Y.E.S: CHAPTER 13

SYSTEM DESIGN

Systems design is the process of defining the architecture, components, modules, interfaces, and data for a system to satisfy specified requirements.
Systems design is therefore the process of defining and developing systems to satisfy specified requirements of the user.
The logical design of a system pertains to an abstract representation of the data flows, inputs and outputs of the system.
The physical design relates to the actual input and output processes of the system.
This is laid down in terms of how data is input into a system, how it is verified/authenticated, how it is processed, and how it is displayed as output. To use an analogy, a personal computer's physical design involves input via a keyboard, processing within the CPU, and output via a monitor, printer, etc.

Alternative design methodologies

1. Rapid Application Development (RAD)

is a methodology in which a systems designer produces prototypes for an end-users.
The end-user reviews the prototype, and offers feedback on its suitability. This process is repeated until the end-user is satisfied with the final system.

2. Joint Application Design (JAD)

is a methodology which evolved from RAD, in which a systems designer consults with a group consisting of the following parties:

JAD involves a number of stages, in which the group collectively develops an agreed pattern for the design and implementation of the system.

Benefits of System Design

Improved system performance; individually tailored configuration advice demonstrates where improvement is necessary, and how to improve the system to regain lost performance.
Customers gain a detailed understanding of how their users use their system. This Usage Profile can be leveraged to develop future architecture changes.
Potential to learn of future concerns, allowing customers to take proactive measures to avoid problems.
A baseline performance level is established against which benefits can be compared and changes to the system predicted or foreseen.