Modeling the Control-Flow Perspective. prof.dr.ir. Wil van der Aalst

Transcription

1 Modeling the ontrol-flow Perspective prof.dr.ir. Wil van der Aalst

2 From model to behavior...

3 asic concepts process instance, e.g., customer order, insurance claim, tax declaration, speeding ticket, etc. resource dimension resource an actor able to execute activities activity a concrete piece of work being executed, i.e., task+case+resource an abstract logical unit of work, e.g., "approve invoice" case case dimension work-item task process dimension a concrete piece of work, i.e., task+case

4 ases are handled in isolation (only compete for resources) resource dimension resource activity case case dimension work-item task process dimension

5 State: Photo of workflow resource dimension resource activity case case dimension work-item task process dimension

6 A workflow definition is composed out of three parts: 1.Process definition: a description of the process itself 2.Resource classification: a classification of the resources to be used 3.Resource management rules: how to map work onto resources

7 resource dimension Resource classification Resource management rules resource case case dimension activity work-item task Process definition process dimension

8 ase = Process Instance A case is the 'thing' which needs to be processed by following the process definition. (process instance, job, project) (insurance claim, purchase order, complaint, loan application) The state of a case is determined by: case variables (case parameters) The logistic attributes of a case which are used to route the case. conditions The requirements which are satisfied. (Application data) eyond the scope of the WFMS.

9 Straightjacketing behavior into cases having a life-cycle makes modeling easy record additional info c3 contact applicant c2 timeout start register c1 check completeness c4 AND split c5 check credit history c7 decide conditional c9 notify end c6 check financial data c8 c10 c11 determine rate c13 AND split communicate final decision c15 store offer c12 check property c14 c16 accept timeout PAGE 8

10 Example: What are the cases? Which lifecycle do we want to model? Orderline Order OrderID : OrderID 1 1..* OrderLineID : OrderLineID OrderID : OrderID ustomer : ustid Product : ProdID Amount : Euro NofItems : PosInt reated : DateTime TotalWeight : Weight Paid : DateTime Entered : DateTime ompleted : DateTime ackordered : DateTime Secured : DateTime DelID : DelID 1..* 0..1 Attempt DelID : DelID When : DateTime Successful : ool 0..* 1 Delivery DelID : DelID DelAddress : Address ontact : PhoneNo PAGE 9

11 Order:91245 Order instance ase id: Activity: create order Timestamp: :08.12 ustomer: John Amount: 100 ase id: Activity: pay order Timestamp: :13.45 ustomer: John Amount: 100 ase id: Activity: complete order Timestamp: :11.33 ustomer: John Amount: 100 OrderLine: Order OrderID : OrderID 1 1..* Orderline OrderLineID : OrderLineID OrderID : OrderID ase id: Activity: enter order line Timestamp: :08.13 OrderLineID: Product: iphone 4G NofItems: 1 TotalWeight: DellID: ase id: Activity: secure order line Timestamp: :08.55 OrderLineID: Product: iphone 4G NofItems: 1 TotalWeight: DellID: ustomer : ustid Product : ProdID OrderLine: Amount : Euro reated : DateTime Paid : DateTime ompleted : DateTime NofItems : PosInt TotalWeight : Weight Entered : DateTime ackordered : DateTime ase id: Activity: enter order line Timestamp: :08.14 OrderLineID: Product: ipod nano NofItems: 2 TotalWeight: DellID: ase id: Activity: create backorder Timestamp: :08.55 OrderLineID: Product: ipod nano NofItems: 2 TotalWeight: DellID: ase id: Activity: secure order line Timestamp: :09.06 OrderLineID: Product: ipod nano NofItems: 2 TotalWeight: DellID: Secured : DateTime DelID : DelID 1..* 0..1 OrderLine: ase id: Activity: enter order line Timestamp: :08.15 OrderLineID: Product: ipod classic NofItems: 1 TotalWeight: DellID: ase id: Activity: secure order line Timestamp: :10.06 OrderLineID: Product: ipod classic NofItems: 1 TotalWeight: DellID: Attempt DelID : DelID 0..* 1 Delivery DelID : DelID Delivery: When : DateTime DelAddress : Address Successful : ool ontact : PhoneNo Attempt: Attempt: Attempt: ase id: Activity: delivery attempt Timestamp: :08.55 DellID: Successful: false DelAddress: 5513VJ-22a ontact: ase id: Activity: delivery attempt Timestamp: :09.12 DellID: Successful: false DelAddress: 5513VJ-22a ontact: ase id: Activity: delivery attempt Timestamp: :08.56 DellID: Successful: true DelAddress: 5513VJ-22a ontact: Delivery: Attempt: ase id: Activity: delivery attempt Timestamp: :08.43 DellID: Successful: true DelAddress: 5513XG-45 ontact: PAGE 10

12 Orderline Orderline instance Order OrderID : OrderID ustomer : ustid Amount : Euro 1 1..* OrderLineID : OrderLineID OrderID : OrderID Product : ProdID NofItems : PosInt reated : DateTime TotalWeight : Weight Paid : DateTime Entered : DateTime ompleted : DateTime ackordered : DateTime Secured : DateTime DelID : DelID 1..* OrderLine: ase id: Activity: enter order line Timestamp: :08.13 OrderLineID: Product: iphone 4G NofItems: 1 TotalWeight: DellID: ase id: Activity: secure order line Timestamp: :08.55 OrderLineID: Product: iphone 4G NofItems: 1 TotalWeight: DellID: Attempt DelID : DelID When : DateTime Successful : ool 0..* Delivery DelID : DelID DelAddress : Address ontact : PhoneNo Order:91245 ase id: Activity: create order Timestamp: :08.12 ustomer: John Amount: 100 ase id: Activity: pay order Timestamp: :13.45 ustomer: John Amount: 100 ase id: Activity: complete order Timestamp: :11.33 ustomer: John Amount: 100 Delivery: Attempt: Attempt: Attempt: ase id: Activity: delivery attempt Timestamp: :08.55 DellID: Successful: false DelAddress: 5513VJ-22a ontact: ase id: Activity: delivery attempt Timestamp: :09.12 DellID: Successful: false DelAddress: 5513VJ-22a ontact: ase id: Activity: delivery attempt Timestamp: :08.56 DellID: Successful: true DelAddress: 5513VJ-22a ontact: PAGE 11

13 Mapping a process definition onto a Petri net (describing the lifecycle of a single instance) task condition case subprocess case variables

14 MS Workflow Foundation Global 360 PM Suite YAWL FileNet Inoncert jpm casewise UML ADs PMN izagi Axxerion IM WebSphere record additional XPDL timeout info c3 contact applicant c2 OSA start EPs TeamWARE Promatis c5 check credit c7 history register c1 check c4 AND split decide c9 notify Petri completeness nets as a tool-independent conditional AND split PM one c6 check c8 representation financial data determine c13 Protos rate c11 communicate final decision c16 c12 check c14 Flowonnect property c15 accept c10 store offer timeout end PEL SAP Workflow Flower Flowmark Global 360 Wise Ensemble izzdesigner

15 asic routing patterns Sequential "first A then " (Sequence pattern) Parallel "A en at the same time or in any order" AND-split (Parallel split pattern) AND-join (Synchronization pattern) hoice "A or " XOR-split (Exclusive choice pattern) XOR-join (Simple merge pattern) Iteration "multiple A's" (Structured loop pattern)

16 Sequence pattern A "First A then "

17 Parallel split pattern A AND-split "After A both and "

18 Synchronization pattern D AND-join "Task D after both and have completed"

19 Parallel routing A D

20 Exclusive choice pattern do A XOR-split do "After A do or "

21 Simple merge pattern XOR-join D "D after or "

22 Alternative routing do A D do Two questions: 1. Why asymmetric? 2. How to choose between and?

23 Asymmetry do A D do done A D done

24 Syntactic sugar (splits) A A AND-split do A A XOR-split do

25 Syntactic sugar (joins) D D AND-join done D D done XOR-join

26 Notation A D A D

27 Structured loop pattern A X while variant

28 Loops (2) A Y repeat variant

29 Loops (3) A A X Y X A Y combination variant

30 Role of data Data can be at different levels, e.g., the scope can be at the process level, case level, task level, etc. We assume data to be at the case level. A

31 A

32 How to choose? age>18 A age 18

33 Exercise A travel agency organizes trips. To organize a trip the following tasks are executed. First the customer request is registered, then an employee searches for opportunities which are communicated to the customer. Then the customer is contacted to find out whether (s)he is still interested and whether more alternatives are desired. If the customer selects a trip, then the trip is booked. In parallel (if desired) one or two types of insurance are prepared. Two weeks before the start date the documents are sent to the customer. It is possible that the customer cancels the trip at any time before the start date.

34 Triggers The workflow system cannot force things to happen in reality: The arrival of an electronic message (EDI) which is needed to execute a task. A resource which starts to work on a case. The arrival of a paper document. A phone call to confirm a purchase order. A workflow system is a reactive system, i.e. it is triggered by the environment. Some tasks require a trigger.

35 We identify four kinds of tasks: Automatic No trigger is required. User A resource takes the initiative. External A external event (message, phone call) is required. Time The task requires a time trigger.

36 The triggering concept can be modeled explicitly... environment puts token in trigger place However, we will omit the extra place.

37 In case of two triggers Semantics of multiple triggers: all are needed.

38 Example showing some triggers contact_ cust start register c2 search c 3 communicate c4 end c15 cancel c 5 book c 8 start_ trip AND_ c 6 insurance1? c 9 insurance1 c 11 split AND_join c 13 send_documents c 14 c 7 insurance2? c 10 insurance2 c 12 PAGE 37

39 There is a subtle but important distinction between the following terms: task A logical step which may be executed for many cases. work item = task + case A logical step which may be executed for a specific case. activity = task + case + (resource) + (trigger) The actual execution of a task for a specific case. case dimension resource dimension resource case activity work-item task process dimension Work items and activities are task instances.

40 A process definition A (sub)process has one input and one output place.

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42 Example: Application for mortgage onsider the application process for a mortgage of some bank. A mortgage is a loan for buying e.g. a house. The bank has two departments relevant for this process: finance and customer relations. The process start by registering the request for a mortgage by an employee of the customer relations department. Then the process is checked for completeness by an employee of the same department. If the information is incomplete, the applicant is contacted by the same employee. If the applicant sends this information within two weeks, the additional information is added by an employee of the customer relations department. If not, the process ends because of insufficient information.

43 ont'd When all information required is present, two checks are conducted (in any order). The credit history is checked by an employee of the customer relations department and the financial data is checked by an employee of the finance department. ased on these two checks, a manager of the customer relations department makes a conditional decision. If the conditional decision is negative, the customer is notified by an employee and the process ends. If the conditional decision is positive, the interest rate is determined and the property is checked. oth tasks can be done in any order and need to be done by experts of the customer relations department.

44 ont'd After these two tasks, a final decision is made when a manager of the customer relations department has a meeting with the applicant. The final decision may be that no agreement can be reached and, hence, the process ends. It can also be that during the meeting there is consensus on the conditions and the offer is subsequently stored in the information system of the bank. Moreover, it may also be the case that no immediate consensus can be reached but that the customer does not decline the offer immediately. In the later case, the applicant has one week to indicate that she will take the offer anyway. If there is no response within a week, the process ends. If there is a response in one week, the offer is stored in the information system of the bank.

45 ont'd Model the above workflow process using the notation of the book, i.e., a process definition (i.e., WF-net including triggers). Make sure that your process definition is sound, i.e., it is always possible to end properly (token in final place) and there are no dead parts/dangling tokens. Test the process model using some typical scenarios to make sure that it is always possible to terminate properly!

46 record additional info c3 contact applicant c2 timeout start register c1 check completeness c4 AND split c5 check credit history c7 decide conditional c9 notify end c6 check financial data c8 c10 c11 determine rate c13 AND split communicate final decision c15 store offer c12 check property c14 c16 accept timeout

47 Exercises, see OASE "PMS-instruction-2-control-flow-questions.ppt/pdf" PAGE 46