Creating new cases and removing completed ones
Routing cases, using interpretation of process definition
Submitting work items to the correct resources (employees), based upon resource classification
Managing and handling triggers
Starting up application software during the performance of an activity
Recording historical data
Providing a summary of the workflow
Monitoring the consistency of the workflow
Process Definition Tools
COMP 5524 9
Process definition tools
The resource classification tool
The analysis tool
Process Definition Tools
COMP 5524 10
Functionality
Ability to establish process definitions (name, description, date, version, components, and so on)
Ability to model sequential, parallel, selective and iterative routing by means of such graphic components as the AND-split, AND-join, OR-split and OR-join
Version-management support (after all, there may be several versions of the same process)
Definition of case attributes used in the process
Task specification
Checking of the (syntactical) correctness of a process definition and the tracing of any inconsistencies
Process Definition Tools
COMP 5524 11
Following is established for each task Name and description of the task
Task information any instructions and supporting information for the employee performing the task
The requirements with respect to the resource carrying out the task Example a specification of its role and organizational unit, or information
about the separation of functions
The task's routing characteristics (AND-split, AND-join, OR-split, OR-join)
The specification of any triggers required
Instructions for the workflow engine Example priorities, case management and resource management
Process Definition Tools
COMP 5524 12
Resource Classification Tool
A list of the resource classes, often subdivided into roles (based upon qualifications, functions and skills) and organizational units (based upon arrangement into teams, branches and/or departments)
Any specific characteristics of a resource class
Relationship between the various resource classes Example a hierarchy of roles or organizational units
Process Definition Tools
COMP 5524 13
The Analysis Tool
Before a workflow which has been defined can go 'into production', it is first useful to analyze it
Checking semantic correctness
Performing simulations
Current Systems Limited analysis capabilities
Workflow Client Applications
COMP 5524 14
The Standard Worklist Handler
Shows work items to be carried out
Allocation Pull or Push driven
Basic Functionality Work item presentation
Properties of work items (case, task info)
State (Start and reporting completion)
The Integrated Worklist Handler
Customized worklist handler Supporting facilities alongside the standard functionality described above Example Processing similar cases in batch; processing a series of
successive tasks for a case
Invoked Applications
COMP 5524 16
Interactive Applications Word, Excel, etc.
Fully Automatic Applications Calculations
Invoked Applications
COMP 5524 17
Process
Definition Tools
Administration
& Monitoring
Tools
Interface 1
Interface 4Interface 5
Workflow Enactment Service
Workflow API and Interchange formats
Other WorkflowEnactment Service(s)
WorkflowClient
Applications
Interface 3Interface 2
WorkflowEngine(s)
WorkflowEngine(s)
InvokedApplications
Other Workflow Enactment Services
COMP 5524 18
Several workflow engines
Same management, use the same workflow definitions
Such engines Belong to the same workflow domain
However, it is also possible to link several autonomous workflow systems with one another Cases (or parts of cases) can be transferred from one system to
another
This means that the Workflow Enactment Services of each system are linked Workflow interoperability
Administrative and Monitoring Tools
COMP 5524 19
Operation Management Tool
Not case-related (resource-related or system-related) Addition or removal of staff
Input/revision of an employee's details (name, address, telephone number, role, organizational unit, authorization and availability)
Case related Inspection of the logistical state of a case
Manipulation of the logistical state of a case due to problems and exceptional circumstances
Revision of schedule/availability (sick leave, holidays, etc.)
Administrative and Monitoring Tools
COMP 5524 20
Recording and Reporting tool
Historical data which may be useful for management
Example Performance Indicators • average completion time for a case
• average waiting time and processing time (every task)
• percentage of cases completed within a fixed standard period
• average level of resource capacity utilization
Info about the properties of completed workflow is crucial for management
Clear link with data mining, data warehousing, OLAP
Users of WFS
COMP 5524 21
Historical data which may be useful for management
workflowmanagement
systeem
administrator
process analist
workflowdesigner
end-user
manager
applicationdesigner/
programmer
databasedesigner/
programmer
applications
Roles of People Involved
COMP 5524 22
Workflow Management System (types of users)
The Workflow Designer
The Administrator
The Process Analyst
The Employee Not clear cut; Process analysts may be manager, employee also admin, types of admin
Applications
Database designers/programmers
Application designers/programmers
Data in Workflow System
COMP 5524 23
Process Definition Resource
classifications Analysis data
Operational
management data
The definitions of
processes and tasks.
Roles
Organizational
units
The results of any
analyses carried out
(simulation)
Technical
configuration
(system Parameters)
Staff
Case-related data
Historical data Application data Internal data Logistical
management data
Progress of an
individual case
Cause of a
problem
Performance of
the business
process
Case data
(individual)
Master data
(customers and
suppliers)
Worklists which
are active
Sate of each
engine
Network addresses
Case states
State of each
resource and the
triggers available
Interfacing Problems
COMP 5524 24
WFMC Recognizes Five Interfaces
Why Interface Standardization?
Improve the exchange of data between WFMS parts
Create links between different manufacturers enactment servers in a simple way
Enable the development of applications that are entirely independent of chosen WFMS
Every interface will be achieved using Application Programming Interface (API)
Interfacing Problems
COMP 5524 25
Interface 1 •Connect/disconnect •Process definitions and resource classifications •Opening, creating and saving a process definition
Interface 2 •Connect/disconnect production of case •Work item state summaries •Generation of new cases •Beginning, interruption and completion of activities
Interface 3 •Application is opened from the system through interface 3. (also can opened from the worklist handler)
Interface 4 Other Workflow Enactment Services
Interface 5 •Management
•Addition of an employee •Permission of authorization •Execution of a process definition
•Track •Waiting times •Completion times •Processing times •Routing •Staff utilization
Interfacing Problems
COMP 5524 26
An application can be started by an engine and/or from a worklist handler.
An application is called to perform a task.
This application will probably modify application data in database - If the workflow engine does not become accessible following the execution of the Application due to a system error, the engine and the application will be 'out of sync’.
Once the system has been corrected, the engine will have no choice but to roll back the task.
Interfacing Problems
COMP 5524 27
ACID Properties must be held
Atomicity
A task is either completed in full (Commit) or
Restarts from the very beginning (Rollback)
Consistency
The result of an activity leads to a consistent state
Isolation
Tasks performed at the same time must not influence one another
Durability
Task is successfully completed
The result must be saved
Completed with a commit – results cannot be lost
Interfacing Problems
COMP 5524 28
In the financial world, we frequently have to ‘pass the ACID test’
Linking two or more workflow systems People, most of the workflow management systems is not always entirely clear what the state of a case is
Interoperability Standards
COMP 5524 29
Specs for Interchanging Info between workflow products
Interoperability Specifications Specifications for workflow modeling and workflow description (design-time)
Specifications for run-time interoperability
Interoperability Standards
COMP 5524 30
Design Time Corresponds to Interface 1 Process Definition Tools WPDL (WFMC’s Process Definition Language)
PIF (Process Interchange Format) Process descriptions can be exchanged automatically without using different translators for each pair of systems
Process modelers Workflow systems Process repositories
PSL (Process Specification Language ) by NIST
Interoperability Standards
COMP 5524 31
Run Time
Interface Interface 2 Workflow Client Application Interface 3 Invoked Application Interface 4 Other Workflow Enactment Service
Standards WFMC SWAP WF-XML OMG’s jointFlow
Required Technical Infrastructure
COMP 5524 32
Most Wokflow System Client/Server Central Server Windows Vista/NT/2000, UNIX Clients Windows Vista/NT/2000, UNIX
Client Worklist Handler User Interface Application
Server Workflow engine Application DBMS Application data
Workflow Products
COMP 5524 34
TIBCO ® Staffware Leading workflow management system (typically 25 percent
of the global “pure” workflow market)
is headquartered in Maidenhead Palo Alto USA
Focuses on performance and reliability rather than functionality (e.g. infinite scalability, fault tolerance, etc.)
HK Housing Society, New World Mobility, CLSA, etc. • Certification/Education Program (Wan Chai)
TIBCO Staffware Process Suite (SPS) • Design tool and modeling language • Show the management/administrator tools • Demonstrate the end-user’s view • Show the need for analysis
Top Related