Program, The University of Texas, Dallas

Modelling Enterprise

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) ❃ () 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? 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 Hardware Functions Functions Functions

loan evaluation warning oflowinventorylevel destroy confidentialinfo. loan requestdate+7days

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,,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 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

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