ISBN : 978-81-963532-2-3 (E-Book) existing system, where the basic primitives can be used in the newer system. Both, top-down and bottom-up approaches are not practical individually. Instead, a good combination of both is used. SOFTWARE ANALYSIS & DESIGN TOOLS Software analysis and design includes all activities, which help the transformation of requirement specification into implementation. Requirement specifications specify all functional and non-functional expectations from the software. These requirement specifications come in the shape of human readable and understandable documents, to which a computer has nothing to do. Software analysis and design is the intermediate stage, which helps human-readable requirements to be transformed into actual code. Let us see few analysis and design tools used by software designers: Data Flow Diagram Data flow diagram is a graphical representation of data flow in an information system. It is capable of depicting incoming data flow, outgoing data flow and stored data. The DFD does not mention anything about how data flows through the system. There is a prominent difference between DFD and Flowchart. The flowchart depicts flow of control in program modules. DFDs depict flow of data in the system at various levels. DFD does not contain any control or branch elements. Types of DFD Data Flow Diagrams are either Logical or Physical. • Logical DFD - This type of DFD concentrates on the system process and flow of data in the system. For example in a Banking software system, how data is moved between different entities. 43 Software Engineering Keerthana P, Manasa KN, Ganga D Bengal
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