flexible workflow management approaches [kompatibilitätsmodus] · 2010. 4. 7. · id i i i i l i l...

Flexible Workflow Management ApproachesManagement Approaches

Flexible Workflow Management Approaches

Matthias Voigt

Agenda

Motivation – What is Flexibility?Fl ibl W kfl M t A hFlexible Workflow Management Approaches

Exception HandlingLate ModellingLate ModellingLate BindingCase Handlingg

Conclusion

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Matthias Voigt

Motivation

Workflow management systems are usually designed to supportsupport

Highly standardized processesStructurally robust processesStructurally robust processesFrequently executed processes

Typical companies using WfMSInsurancesCredit institutions(Public) Administration

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Matthias Voigt

Motivation

(Not so) new requirements to WfMSBusiness processes have to become more and more flexibleI.e. they are changing more or less rapidlySupport of „Flexible“, „creative“ and „skill-intensive“ industries

Support through „classical“ WfM approaches not availableavailable

New WfM approaches have to considerNew WfM approaches have to considerChanging business processesUnforeseen events that „disturb“ running workflows„ g

i.e. they have to be „flexible“

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Flexibility TechniquesException HandlingException Handling

Exceptions (= harmful events usually not modelled in a workflow) are anticipated…… and modelled in a general way

Late ModellingW kfl t i bl k bWorkflows contain black boxesBlack boxes are filled with workflow model at run-time,depending on the particular situationp g p

Late BindingWorkflow models are not compiled but interpretedChanges of the workflow model are possible at run-time

Case HandlingWorkflows are not dependent on control flowWorkflows are executed as soon as all required data are available

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Matthias Voigt

Nurcan (2008)

Agenda



Conclusion

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Matthias Voigt

Exception Handling

Anticipation of events that „disturb“ the execution of workflowsworkflows

account not coveredapplication system not availableapplication system not availabledeadline exceeded

Alternativesmodelling any possible exception as a part of the workflow modelmodelling exceptions as patterns (in all 135 patterns)

Approach of RUSSEL, VAN DER AALST, and TER HOFSTEDE (2006):“W kfl E ti P tt ”“Workflow Exception Patterns”

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Matthias Voigt

Exemplary Workflow (YAWL)

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Russell et al. (2006)

Workflow Exception Patterns

Exception Typeswork item failured dli i tideadline expirationresources not availableexternal eventexternal eventconstraint violation

Exception Handling strategiesp g gat Work Item Level (only an excerpt; total of 15)

force-complete (SFC)reallocate (ARA)

at Case Levelcontinue current workflow instancecontinue current workflow instancecancel current workflow instancecancel any instance of the current workflow type

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Workflow Exception Patterns

Recovery actionno actionno actionrollbackcompensatecompensate

Workflow exception handling languagep g g gset of modelling elementsintegration in workflow models

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Exception Handling Elements

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Example 1: Work Item Failure (Task)

Activity „check credit“ fails

Exception handling pattern:

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Matthias Voigt


Example 2: Deadline Expiration (Task)

Deadline of activity „pick order“ expires


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Example 3: Resources not Available (Process)

Resources of an arbitrary task are not available


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Example 4: External Event (Process)

Client account is frozen


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Example 5: Constraint Violation (Task)

Constraint „order_value < (client_credit_limit + client account balance)“ of task accept order“ isclient_account_balance) of task „accept order is violated


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Workflow Model with Exception Patterns

Layer 2: Exception Handling Definition

C

Work Item Failure

Deadline Expiration

Constraint Violation

Layer 1: Workflow Definition

Accept order

Check credit

Print Pick order

Organise shipping

Createinvoice

Processorder

Update client

Completeorder

order list Pick order account

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Agenda



Conclusion

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Late Modelling

Workflow models that consist ofstructured parts („classic“ workflow models)

i t t d tsemi-structured parts

Workflows contain black boxesWorkflows contain black boxesBlack boxes are filled with workflow model at run-time,depending on the particular situationdepending on the particular situationContents of the black boxes cannot be anticipatedModeller is alerted as soon as late modelling becomesModeller is alerted as soon as late modelling becomes necessary

Approach of Hagemeyer J, Herrmann T, Just K, Striemer R. pp g y , , ,(1997): Flexibilität bei Workflow-Management-Systemen

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Late Modelling

Process of publishing a book with „black box“

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Hagemeyer et al. (1997)

Late Modelling

Business process section „delivery date query“

Check inventory Inventory sufficientInventory not

sufficient

Determine components

C t Check capacityComponents determined

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Matthias Voigt

Hagemeyer et al. (1997)

Pockets of Flexibility

Pocket of Flexibilityy

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Matthias Voigt

Sadiq et al. (2001)

Agenda



Conclusion

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Matthias Voigt

Late Binding

Late BindingWorkflo models are not compiled b t interpretedWorkflow models are not compiled but interpretedChanges of the workflow model are possible at run-time

Approach of WESKE, HÜNDLING, KUROPKA, and SCHUSCHEL(1998): Objektorientierter Entwurf eines flexiblen Workflow-(1998): Objektorientierter Entwurf eines flexiblen WorkflowManagement-Systems

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Weske et al. (1997)

Workflows in WASA21input 1

e2e1input

parameters a2a1 output

parameters

Workflowc2c1

control flowparameters

start conditionparameters

workflow typesworkflow typescomplex workflowatomic workflow

complexworkflow

atomicmanual workflowautomatic workflow

atomicworkflow

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Matthias Voigt

Weske et al. (1997)

Exemplary Workfloworder PL PL ll t

checkinventory

removeproduct

from stockorder

order PL PL pallet

pallet

c1 c1

check order

prepareinvoice

ship productorder invoice

invoicepallet

1c2c1 &

invoicec1

check inventoryorder PL

AA

c1create

product listallocateproducts

order PrL PrL ANA

AA

c1c2c1

orderproducts

createpicking list.

ANA

ANA

ANA ANA PL

c1 p

(is_empty(ANA) AND c1 AND NOT c2)OR (NOT is_empty(ANA) AND c1 AND c2)

c1 AND NOT is_empty(ANA)

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Matthias Voigt

Weske et al. (1997)

Structural Equivalence of Schema and Instances

W1

x

W2

x y

cW3

y

cSchema

Execution

x=1 x=1 y=5 y=5

W1‘ W2‘c=true

W3‘c=true

x=4 x=4 y=8 y=8

Instances W1‘‘ W2‘‘c=true

W3‘‘c=true

x=9 x=9 y=2 y=2

W1‘‘‘ W2‘‘‘

y

c=trueW3‘‘‘

y

c=true

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Matthias Voigt

Weske et al. (1997)

Interpretive Approach

Workflow schemas are interpreted at run-time( Late Binding)( Late Binding)

Workflow schemas are not compiledNo separation of run-time und build-time.p

AdvantageAdvantageModification of running workflow instances is possibleRunning workflow instances can be adapted to new schemas

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Matthias Voigt

Weske et al. (1997)

Adapting Running Instances

KL Pal

OrderCheck

availability

Order KL

c1

Pick productc1

Take order

Order Inv InvPal

Create invoicec1

Ship packagec2c1 &

COMPLETED ONWORKLIST RUNNINGNOT YETSTARTEDLegend

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Matthias Voigt

Weske et al. (1997)


KL Pal

OrderCheck

availability

Order KL

c1

Pick productc1

Take order

Order Inv InvPal

InvPal

InvPal

Create invoicec1

Ship packagec1

Quality checkc2c1 &

Modification of the workflow schemaDeletion of old edges, parameters and conditionsInsertion of new workflowInsertion of new edges, parameters and conditions

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Matthias Voigt

Weske et al. (1997)


A tik l

KL PalKL Pal

OrderCheck

availability

Order KL

c1

Artikelauslagernc1

Pick productc1

Take order

Auftr Rech RechPal

RechPal

RechPal

Auftr RechOrder Inv RechPal

RechPal

RechPal

RechPal

InvPal

InvPal

RechPal

RechPalInvPal

Rechnungerstellenc1

Paketversendenc1

Qualitätprüfenc2

c1 &Rechnungerstellenc1Create invoice

c1Qualitätprüfenc2

c1 & Qualitätprüfenc2c1 & Quality checkc2c1 & Paketversendenc1

Paketversendenc1

Ship packagec1

C ti i tiContinuing execution…

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Matthias Voigt

Weske et al. (1997)

Automatic Adaption of Running Instances to new Schemas

Workflow schema is modified

The WfMSh k hi h i t f th h tl ichecks which instances of the schema are currently running

performs a consistency check is modification possibleadapts instances to new schemaadapts instances to new schema

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Matthias Voigt

Weske et al. (1997)

Example: Automatic Adaptionold workflow schema new workflow schema

W1 W2 W3 W1W2Manual

changethrough

W4 W5user

old workflow instance new workflow instance

W1 W2 W3 W1W2

AutomaticchangethroughWfMS

W4 W5WfMS

W2Automatic

changeW1 W2 W3 W1

W2

W4 W5

changethroughWfMS

W1 W2 W3 not possibleAutomatic

changethroughWfMS

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Matthias Voigt

Weske et al. (1997)

Agenda



Conclusion

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Case Handling

Case HandlingWorkflo s are not dependent on control floWorkflows are not dependent on control flowWorkflows are executed as soon as all required data are available

Approach of SCHUSCHEL and WESKE

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Case HandlingCl i “ kfl d l„Classic“ workflow model

A2Analyse customer

D1 Cu

stome

r data D2 Customer rating

A1 A3D0Offer

D ing

D1 Customer dataD6 OfferTake order Create offerOfferrequest

D5 Bill of

D6 Offer

A5Calculation

A4Technical

D5 Bill of material

Calculationsolution

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Matthias Voigt

Schuschel, Weske (2002)

Case Handling

Id I i i i l i l d dIdea: In most cases activities are exclusively dependent on their input data

R l f t l fl Removal of control flows

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Schuschel, Weske (2002)

Case Handling

Why is this more flexible?

Data objects can be created by other instances than the workflow model prescribesmodel prescribes

If they already exist, depending activities can start earliery y , p g

Some activities may be left out

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Matthias Voigt

Agenda



Conclusion

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Matthias Voigt

Conclusion

What are benefits and limitations of the approaches shown?

Exception HandlingLate ModellingLate BindingLate BindingCase Handling

Discussion

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Matthias Voigt

Flexible Workflow Management ApproachesManagement Approaches


Matthias Voigt

flexible workflow management approaches [kompatibilitätsmodus] · 2010. 4. 7. · id i i i i l i l...

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