1 CPN Workflow Models as Functional Requirements Jens Bæk Jørgensen Department of Computer Science University of Aarhus CPN05, Aarhus, October

2 Contents zThe Adviser Portal (AP) zExecutable Use Cases (EUCs) zBlanc loan advise EUC zEUCs in general zConclusions and outlook

3 The Adviser Portal (AP) zScope y15 Danish banks y15 software developers in three years zMain goals yIncreased efficiency yIncreased quality zAP provides a task list and must support yConcurrent tasks ySuspension and resumption of tasks yTransfer of tasks

4 Executable Use Cases (EUCs) - Resembles usual prototyping - Used to spur communication An EUC describes a work process that must be supported by a new computer system - Better name, perhaps: Executable Task Descriptions

5 Blanc loan advise EUC: background zBlanc loan ySimplest kind of loan yGranted without requiring the customer to provide security zImportant work process yBank advisers use about 50% of their time on credit- related tasks zBlanc loan advise EUC created by yBank data analysts yBank advisers (and their managers) yCPN consultants

6 Blanc loan advise EUC: informal tier z”The customer comes into the banks and says to his adviser that he wants to take a trip to Paris …” zMain advantage: Easily understandable zDrawback: Not executable

7 Blanc loan advise EUC: formal tier zA Coloured Petri Nets (CPN) model zMain advantage: Executable zDrawback: Not easily understandable

8 Blanc loan advise EUC: animation tier zConsistent with the formal tier: Shows the CPN model’s states and state transitions, but in another ”language” zCombines the main advantages of the informal tier and the formal tier yExecutable yUnderstandable

9 Blanc loan advise EUC: contributions zIncreased precision and detail yPrecise designations / dictionary yPrecise workflow descriptions yDetailed workflow descriptions zFacilitated cooperation between users and analysts yKeeping users focused yInvolve the users at the appropriate time

10 EUCs in general: properties zAdvantages yScenario management yPrecise and unambiguous specification yEasy and massive user involvement yLink user-level requirements with technical specifications of software zDrawbacks yMore difficult to change than informal descriptions; ”rapid prototyping” more difficult yTime-consuming yRequires special knowledge (CPN modelling and simulation) yRequires special tools (CPN Tools)

11 EUCs in general: related approaches zTraditional prototyping yRole-play with paper mock-ups yRole-play with high-fidelity prototypes zGraphical animation of formal models ySceneBeans [Kramer, McGee, Uchitel et al] yPlay-in/play-out [Harel et al]

12 EUCs in general: why use CPN? zCPN is our own favorite formal modelling language zCPN is well-suited to describe workflows zCPN scales well zCPN has adequate tool support zCPN’s extensive state concept facilitates the modelling of the environment

13 Conclusions and outlook: Bankdata project zIn early spring 2005, Bankdata analysts said they would like to continue using EUCs zWe tried to convince Bankdata management; have not suceeded yet zOutlook yFrom EUCs to implementations (CPNs -> BPEL4WS)

14 Conclusions and outlook: EUCs in general zEUCs are one among many approaches to requirements engineering zFormal methods difficult to sell zSubjects for further studies yCost-effectiveness yOther tier 2 languages than CPN yRelationship between EUCs and more traditional requirements specification artifacts yMaintainability of EUCs yScalability of EUCs

15 References: papers on Executable Use Cases zJørgensen, Bossen: Requirements Engineering for a Pervasive Health Care System, 11th Intl. Conf. on Requirements Engineering (RE), IEEE CS, 2003 zJørgensen, Bossen: Executable Use Cases: Requirements for a Pervasive Health Care System, IEEE Software, 2004 zJørgensen, Bossen: Executable Use Cases as Links Between Application Domain Requirements and Machine Specifications, 3rd Intl. Workshop on Scenarios and State Machines (at ICSE04), IEE, 2004 zBossen, Jørgensen: Context-descriptive Prototypes and Their Application to Medicine Administration, Intl. Conf. on Designing Interactive Systems (DIS), ACM, 2004 zJørgensen, Lassen: Aligning Work Processes and the Adviser Portal Bank System, 1st Intl. Workshop on Requirements Engineering for Business Need and IT Alignment (at RE05), 2005 zvan der Aalst, Jørgensen, Lassen: Let’s Go All the Way: From Requirements Via Colored Workflow Nets to a BPEL Implementation of a New Bank System, 13th Intl. Conf. on Cooperative Information Systems (CoopIS), Springer LNCS, 2005