Structured analysis and design technique (SADT) is a

systems engineering Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their enterprise life cycle, life cycles. At its core, systems engineering util ...

and

software engineering methodology In software engineering, a software development process is a process of dividing software development work into smaller, parallel, or sequential steps or sub-processes to improve design, product management. It is also known as a software devel ...

for describing

system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment (systems), environment, is described by its boundaries, ...

s as a hierarchy of functions. SADT is a structured analysis modelling language, which uses two types of diagrams: activity models and

data model A data model is an abstract model that organizes elements of data and standardizes how they relate to one another and to the properties of real-world entities. For instance, a data model may specify that the data element representing a car be co ...

s. It was developed in the late 1960s by

Douglas T. Ross Douglas Taylor "Doug" Ross (21 December 1929 – 31 January 2007) was an American computer scientist pioneer, and chairman of SofTech, Inc. He is most famous for originating the term CAD for computer-aided design, and is considered to be the fath ...

, and was formalized and published as

IDEF0 IDEF0, a compound acronym ("Icam DEFinition for Function Modeling", where ICAM is an acronym for "Integrated Computer Aided Manufacturing"), is a function modeling methodology for describing manufacturing functions, which offers a functional model ...

in 1981.

Overview

Structured analysis and design technique (SADT) is a

diagram A diagram is a symbolic representation of information using visualization techniques. Diagrams have been used since prehistoric times on walls of caves, but became more prevalent during the Enlightenment. Sometimes, the technique uses a three- ...

matic notation designed specifically to help people describe and understand

s.D. Marca, C. McGowan, Structured Analysis and Design Technique, McGraw-Hill, 1987, 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 Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy Philosophy (f ...

John Mylopoulos John Mylopoulos (born 12 July 1943) is a Greek-Canadian computer scientist, Professor at the University of Toronto, Canada, and at the University of Trento, Italy. He is known for his work in the field of conceptual modeling, specifically the de ...

(2004)
Conceptual Modelling III. Structured Analysis and Design Technique (SADT)
Retrieved 21 September 2008. SADT can be used as a functional analysis tool of a given process, using successive levels of details. The SADT method not only allows one to define user needs for IT developments, which is often used in the industrial Information Systems, but also to explain and present an activity's manufacturing processes and procedures.
at Free-logistics.com. Retrieved 21 September 2008.

History

SADT was developed and field-tested during the period of 1969 to 1973 by

and

SofTech, Inc. SofTech, Inc. was a computer software company with offices in the United States and headquarters established in Lowell, Massachusetts. SofTech was a significant provider of software engineering tools and solutions in the 1970's as well as Product ...

D. T. Ross: Structured Analysis (SA): A Language for Communicating Ideas. IEEE Transactions on Software Engineering, SE-3(1), pp. 16-34
Abstract
/ref> 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 Integrated Computer-Aided Manufacturing (ICAM) is a US Air Force program that develops tools, techniques, and processes to support manufacturing integration. It influenced the computer-integrated manufacturing (CIM) and computer-aided manufacturi ...

program. According to Levitt (2000) SADT 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 COBOL (; an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural and, since 2002, object-oriented language. COBOL is primarily us ...

and Fortran, then C and

BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

. There was little guidance on "good" design and programming techniques, and there were no standard techniques for documenting requirements and designs. Systems were 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.Dave Levitt (2000
Introduction to Structured Analysis and Design
. Retrieved 21 September 2008. SADT was among a series of similar structured methods, which had emerged since the 1960 such as: *

Structured programming Structured programming is a programming paradigm aimed at improving the clarity, quality, and development time of a computer program by making extensive use of the structured control flow constructs of selection ( if/then/else) and repetition ( ...

in circa 1967 with Edsger W. Dijkstra. *

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 ...

around 1975 with

Larry Constantine Larry LeRoy Constantine (born 1943) is an American software engineer, professor in the Center for Exact Sciences and Engineering at the University of Madeira Portugal, and considered one of the pioneers of computing. He has contributed numerous ...

and

Ed Yourdon Edward Nash Yourdon (April 30, 1944 – January 20, 2016) was an American software engineer, computer consultant, author and lecturer, and software engineering methodology pioneer. He was one of the lead developers of the structured analysis tec ...

* Structured analysis in circa 1978 with

Tom DeMarco Tom DeMarco (born August 20, 1940) is an American software engineer, author, and consultant on software engineering topics. He was an early developer of structured analysis in the 1970s. Early life and education Tom DeMarco was born in Hazl ...

, Yourdon, Gane & Sarson, McMenamin & Palmer. *

Information technology engineering Data engineering refers to the building of systems to enable the collection and usage of data. This data is usually used to enable subsequent analysis and data science; which often involves machine learning. Making the data usable usually involves ...

in circa 1990 with James Martin. In 1981 the

formalism was published, based on SADT.

SADT topics

Top-down approach

The structured analysis and design technique uses a decomposition with the

top-down approach Top-down and bottom-up are both strategies of information processing and knowledge ordering, used in a variety of fields including software, humanistic and scientific theories (see systemics), and management and organization. In practice, they c ...

. This decomposition is conducted only in the physical domain from an axiomatic design viewpoint.

Diagrams

SADT uses two types of diagrams: activity models and

s. It uses arrows to build these diagrams. The SADT's representation is the following: * A main box where the name of the process or the action is specified * On the left-hand side of this box, incoming arrows: inputs of the action. * On the upper part, the incoming arrows: data necessary for the action. * On the bottom of the box, incoming arrows: means used for the action. * On the right-hand side of the box, outgoing arrows: outputs of the action. The semantics of arrows for activities: * Inputs enter from the left and represent data or consumables that are needed by the activity. * Outputs exit to the right and represent data or products that are produced by the activity. * Controls enter from the top and represent commands or conditions which influence the execution of an activity but are not consumed. * Mechanisms identify the means, components or tools used to accomplish the activity. Represents allocation of activities. The semantics of arrows for data: * Inputs are activities that produce the data. * Outputs consume the data. * Controls influence the internal state of the data.

Roles

According to Mylopoulos (2004) in the software development process multiple roles can or should be distinguished: * Author or developer of the SADT models * Commenters, who review the author's work * Readers or users of the SADT models * Experts, who can advise the authors * Technical committee or reviewers of the SADT models in detail * Project librarian, who govern the project documentation * Project manager, who governs the system analysis and design. * Monitor or chief analyst to assists SADT developers and users * Instructor to train SADT developers and users

Usage

SADT is used as diagrammatic notation in conceptual design of software engineering and systems engineering to sketch applications, for more detailed structured analysis, for requirements definition,Ross, Douglas T., and Kenneth E. Schoman Jr. "Structured analysis for requirements definition." Software Engineering, IEEE Transactions on 1 (1977): 6-15. and structured design.

References

External links

The IDEF0 methodA course about SADT diagrams
{{Authority control Systems analysis