Structured Analysis and Design


Structured system analysis and design method

A Structured Method helps software developers to cope with large and complex software. This method defines structured steps in software development process, starting from planning, analysis, design, implementation, and supporting. Analysis step defines and clarifies user and system requirements. During structured analysis, ERD and DFD are produced.


The ERD (Entity-Relationship Diagram) is presented to define and clarify entities, attributes, and their
relationships, and constraints applied to them. DFD (Data Flow Diagram)  depicts the system components—processes, external entities that interact with the system, and information flow in the system.

After you understand the problem clearly, it is the time to solve it. System design defines a solution to the problem. Structured design tasks are performed to translate what produced in system analysis to blueprint of the system that can be implemented. During structured design, the four design models are presented.
structured design models
-Data design transforms ERD in to data structures required to implement the software.
Entities, attributes, and relationships are the basic for design activities.
-Architectural design define a higher-level structure of the system. The higher-level structure of the system depicts the relationship between the structural components or modules of the system. Structure Chart is a good visual presentation of Architectural design.
structured design models

-Interface design  defines interaction of people with the system, and the system with other systems that work with it . It provides the best way for people and other systems to interact with the system. Data Flow Model can be a good input for interface design.
-Procedural design transforms the structural components or modules of the system architecture in to procedural description of the components. Pseudo-code or Flow Chart is a good tool to do the procedural design.

When program modules are designed, coding begins. Structured programming use standard control structures to improve clarity, and maintenance. Structured programming encourages top-down development. A top-level function is expanded down in to more detail components. Structured programming use SEQUENCE, IF ELSE, and LOOP to facilitate top-down development. Structured programming languages initially used are ALGOL, Pascal, PL/I, and Ada. C is the most popular structured programming language today.


 

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