analysis of workflows : verification, validation, and performance analysis
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Eindhoven University of Technology Faculty of Technology Management Department of Information and Technology P.O. Box 513 5600 MB Eindhoven The Netherlands [email protected]. Analysis of workflows : Verification, validation, and performance analysis. Wil van der Aalst. - PowerPoint PPT PresentationTRANSCRIPT
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Analysis of workflows: Verification, validation, and performance analysis.
Wil van der Aalst
Eindhoven University of TechnologyFaculty of Technology ManagementDepartment of Information and TechnologyP.O. Box 513 5600 MB EindhovenThe [email protected]
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Queuing models
Basic characteristics:
• average number of arrivals per time unit: (mean arrival rate)
• average number that can be handled by one server per time unit: (mean service rate)
• number of servers: c
arrivals waiting service
c
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Queuing models (2)
Basic relationships:
• average time between arrivals: 1/• average service time: 1/• occupation rate: c*)
• average number being served: r
c
W,Lq
S,LW (S) = average time in queue (system)Lq (L) = average number in queue (system)
• L = Lq + r
• S = W + 1/• Lq = * W
• L = * S (Little’s formula)
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M/M/1 queue
1
• Lq = (• L = • W = • S =
Assumptions:
• time between arrivals and service time follow a negative expontential distribution
• 1 server (c = 1)
• FIFO
Also formulas for M/Er/1, M/G/1, M/M/c, ... !
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Exercise
Calculate:
• occupation rates,
• average waiting time,
• average throughput time,
• average number in system.
task1b
task1a
c3
c1
c216 difficultcases per hour
c23
c22
1 resource, averageservice time of 8 minutes
1 resource, averageservice time of 2.66 minutes
task2
1 resource, averageservice time of 2minutes
18 easy casesper hour
difficult cases
easy cases
Increase the occupation rate until 90%:
• average waiting time,
• average throughput time,
• average number in system.
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Simulation
• Random walk through the reachability graph
• Computer experiment
– pseudo random numbers
– random generator
• Validation
• Statistical aspects
– start run
– subruns
• Animation
• Flexible
• No proof!
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Workflow Management Systems: Functions, architecture, and products.
Wil van der Aalst
Eindhoven University of TechnologyFaculty of Technology ManagementDepartment of Information and TechnologyP.O. Box 513 5600 MB EindhovenThe [email protected]
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Focus on "classical" workflow management systems, but ...
Four types of "workflow-like" systems:
1. Information systems with hard-coded workflows (process& organization specific).
2. Custom-made information systems with generic workflow support (organization specific).
3. Generic software with embedded workflow functionality (e.g., the workflow components of ERP, CRM, PDM, etc. systems).
4. Generic software focusing on workflow functionality (e.g., Staffware, MQSeries Workflow, FLOWer, COSA, Oracle BPEL, Filenet, etc.).
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Basic idea
• Separation of control and execution.
workflowmanagement
system
application
control (process logistics)
execution(task oriented)
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WfMC Reference model
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
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Data inside a WFS
procesdefinition
tool
resourceclassification
tool
analysis
tool
procesdefinitions
resourceclassifications
analysisdata
workflow
engine(s)
registration
generator
operationalcontroldata
historicaldata
internaldata
Logisticalcontroldata
otherworkflowsystems
customizedin-basket
standardin-basket
automaticalapplications
interactiveapplications
applicationdata
operational
tool
triggers
control
tool/report
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Interfaces
ProcessDefinition Tools
Administration& Monitoring
Tools
Interface 1
Interface 4Interface 5 Workflow Enactment Service Other WorkflowEnactment Service(s)
WorkflowClient
Applications
Interface 3Interface 2
WorkflowEngine(s)
WorkflowEngine(s)
InvokedApplications
Published in Handbook
Demo’s
Weak!
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Potential problem
workflowmanagement
system
application
In-basket application
server
client
database
Interface 3
workflowengine
DBMS
in-basket(worklist)
applications
server client
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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
workflowmanagement
systeem
administrator
process analist
workflowdesigner
end-user
manager
applicationdesigner/
programmer
databasedesigner/
programmer
applications
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Examples of systems
• COSA (demo)
• Staffware
• FLOWer
• …
Commercial Workflow Systems
1980 1985 1990 1995 2000
Exotica I - III
FlowMark MQSeries Workflow
jFlow
Staffware
Pavone
Onestone Domino Workflow
BEA PI
CARNOT
ViewStar
Digital Proc.Flo. AltaVista Proc.Flow
ActionWorkflow
SNI WorkParty
AdminFlow ChangengineWorkManager
OpenPM FlowJ et
Verve Versata
Action Coordinator
ActionWorks MetroDaVinci
FileNet WorkFlo Visual WorkFlo
FileNet Ensemble
Panagon WorkFlo
Xerox InConcert TIB/InConcert
Plexus FloWare BancTec FloWare
NCR ProcessIT
Netscape PM
MS2 Accelerate
Teamware Flow
Fujitsu iFlow
Beyond BeyondMail
DST AWD
IABG ProMInanD
DEC LinkWorks
COSA BaaN Ley COSA
Fujitsu Regatta
Pegasus
LEU
Banyan BeyondMail
Olivetti X_Workflow
Oracle WorkflowDigital Objectflow
ImagePlus FMS/FAF
VisualInfo
DST AWD
Continuum
Recognition Int.
WANGSIGMAEastman
WANG WorkfloweiStream
Lucent Mosaix
BlueCrossBlueShield
J CALS
iPlanet
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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-user’s view of Staffware, and
– show the need for analysis.
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WfMC reference model
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
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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).
register
checkA
checkB
pay
reject