Guidelines for writing text describing SADT diagrams.An activation and sequencing language used to transform a functional representation into a sequence of events.A scheme for explicitly assuring consistency between parent and child diagrams.Two-way arrows to show stimulus-response.Then that parent diagram is referenced on the decomposing child diagram.Īdditionally, there are constructs that add capabilities to the language, such as the following. The C-Number of the diagram that decomposes a box is placed underneath that box on the parent diagram. These C-numbers also link together diagrams in the model hierarchy. These codes are put in the lower right-hand corner of the SADT form. A C-number code is constructed from the author's initials and unique sequence number. During the development of an SADT model, a diagram with its boxes and arrows is usually redrawn several times, creating different versions of the diagram. Otherwise the same syntax is used for both diagrams.Ĭhronological numbers, called "C-Numbers" for convenience, are used to identify unique versions of a diagram. In a Data diagram the boxes correspond to data and the arrows correspond to activities. In an activity diagram the boxes correspond to activities and the arrows correspond to data. Each of these models consists of diagrams that are made up of 3 to 6 boxes and arrows. Each diagram is either a summary (parent) diagram or a detailing (child) diagram of the parent.Ī SADT model is made up of two types of diagrams, an activity diagram and a data diagram. Each SADT model consists of a set of related diagrams that are organized in a top-down manner. SADT should therefore be used in the planning, analysis and general design phases and other techniques should be used for detail design activities.Ī SADT model is graphical in order to achieve the benefits of the principles of structuring, especially top-down, levels of detail and hierarchy. It is generally not used for program design because the constructs necessary for sequence, selection and interaction are not represented within SADT. SADT did not evolve from a design technique, but was rather developed by examining the problems associated with defining systems requirements. It is useful methodology for system planning, requirements analysis and system design. Structured Analysis and Design Technique (SADT) was developed by Douglas T. Structured Analysis and Design Technique and Data Flow Diagrams
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