IS 460 Notes
10
IS 460 Notes IS 460 Notes Documenting a System Analysis Documenting a System Analysis with Dataflow Diagrams with Dataflow Diagrams By By Thomas Hilton Thomas Hilton
description
IS 460 Notes. Documenting a System Analysis with Dataflow Diagrams By Thomas Hilton. System Analysis. The foundation skill of IS Professionals Understanding Whole Systems via the Systems View Outputs Information Other Inputs Data Other Processes Hardware Software People Procedures - PowerPoint PPT Presentation
Transcript of IS 460 Notes
IS 460 NotesIS 460 Notes
Documenting a System Analysis Documenting a System Analysis with Dataflow Diagramswith Dataflow Diagrams
ByBy
Thomas HiltonThomas Hilton
System AnalysisSystem Analysis
The foundation skill of IS ProfessionalsThe foundation skill of IS Professionals Understanding Whole Systems via the Systems ViewUnderstanding Whole Systems via the Systems View
OutputsOutputs InformationInformation OtherOther
InputsInputs DataData OtherOther
ProcessesProcesses HardwareHardware SoftwareSoftware PeoplePeople ProceduresProcedures
User Perspective!User Perspective!
Systems are ComplexSystems are Complex
They Can Only be Understood by They Can Only be Understood by “Functional Decomposition”“Functional Decomposition”
Invoke the System-Supersystem-Invoke the System-Supersystem-Subsystem viewSubsystem view
Alternate between the Black Box Alternate between the Black Box Concept and the Closed System Concept and the Closed System ConceptConcept
Create Successive Levels of DetailCreate Successive Levels of Detail
Information Systems Information Systems ComponentsComponents
Entities External to the SystemEntities External to the System ““Data” that Flows Through the Data” that Flows Through the
SystemSystem Processes that Receive and Produce Processes that Receive and Produce
DataData ““Data Stores” that store dataData Stores” that store data
Information Systems Information Systems ComponentsComponents
External Entity . . . . . . . . . .External Entity . . . . . . . . . .
Dataflow . . . . . . . . . . . . . .Dataflow . . . . . . . . . . . . . .
Process . . . . . . . . . . . . . . .Process . . . . . . . . . . . . . . .
Datastore . . . . . . . . . . . . .Datastore . . . . . . . . . . . . .
Process name
x.x
Data Store NameDx
Entity Name
Data Flow Name
Levels of DetailLevels of Detail
Context LevelContext Level Level 0Level 0 Levels 1, 2, etc.Levels 1, 2, etc. Functional Primitive LevelFunctional Primitive Level
Processes ExplodeProcesses Explode
Each process at a higher level Each process at a higher level corresponds to a set of processes at corresponds to a set of processes at the next lower levelthe next lower level
x.x x.xx.x
x.x x.x
x.x
x.x x.x
x.x x.x
x.x
x.x
Entity Name
Entity Name
x.x
Some Traits of the ExampleSome Traits of the Example
Every dataflow starts somewhere and Every dataflow starts somewhere and ends somewhereends somewhere
Dataflows at a lower level agree with the Dataflows at a lower level agree with the dataflows of their parent processdataflows of their parent process
No dataflow exits and enters the same No dataflow exits and enters the same processprocess
Every process has at least one input and Every process has at least one input and at least one outputat least one output
Every process explodes to at least two Every process explodes to at least two subprocessessubprocesses
Some processes don’t explode; these are Some processes don’t explode; these are called functional primitives, and they called functional primitives, and they contain pseudocodecontain pseudocode
Pseudocode, the Right Pseudocode, the Right Idea…Idea…
Pseudo = fake, falsePseudo = fake, false Code = software instructionsCode = software instructions
Select NAME, ADDRESSSelect NAME, ADDRESSFrom TABLEFrom TABLEWhere CREDIT_LIMIT .GE. 10000Where CREDIT_LIMIT .GE. 10000
Fake variable names
Fake table name
Fake condition
s
Incorrect syntax
Questions?Questions?
On to an Example!
