(a). The information domain of a problem must be represented and understood, (b)
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(a). The information domain of a problem must be represented and understood, (b). Models that depict system information, function, and behavior should be developed, (c). The models (and the problem) must be hierarchically partitioned, (d). The analysis process should move from essential information towards implementation detail. Using these principles show how structure analysis (SA) accomplishes each fundamentals. (Hints: Show how DFD's, CFD's, PSPEC's, CSPEC's, and Requirements Dictionary provide support for the above). Acronyms stand for: DFD: Data Flow Diagram/Design, CFD: Control Flow Design PSPEC: Procedural SPECifications CSPEC: Control SPECificationsExplanation / Answer
Structured Analysis (SA) in software engineering and its allied technique, Structured Design (SD), are methods for analyzing and converting business requirements into specifications and ultimately, computer programs, hardware configurations and related manual procedures. Structured analysis and design techniques are fundamental tools of systems analysis, and developed from classical systems analysis of the 1960s and 1970 Structured Analysis became popular in the 1980s and is still used by many. The analysis consists of interpreting the system concept (or real world) into data and control terminology, that is into data flow diagrams. The flow of data and control from bubble to data store to bubble can be very hard to track and the number of bubbles can get to be extremely large. One approach is to first define events from the outside world that require the system to react, then assign a bubble to that event, bubbles that need to interact are then connected until the system is defined. This can be rather overwhelming and so the bubbles are usually grouped into higher level bubbles. Data Dictionaries are needed to describe the data and command flows and a process specification is needed to capture the transaction/transformation information.[3] SA and SD were accompanied by notational methods including structure charts, data flow diagrams and data model diagrams, of which there were many variations, including those developed by Tom DeMarco, Ken Orr, Larry Constantine, Vaughn Frick, Ed Yourdon, Steven Ward, Peter Chen, and others. These techniques were combined in various published System Development Methodologies, including Structured Systems Analysis and Design Method, Profitable Information by Design (PRIDE), Nastec Structured Analysis & Design, SDM/70 and the Spectrum Structured system development methodology Structured Analysis views a system from the perspective of the data flowing through it. The function of the system is described by processes that transform the data flows. Structured analysis takes advantage of information hiding through successive decomposition (or top down) analysis. This allows attention to be focused on pertinent details and avoids confusion from looking at irrelevant details. As the level of detail increases, the breadth of information is reduced. The result of structured analysis is a set of related graphical diagrams, process descriptions, and data definitions. They describe the transformations that need to take place and the data required to meet a system's functional requirements.[8] The structured analyse approach develops perspectives on both process objects and data objects.[8] De Marco's approach[9] consists of the following objects (see figure)[8]: Context diagram dataflow diagram, process specifications, and a data dictionary, Hereby the Data flow diagrams (DFDs) are directed graphs. The arcs represent data, and the nodes (circles or bubbles) represent processes that transform the data. A process can be further decomposed to a more detailed DFD which shows the subprocesses and data flows within it. The subprocesses can in turn be decomposed further with another set of DFDs until their functions can be easily understood. Functional primitives are processes which do not need to be decomposed further. Functional primitives are described by a process specification (or mini-spec). The process specification can consist of pseudo-code, flowcharts, or structured English. The DFDs model the structure of the system as a network of interconnected processes composed of functional primitives. The data dictionary is a set of entries (definitions) of data flows, data elements, files. and data bases. The data dictionary enmes are partitioned in a topdown manner. They can be referenced in other data dictionary entries and in data flow diagrams.
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