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PEMODELAN SISTEM

PEMODELAN SISTEM. Process Modeling Data Modeling. Data and Process Modeling. During systems development both processes and data must be modeled Data modeling describes data used by system Process modeling describes processes carried out by system Level of detail

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PEMODELAN SISTEM

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  1. PEMODELAN SISTEM • Process Modeling • Data Modeling

  2. Data and Process Modeling • During systems development both processes and data must be modeled • Data modeling describes data used by system • Process modeling describes processes carried out by system • Level of detail • Varies between highest summary and lowest detail • Structured tools enable level of detail to be varied

  3. Process Modelling

  4. Data Flow Diagrams (DFDs) • Graphic representation of a system that uses a small number of symbol shapes to illustrate how data flows through interconnected processes • Most natural way to document processes • Emphasis on processes rather than data B-4

  5. DFD Symbols • DFDs consist of four symbols 1) Environmental elements called terminators • Person • Organization • Another system 2) Processes which transform inputs to outputs • Labeled with verb and object • Also labeled with system or computer program name B-5

  6. DFD Symbols [cont.] • DFD symbols [cont.] • Data flows which consist of logically related data elements that travel from one point or process to another. In other words, data in motion. • Structures • Diverge • Converge • Data stores which are data repositories. In other words, data at rest. B-6

  7. LDFD and PDFD • DFD dikelompokkan menjadi 2: • Logical DFD • Fokus pada bisnis dan bagaimana bisnis berjalan • How the system will be constructed • Physical DFD • How the system will be implemented • Include hardware, software, files, people yang terlibat dalam sistem

  8. Mail A Data Flow Diagram (Figure 0 Diagram) of a Sales Commission System Customer 1. Open mail Sales orders Entered sales orders 2. Enter sales order data Sales order form file Entered sales order data 3. Sort sales order s Sorted sales records Sales commission report Sales manager 4. Compute sales commissions B-8

  9. When Drawing a Context Diagram • Use only a single process symbol • Label the process symbol to represent the entire system • Do not number the single process symbol • Include all terminators for the system • Show all the data flows between the terminators and the system B-9

  10. A Context Diagram of a Sales Commission System Mail Customer Sales Commission System Sales commission report Sales Manager B-10

  11. Figure n Diagrams • Documents a single process of a DFD in a greater amount of detail • n represents the number of the process on the next higher level that is being documented • The term “leveled DFDs” describe the hierarchy of diagrams ranging from context to the lowest-level figure n diagram B-11

  12. Figure 4 Diagram of a Sales Commission System Sorted sales records 3 4.1 Compute commission amounts Sales commission report 4.2 Accumulate totals Sales manager Commission amounts B-12

  13. How Many Levels to Use? • Restrict a single DFD to no more than six to eight processes • Use another tool to document the lowest level of detail but use no more than a single page. B-13

  14. Data Flow Diagramming Guidelines • Label each data flow with a unique name. • Keep data flow names constant between levels. • Show proper disposition of records deleted from a data store. • When documenting a computer program, do not include reads/writes. • Avoid read-only processes. • Write-only processes are permissible when time serves as the trigger. B-14

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