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Unformatted text preview: Process Modeling: Data Flow Diagrams EGA/ERLJ IE 154 Lecture 4 Objectives for Today Define Structured Systems Analysis(SSA) Know the different techniques of SSA Define Data Flow Diagrams (DFD) Draw the components of DFDs Know leveling concepts of DFDs Know the strategies of constructing DFDs Solve Examples 9-3 Models: Logical and Physical Logical model – a nontechnical pictorial representation that depicts what a system is or does. Synonyms or essential model , conceptual model , and business model . Physical model – a technical pictorial representation that depicts what a system is or does and how the system is implemented. Synonyms are implementation model and technical model . Model – a pictorial representation of reality. Just as a picture is worth a thousand words, most models are pictorial representations of reality. 9-4 Why Logical System Models Logical models remove biases that are the result of the way the system is currently implemented, or the way that any one person thinks the system might be implemented. Logical models reduce the risk of missing business requirements because we are too preoccupied with technical results. Logical models allow us to communicate with end-users in nontechnical or less technical languages. 9-5 Process Modeling and DFDs Process modeling – a technique used to organize and document a system’s processes. Flow of data through processes Logic Policies Procedures Data flow diagram (DFD) – a process model used to depict the flow of data through a system and the work or processing performed by the system. Synonyms are bubble chart, transformation graph, and process model. The DFD has also become a popular tool for business process redesign. 9-6 Simple Data Flow Diagram 9-7 Differences Between DFDs and Flowcharts Processes on DFDs can operate in parallel (at-the-same-time) Processes on flowcharts execute one at a time DFDs show the flow of data through a system Flowcharts show the flow of control (sequence and transfer of control) Processes on a DFD can have dramatically different timing (daily, weekly, on demand) Processes on flowcharts are part of a single program with consistent timing Data Flow Modeling Tools of Structured Systems Analysis Data Flow Diagrams Data Dictionary Transform Descriptions Decision Tree Decision Table Structured English DFD Principles...
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Into to Info Sys Lec 4 - Process Modeling: Data Flow...

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