2.0STRUCTURED SYSTEMS ANALYSIS AND DESIGN3
2.1DEFINITION OF SSADM3
2.2IMPLEMENTATION OF SSADM3
2.3APPLICATION OF SSADM5
2.4ADVANTAGES OF SSADM5
2.5DISADVANTAGES OF SSADM6
3.1DEFINITION OF WATERFALL MODEL7
3.2IMPLEMENTATION OF WATERFALL MODEL8
3.3ADVANTAGES OF WATERFALL MODEL9
3.4DISADVANTAGES OF WATERFALL MODEL10
4.1DEFINITION OF SPIRAL MODEL11
4.2IMPLEMENTATION OF SPIRAL MODEL14
4.3APPLICATION OF SPIRAL MODEL15
4.4ADVANTAGES OF SPIRAL MODEL15
4.5DISADVANTAGES OF SPIRAL MODEL15
5.1DEFINITION OF INFORMATION ENGINEERING16
Systems development strategies are formulas, frameworks or templates for building successful systems. They are formal documentation for the phases of systems development cycle. They define the precise objectives for each phase and the results required from a phase before the next one can begin. The may include specialized forms for preparing the documentation describing each phase.
Example of systems development strategies are:
• Structured Systems Analysis and Design Method.
• Information Engineering.
• Waterfall Model
• Spiral Model.
• Rapids Application development.
• Paris Model.
• V- Model.
The major requirements of these methodologies are:
1. User involvement;
2. Quality assurance of the system to be developed; and
3. Separation of logical and physical specification.
2. STRUCTURED SYSTEMS ANALYSIS AND DESIGN
2.1DEFINITION OF SSADM
Structured systems analysis and design method is the structured method developed by the United Kingdom Government’s Central Computing and Telecommunications Authority. It is the preferred method for very large government projects. The latest version 4+ allows the user to tailor the method to suit the size and the type of project under development. The main user of the method is, of cause, the United Kingdom government, and it is use is mandatory on many public sector projects. However, the fact that it is an established and open method and that SSADM skill are widely available, means that is becoming a defector standard method in the wider market place.
2.2IMPLEMENTATION OF SSADM
The most important techniques that are used in SSDM are:-
a) Logical Data Modeling:
This is the process of identifying, modeling and documenting the data requirements of the system being designed. The data are separated into entities and relationships.
b) Data Flow Modeling:
This is the process of identifying, modeling and documenting how data moves around an information system. Data flow modeling examines processes, data stores, external entities and data flows.
c) Entity Behavior Modeling:
This is the process of identifying, modeling and documenting the events that affect each entity and the sequence in which these events occur.
SSADM has six stages which are:-
• Stage 1 – Current System:
The first stage of SSADM is concerned with the analysis of current systems operations and current problems. At the end of this stage one should have a complete understanding of:- • Problems and requirements;
• Current data flows and processes;
• Current data; and
• Be able to satisfy users’ completeness and accuracy of our findings.
• Stage 2 – Specification of Requirements:
At this stage the “Current Physical” system definition is converted to a “Current Logical” system definition and to this is added logical solutions to the problems and requirements which have been identified to give the user several possible solution. Once the user has made his choice further detailed work may be carried out. The deliverable of this...