Structured Analysis and Design Technique (SADT) is a software engineering methodology for describing systems as a hierarchy of functions.
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Structured Analysis and Design Technique (SADT) is a diagrammatic notation designed specifically to help people describe and understand systems.[1] It offers building blocks to represent entities and activities, and a variety of arrows to relate boxes. These boxes and arrows have an associated informal semantics.[2] SADT can be used as a functional analysis tool of a given process, using successive levels of details. The SADT method allows to define user needs for IT developments, which is very used in the industrial Information Systems, but also to explain and to present an activity’s manufacturing processes, procedures.[3]
The SADT supplies a specific functional view of any enterprise by describing the functions and their relationships in a company. These functions fulfill the objectives of a company, such as sales, order planning, product design, part manufacturing, and human resource management. The SADT can depict simple functional relationships here and can reflect data and control flow relationships between different functions.
SADT has been developed and field-tested during the period of 1969 to 1973 by Douglas T. Ross and SofTech, Inc..[1][4] The methodology was used in the MIT Automatic Programming Tool (APT) project. It received extensive use starting in 1973 by the US Air Force Integrated Computer Aided Manufacturing program.
According to Levitt (2000) "it is part of a series of structured methods, that represent a collection of analysis, design, and programming techniques that were developed in response to the problems facing the software world from the 1960s to the 1980s. In this timeframe most commercial programming was done in COBOL and Fortran, then C and BASIC. There was little guidance on “good” design and programming techniques, and there were no standard techniques for documenting requirements and designs. Systems where getting larger and more complex, and the information system development became harder and harder to do so. As a way to help manage large and complex software. Since the end 1960 multiple Structured Methods emerged".[5]
In 1981 the IDEF0 formalism was published, based on SADT.[6]
The structured analysis and design technique uses a decomposition with the top-down approach. This decomposition is conducted only in the physical domain from an axiomatic design viewpoint. Because of this nonzigzagging process, there is no guarantee of functionality or productivity. Therefore, those methods faded away as the requirements for software systems increased and the object-oriented method was introduced.[7]
SADT uses two types of diagrams: activity models and data models. It uses arrows to build these diagrams. The SADT’s representation is the following:
The semantics of arrows for activities:[2]
The semantics of arrows for data:[2]