Architecture of Workflow Management Systems

Architecture of Workflow Management Systems

Reference:

Aalst and Hee, Chaffey, Chapter 5

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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

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Role of Workflow Management Systems

Basic Idea Separation of control and execution

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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

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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

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Reference Model WFMC, 1996

– Workflow Enactment Service

– Process Definition Tools

– Workflow Client Applications

– Invoked Applications

– Other Workflow Enactment Services

– Administration and Monitoring Tools

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WFMC Reference Model

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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


WorkflowEngine(s)

WorkflowEngine(s)

InvokedApplications


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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

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Process definition tools

The resource classification tool

The analysis tool


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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


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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


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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


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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

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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

Worklist Handler

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An Example of Worklist Handler TRANSFLOW {COSA, @Software-Ley}

Invoked Applications

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Interactive Applications Word, Excel, etc.

Fully Automatic Applications Calculations

Invoked Applications

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Process

Definition Tools

Administration

& Monitoring

Tools

Interface 1



Workflow API and Interchange formats

Other WorkflowEnactment Service(s)

WorkflowClient

Applications


WorkflowEngine(s)

WorkflowEngine(s)

InvokedApplications

Other Workflow Enactment Services

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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

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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

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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

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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

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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

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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

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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)


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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


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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.


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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


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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

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Specs for Interchanging Info between workflow products

Interoperability Specifications Specifications for workflow modeling and workflow description (design-time)

Specifications for run-time interoperability


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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


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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

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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

Available Workflow Systems

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TIBCO

Workflow Products

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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

http://www.tibco.com/default.jsp

Workflow Products

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Staffware/TIBCO

Graphical Workflow Definer (GWD)

Graphical Form Designer (GFD)

Work Queue Manager (WQM)

Staffware Server (SS)

Staffware Administration Managers (SAM)

Audit Trail (AT)

Architecture of Workflow Management Systems

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