Structured Systems Analysis and Design Method (SSADM) is a widely used methodology for analyzing and designing information systems. It was developed in the United Kingdom in the late 1970s and early 1980s as a systematic approach to software development and system analysis. SSADM is characterized by its structured and hierarchical approach to modeling, with a focus on defining system requirements and processes. Here are key components and principles of SSADM:
Phases of Development:
- Feasibility Study: The initial phase involves determining whether the proposed system is feasible, considering factors such as cost, benefits, and technical viability.
- System Design and Specification: This phase focuses on defining the detailed requirements and specifications of the system, including data models, process models, and interface designs.
- Logical Design: In this phase, the logical structure of the system is developed, including data flow diagrams (DFDs) and entity-relationship diagrams (ERDs).
- Physical Design: The physical design phase involves specifying how the logical design will be implemented in terms of hardware, software, and databases.
- Build and Implementation: During this phase, the system is constructed based on the design specifications.
- Testing: Rigorous testing is performed to ensure that the system functions correctly and meets user requirements.
- Maintenance and Support: Once the system is operational, ongoing maintenance and support are provided to address issues and make enhancements as needed.
Structured Analysis:
- Data Modeling: SSADM uses data flow diagrams (DFDs) to model the flow of data through a system. DFDs represent processes, data stores, data flows, and external entities.
- Entity-Relationship Diagrams (ERDs): ERDs are used to model the relationships between data entities in the system.
- Data Dictionary: A data dictionary is maintained to define data elements, their attributes, and their relationships.
Structured Design:
- Functional Decomposition: SSADM employs a top-down approach to design, breaking down the system into smaller, manageable functions or modules.
- Data Structure Design: Designers specify data structures, including database tables and file structures.
- Interface Design: The design of user interfaces, forms, reports, and screen layouts is a critical part of SSADM.
Documentation: SSADM places a strong emphasis on documentation at every stage of the development process. Detailed documentation helps ensure clarity, traceability, and ease of maintenance.
User Involvement: SSADM encourages active involvement of end-users and stakeholders throughout the development process to gather requirements, validate designs, and ensure that the system meets user needs.
Quality Assurance: Quality control and assurance processes are integrated into SSADM to verify that the development process adheres to established standards and best practices.
Rigorous Testing: Extensive testing, including unit testing, integration testing, and system testing, is performed to validate the system’s functionality and reliability.
SSADM is often associated with the Waterfall Model, a sequential and linear software development approach. However, it is adaptable and can be used in iterative development environments as well. Over the years, SSADM has evolved and been integrated into broader methodologies and frameworks. While it may not be as commonly used as agile methodologies today, its structured approach and emphasis on requirements analysis and documentation remain valuable in certain contexts, especially in industries with stringent regulatory requirements.