CNIT 18000 Chapter Notes - Chapter 5: System Context Diagram, Data Dictionary, Business Logic
14 Nov 2016
School
Department
Course
Professor
Document Summary
A logical model shows what the system must do, regardless of how it will be implemented physically. Later in the systems design phase, a physical model is built that describes how the system will be constructed. Data and process modeling involves three main tools: data flow diagrams, data dictionary, process descriptions. 5. 2 overview of data and process modeling tools. A data flow diagrams (dfd) uses various symbols to show how the system transforms input data into useful information. During the systems analysis phase of the sdlc, the systems analyst creates a visual model of the information system using a set of data flow diagrams. A dfd shows how data moves through an information system but does not show program logic processing steps. A set of dfds provides a logical model that shows what the system does, not how it does it. Dfds use four basic symbols that represent process, data flows, data stores, and entities.
