System Design Phase

• The third phase in the software development life cycle is system design.
• System design is concerned with designing the processes that will solve a business problem.
• When designing an information system there are two dimensions that need to be considered
1. Logical design: design on paper
2. Physical design: design needed to implement components of the system
• The following issues need to be considered in your physical design
1. Hardware design: all computer equipment, including input, processing and output devices must be specified by performance characteristics.
2. Software design: all software must be specified by capabilities.
3. Database designL the type, structure and functions of the database must be specified.
• Logical and physical design can be accomplished using either the traditional structured approach or the object oriented system approach.
• Using the OO approach, we design key objects and classes of objects in the new or updated system.
• The final step in system design is to evaluate the various alternatives and select one that will offer the best solution for the organization goals.
• There are techniques used for evaluation
1. Feasibility Matirx
2. Candidate Matrix