Structured design

In software engineering, structured analysis (SA) and structured design (SD) are methods for analyzing business requirements and developing specifications for converting practices into computer programs, hardware configurations, and related manual procedures.

Structured analysis and design techniques are fundamental tools of systems analysis. They developed from classical systems analysis of the 1960s and 1970s.

Structured analysis became popular in the 1980s and is still in use today. Structured analysis consists of interpreting the system concept (or real world situations) into data and control terminology represented by data flow diagrams. The flow of data and control from bubble to the data store to bubble can be difficult to track and the number of bubbles can increase.

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. Bubbles are usually grouped into higher level bubbles to decrease complexity. Data dictionaries are needed to describe the data and command flows, and a process specification is needed to capture the transaction/transformation information.

SA and SD are displayed with 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.

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