Chap 5 - Systems Analysis and Design 8th Edition Chapter 5...

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Systems Analysis and Design 8th Edition Chapter 5 Data and Process Modeling
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Chapter Objectives Describe data and process modeling concepts and tools, including data flow diagrams, a data dictionary, and process descriptions Describe the symbols used in data flow diagrams and explain the rules for their use Draw data flow diagrams in a sequence, from general to specific Explain how to level and balance a set of 2
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Chapter Objectives Describe how a data dictionary is used and what it contains Use process description tools, including structured English, decision tables, and decision trees Describe the relationship between logical and physical models 3
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Introduction In Chapters 5 & 6, you will develop a logical model of the proposed system and document the system requirements Logical model shows what the system must do Physical model describes how the system will be constructed 4
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Overview of Data and Process Modeling Tools Systems analysts use many graphical techniques to describe an information system A data flow diagram (DFD) uses various symbols to show how the system transforms input data into useful information 5
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Data Flow Diagrams A data flow diagram (DFD) shows how data moves through an information system but does not show program logic or processing steps A set of DFDs provides a logical 6
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Data Flow Diagrams DFD Symbols 7
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Data Flow Diagrams DFD Symbols Process symbol Receives input data and produces output that has a different content, form, or both Contain the business logic, also called business rules Referred to as a black box 8
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Data Flow Diagrams DFD Symbols Data flow symbol Represents one or more data items The symbol for a data flow is a line with a single or double arrowhead Spontaneous generation Black hole Gray hole 9
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Data Flow Diagrams DFD Symbols Data store symbol Represent data that the system stores The physical characteristics of a data store are unimportant because you are concerned only with a logical model 10
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Data Flow Diagrams DFD Symbols Entity Symbol Name of the entity appears inside the symbol Terminators Source Sink 11
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Creating a Set of DFDs Create a graphical model of the information system based on your fact- finding results Three-step process Step 1: Draw a context diagram Step 2: Draw a diagram 0 DFD Step 3: Draw the lower-level diagrams 12
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Creating a Set of DFDs Guidelines for Drawing DFDs Draw the context diagram so that it fits on one
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This note was uploaded on 01/30/2012 for the course CNIT 180 taught by Professor Victorbarlow during the Spring '12 term at Purdue University-West Lafayette.

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Chap 5 - Systems Analysis and Design 8th Edition Chapter 5...

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