Dataflow Diagramming (DFD)

Dataflow Diagramming (DFD)

اسلاید 1: Dataflow Diagramming (DFD)Information systems viewed from a structured approach are composed of the following interrelated components:Procedures /processes with supporting logic specificationsData at restData in motionOutside sources and sinks of data flowEvents triggering processesRules for processing sequenceLife histories of data entities

اسلاید 2: Earlier Specification TechniquesSystem flowcharts: modelled all aspects

اسلاید 3: Earlier Specification TechniquesNarrativeEarlier techniques had disadvantages:Ambiguous Not a top down approach.LengthyNot understandable to userToo physicalNo Abstractiontry to describe all aspects of the system including control features and sequence

اسلاید 4: Requirements of DFD ModellingTo provide an abstract logical view of a systemUsesInvestigate the flow of data around a system to and from agents external to the systemto and from processes that transform the datainto and out of repositories of dataNo processing sequence specifiedPurposeto identify and clearly define the scope and boundary of the system an its various componentsto identify the requirements of the new systemto assist in the identification of events and functionsto facilitate in the communication between the analyst and the user