Rigorous Business Process Modeling with OCL

1
Rigorous Business Process Modeling with OCL

• Tsukasa Takemura
• (Software Development Laboratory,
• IBM Japan, Ltd.)
• Tetsuo Tamai
• (Graduate School of Arts and Sciences,
• The University of Tokyo, Japan)

2
Contents

• Introduction
• Research Issue
• Proposed Solution
• Business-IT Gap
• Business Process Modeling (BPM)
• Case Study
• OCL Extension for BPM
• Conclusion
• Further Improvements

3
Introduction

• Recently business process modeling (BPM) is
  getting a lot of attention as a predominant
  technology to bridge business-IT gaps.
• UML activity diagram was drastically changed in
  UML 2.0 to support business process modeling.

4
Research Issue

• However, this emerging technology is insufficient
  to bridge the business-IT gaps as expected
  because
• BPM is not so simple as business people expected
• BPMs dont provide enough information about
  activities behavior

5
Proposed Solution

• Rigorous BPMs help to bridge the business-IT gaps
  
• They propose
• To use OCL to describe business and to model
  business rigorously.
• An extension of OCL for BPMs
• To allow to specify an Action as a context of OCL
  expression and navigate to its input/output pins.
• To allow to use _at_pre keyword for input pin values
  of actions.

6
Business-IT Gap

• Enterprises must change their business processes
  in response to changes in their business
  enthronement to survive.
• Description about the business process provided
  by business persons tends to be ambiguous and
  does not provide IT persons with enough
  information to build/change IT systems rapidly
  according to changes in the business.

7
Business Process Modeling

• BPM is a method to model activities and their
  sequence, business objects passed among
  activities, resources, time and cost required to
  perform the activities.

8
Why BPM is not powerful enough?

• Ambiguity
• Many business consultants use presentation tools
  or drawing tools to depict business processes and
  they have no formal syntax or semantics.

9
UML as a BPM Tool

• A significant change in UML 2.0 Activity Diagram
• Its foundation was changed from state chart
  diagram to Petri-net.
• This change allows us to describe data flows and
  parallel execution of activities in UML 2.0
  activity diagrams.

10
UML as a BPM Tool

• It is still not sufficient because
• Behavior of each activity or action is not
  expressed in the activity diagrams.
• To implement the activities or the actions, their
  behaviors need to be expressed in the BPM.
• In some cases, business processes consist of
  asynchronous activities repeated with different
  intervals. It is difficult to model such
  processes only by connecting activities with
  control flows and object flows.
• We need to establish modeling methodology for
  such complicated asynchronously repeated
  processes.

11
Proposed solution

• Extended OCL

12
Case Study
13
Case Study

• Resource Plan (RP) Long term plan including
  productive facilities, allocation of human
  resources, etc.
• Production Plan (PP) Intermediate term plan
  including provision of long lead time materials.
• Master Production Schedule (MPS) Short term plan
  including provision of short time materials.
• The product is made of two types of materials
• Long Lead Time (LLT) material
• Short Lead Time (SLT) material

14
(No Transcript)
15
Case Study

• Planning Horizon Duration from start of
  execution of a plan to completion of it.
• Order Lead Time Duration from issue of an order
  to expected time of products/materials delivery.

16
Case Study

• CUSTOMERLEADTIME The shortest duration from
  receiving a customer order to product delivery
  associated to the order.
• LLTMATERIALLEADTIME The shortest duration from
  issuing a purchase order for the long lead time
  material to receiving the material.
• SLTMATERIALLEADTIME The shortest duration from
  issuing a purchase order for the short lead time
  material to receiving the material.

17
Case Study

• MPSHORIZON The duration from start of execution
  of a MPS to completion of execution of the MPS.
• PPHORIZON The duration from start of execution of
  a production plan to completion of execution of
  the production plan.
• RPSHORIZON The duration from start of execution
  of a resource plan to completion of execution of
  the resource plan.

18
Case Study

• Available To Promise (ATP) The amount of
  products available on a specific date including
  future.
• ATP Accumulated promised delivery -
  Accumulated products planned to be produced

19
Case Study
20
Case Study
21
(No Transcript)
22
OCL Expressions

• context AvailableToPromisegetQuantity( date
  Date ) Integer
• body
• existingPlans.getQuantity( date )
• - existingPromises.getQuantity( date )
• context ExistingPlangetQuantity( date Date )
  Integer
• body
• mpss-gtselect( executionCompleteDate lt date
  ).quantity-gtsum()
• productionPlans-gtselect( executionCompleteDate
  lt date and executionCompleteDate - TODAY() gt
  MPSHORIZON ).quantity-gtsum()
• resourcePlans-gtselect( executionCompleteDate lt
  date and executionCompleteDate - TODAY() gt
  PPHORIZON ).quantity-gtsum()

23
OCL Expressions

• context ExistingPromisegetQuantity( date Dime
  ) Integer
• body
• promisesForCustomerOrders-gtselect(
  estimatedDeliveryDate lt date and
• estimatedDeliveryDate - TODAY() gt
  CUSTOMERLEADTIME ).quantity-gtsum()
• context OrderPromisingpromiseOrder( )
• pre
• newCustomerOrder.expectedDeliveryDate gt TODAY()
  CUSTOMERLREADTIME and
• // Lead time of the new customer order is longer
  than CUSTOMERLREADTIME
• newPromisesForCustomerOrder-gtselect(ID
  newCustomerOrder.ID)-gtisEmpty()
• // no promise for the customer order exists

24
OCL Expressions

• post
• newPromisesForCustomerOrder-gtselect( ID
  newCustomerOrder.ID )-gtnotEmpty()
• // if there are any promise for the customer
  order
• implies
• newPromisesForCustomerOrder-gtselect( ID
  newCustomerOrder.ID )-gtsize() 1 and
• // there is only one promise for the customer
  order and newPromisesForCustomerOrder-gtselect( ID
  newCustomerOrder.ID ).quantity-gtsum()
• newCustomerOrder.quantity and
• // total quantity of promises is equal to
  requested quantity in customer order and
  newPromisesForCustomerOrder-gtselect( ID
  newCustomerOrder.ID )-gt
• forAll( estimatedDeliveryDate
  newCustomerOrder.expectedDeliveryDate ) and
• // estimated delivery date of the promise is
  equal to
• // expected delivery date of the customer order
  and
• newPromisesForCustomerOrder-gtselect( ID
  newCustomerOrder.ID )-gt
• forAll( quantity lt availableToPromise_at_pre.getQuan
  tity( estimatedDeliveryDate ))
• // total quantity of promises is equal to or less
  than ATP

25
Promise Order action with constraints in
activity diagram
26
OCL Extension for BPM

• OCL is useful for rigorous BPM. However, OCL is
  required to be extended to add the constraints
  described with OCL to UML activity diagrams.

27
OCL Extension for BPM

• Contexts
• To describe the behavior of actions, it is
  required to express preconditions and
  postconditions of actions.
• Consequently, OCL expression needs to have a
  context from which we can navigate to input pins
  and output pins of actions in order to express
  the constraint of the pins.
• (best context candidates --gt actions)

28
OCL Extension for BPM

• Contexts
• UML metamodel allows to add Constraint to
  Actions, however OCL specification does not
  expect to specify an action as a context.
• Chapter 7.3.4 of OCL specification
• The OCL expression can be part of Precondition
  or Postcondition, corresponding to
  ltltpreconditiongtgt and ltltpostconditiongtgt
  stereotypes of Constraint associated with an
  Operation of other behavioral feature. The
  contextual instance self then is an instance of
  the type which owns the operation or method as a
  feature.

29
OCL Extension for BPM

• Contexts
• Paper proposes (1) to extend OCL to allow to
• specify an Action as a context of OCL
• expression and navigate its input/output pins.

30
OCL Extension for BPM

• _at_pre
• Paper proposes (2) to extend the OCL to allow
• the use of _at_pre keyword to refer the value of
• an input object on arrival on an input pin.

31
Extended OCL Example

• context promiseOrder
• pre
• newCustomerOrderPin.expectedDeliveryDate gt
  TODAY() CUSTOMERLRADTIME and
• newPromisesForCustomerOrderPin-gtselect(id
  newCustomerOrderPin.ID ) -gtisEmpty()
• post
• newPromisesForCustomerOrderPin-gtselect( id
  newCustomerOrderPin.ID ) -gtnotEmpty()
• implies
• newPromisesForCustomerOrderPin-gtselect( id
  newCustomerOrderPin.ID_at_pre )
• -gtsize() 1 and
• newPromisesForCustomerOrderPin-gtselect( id
  newCustomerOrderPin.ID_at_pre ).quantity
• -gtsum() newCustomerOrderPin.quantity_at_pre and
• newPromisesForCustomerOrderPin-gtselect( id
  newCustomerOrderPin.ID_at_pre )-gt forAll(
  estimatedDeliveryDate newCustomerOrderPin.expect
  edDeliveryDate_at_pre ) and newPromisesForCustomerOrd
  erPin-gtselect( id newCustomerOrderPin.ID_at_pre
  )-gt forAll( quantity lt availableToPromise.quantit
  y_at_pre( estimatedDeliveryDate ) )

32
Conclusion

• Describing business environments rigorously helps
  rapid transition of a business process and its IT
  system. BPMs can help to bridge the Business-IT
  gaps.
• IT persons can use the preconditions and
  postconditions to implement the action in the
  business process on IT systems because the model
  describes what the action should and should not
  perform rigorously and formally.

33
Conclusion

• Authors proposed extension of OCL to support
  their approach. To describe constraints on
  actions in UML activity diagram, it is
  appropriate to specify an action as a context of
  OCL expression.

34
Further Improvements

• OCL is a powerful tool for business process
  modeling. But its syntax and semantics are still
  difficult to learn for business persons.
• To resolve this issue, the authors are planning
  to define domain specific languages to simplify
  OCL for business persons.