Computer Science Program, The University of Texas, Dallas Modelling Enterprise Requirements Why Enterprise Modelling? Traditional Approaches to Enterprise Modelling SADT IDEF0 Lawrence Chung Why EnterpriseModelling? "... Requirementsdefinitionisacarefulassessmentof the needsthatasystemistofulfill. It mustsaywhyasystemisneeded, based oncurrentandforeseenconditions, which maybeinternaloperationsoranexternalmarket It mustsaywhatsystemfeatureswillserveandsatisfythiscontext. And itmustsayhowthesystemistobeconstructed..." [Ross77] ❃ Enterprise requirements for "contextanalysis"-thereasonswhysystemistobecreated. (e..g, whyISforBPR,organizationalstructure,agents,goals) constraints ontheenvironmentinwhichsystemistofunction (e..g, airplanerunningbeyondrunway,AT&TInternetservice) the meaningofsystemrequirements (symbols, relationships,ontology,vocabulary) ❃ (System) functional requirements a descriptionofwhatthesystemistodo; what informationneedstobemaintained? what needstobeprocesses? {f: I -> O} ❃ (System) non-functional requirements (global) constraintsonhowthesystemistobeconstructedandfunction. E.g., -ilitiesand-ities {bcfh(f: I -> O)} Lawrence Chung Why EnterpriseModelling? c Order Processing loan request Buyer Dealer order Customer Support Invoice Factory Shipment Order Processing Transportation initial payment Accounting Financing (Loan Officer) yes/no/more info, rate, period Person power: several hundreds Processing time: long enough to invite complaints Errors: annoying and significant Why shouldasystembecreated? goals/objectives Whose workwouldthesystemsupport? agents, activities/operations How wouldtheinfo.insystemhelprunenterprise? information flow What's theroleofsystemforcross-functionalactivities? workflow Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c Background d trademark ofSoftech,Inc.(Ross) d in usesincethemid-seventies d inspiration formanycommericaltools(DFD?) c View d "System" referestoanyenterprise/organization,physical,manufacturing, and swsystem => systemFRs!CourseProject c Context Analysisshouldinvolve d technical assessment:feasibilityofsystemarchitecture Are thecomponentsandinter-relationshipstechnicallyrealizable? d operational assessment:systemperformanceinaworkingenvironment Can thesystemperformtaskXinlessthanaweekoftime? d economic assessment:costs&impactsofsystemimplementationuse Can thesystembebuiltwith$20M,1000SEeers,in2yrs? Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c Requirements definition encompasses allaspectsofsystemdevelopmentpriortoactualdesign Current orForeseenConditions similar customerbase similar dealerships+ similar interestrates order processingmax.1week Management Objectives error rate0.1% low factoryinventorylevel Operational Concepts Define system functions and allocate Personal Software Hardware Functions Functions Functions loan evaluation warning oflowinventorylevel destroy confidentialinfo. loan requestdate+7days<now.date Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c SADT Primitives Diagrammatic! Control Input Label Output Mechanism e Boxes "composed"intoadiagramandinterconnectedthrougharrows e Each diagramisdecomposedintoupto"six"otherdiagrams e Informal documentation(aswithDFDs) e Two typesofdiagrams h Actigrams boxes: happenings-activities,operations,processing,events box label:startwithaverb h Datagrams boxes: things-entities,objects,data,information,substances box label:noun Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c SADT Primitives Diagrammatic! Control Input Label Output A326 3 Mechanism e Box annotation:representsatraceofstepwiserefinement/decomposition h Actigrams start withanA,suffixitdecompositionsequence h Datagrams e Box number:optional,usuallylevelofnesting e Semantics ofArrows h In an actigram j Inputs aredatathatconsumedbytheactivity j Outputs areproducedbytheactivity j Controls influencetheexecutionofanactivitybutarenotconsumed j Mechanism isaprocessor(machine,computer,person)which makes theactivityhappen Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c Example: ModellingSoftwareProcessforthedevelopmentworld Controls influencetheexecutionofanactivitybutarenotconsumed Design Requirements Inputs aredatathatconsumedbytheactivity Perform Detailed Recommended DetailedData Design Preliminary DesignData A0 3 Outputs areproducedbytheactivity Design Engineer Mechanism isaprocessor(machine,computer,person)which makes theactivityhappen Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c Example: ModellingSoftwareProcessforthedevelopmentworld Design Requirements Separate PA Data Structure Preliminary From Perform Design Data Algorithm 1 PDS Data Structure Design Perform 2 DS Algorithm Design Recommended 3 Detailed Design A0 1 Design Engineer Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c Example: ModellingSoftwareProcessforthedevelopmentworld Design Requirements Separate PA Data Structure Preliminary From Perform Design Data Algorithm 1 PDS Data Structure Design Perform 2 Algorithm DS Design Recommended 3 Detailed Design A0 1 Design Engineer Design Requirements ? PA Handle Normal DD forNormal DS Cases 1 Handle ? Exc. Recommended 2 Detailed Design ? A3 2 A32 3 Design Engineer ? Lawrence Chung Traditional ApproachestoEnterpriseModelling SADT (StructuredAnalysisandDesignTechnique) c SADT Primitives Diagrammatic! Control Input Label Output D23 3 Mechanism e Semantics ofArrows h In an actigram j Inputs aredatathatconsumedbytheactivity j Outputs areproducedbytheactivity j Controls influencetheexecutionofanactivitybutarenotconsumed j Mechanism isaprocessor(machine,computer,person)which makes theactivityhappen h In a datagram j Inputs areactivitiesthatproducethedata j Outputs consumethedata j Controls influencetheinternalstateofdata j Mechanism isadeviceforstorage,representation,impl.,etc. Modify status Preliminary Perform Design Perform Preliminary Data Detailed Design Design D0 0 Repository disk Lawrence Chung Traditional ApproachestoEnterpriseModelling IDEF0 (IntegrationDefinitionforFunctionModelling) c Background e released inDec.,1993 e the "referencemodel"forsystem/enterprisefunctionmodelling e also inuseforsoftwareprocessmodelling e Federal InformationProcessingStandard e maintained byDept.ofCommerce, NIST (NationalInstituteofStandardsandTechnology)& Computer SystemsLaboratory e based onICAM(IntegratedComputer-AidedManufacturing) from theUSAirForceWrightAeronauticalLaboratories e supported byComposerforenterprisemodelling e closely resembles"actigrams"ofSADT e Information Modelling(IDEF1X)usesERD+generalization/specialization h Stringent rules E.g., Boxesshallbesufficienttoinsertboxnames rectangular inshapewithsquarecorners drawn withsolidlines Arrows thatbendshallbecurvedusingonly90degreearcs shall bedrawninsolidlineseqments vertically orhorizontally,notdiagonally Lawrence Chung Traditional ApproachestoEnterpriseModelling IDEF0 (IntegrationDefinitionforFunctionModelling) c ICOM codes(variationsofarrows) E.g., tunneledarrows:provideinformationataspecificlevelofdecomposition that isnotrequiredforunderstandingatsomeotherlevels e I1, O1, C1, M1 are not shown on child diagram C1 ( ( ( C1 ( C1 ( ( ( ( C1 e I1, O1, C1, M1 are not shown on parent diagram C1 ( ( ( ( C1 C1 ( ( ( ( C1 Lawrence Chung Traditional ApproachestoEnterpriseModelling IDEF0 (IntegrationDefinitionforFunctionModelling) c Diagram syntaxrules E.g., e control feedbacks shall be shown as "up and over" 1 2 e input feedbacks shall be shown as "down and under" 1 2 e mechanism feedbacks shall be shown as "down and under" 1 2 Lawrence Chung Traditional ApproachestoEnterpriseModelling Deficiencies Diagrammatic! Control Input Label Output Mechanism e Ambiguities h Informal documentation(aswithDFDs) h Boxes insideaboxmayrepresentspecializations,instances,aggregations h temporal relationshipsnotclear When areinputsproduced? as achunkorinpiece-mealmanner When areoutputsproduced? on receivinginputs,anytimeafterwards,instantaneously How areactivitiesrelated? sequential, concurrent,overlap,during h cardinality, mandatory/optional h attributes ofdata h constraints onarrows SADT/IDEF0 forahigh-levelsystemfunctionalmodel Lawrence Chung.