Chapter 8, Problem 1Q

Program Plan Intro

An overview of system design phase.

Explanation of Solution

A system design consists of user interface, inputs-outputs and an architecture design. A good system design provides reliability, effectiveness and maintainability.

• The main function of a good system design is to find errors, handle it and correct it wherever required. The error handling should be controlled so that it does not cause damage to the system.
• Once a system is deployed, there is no guarantee for no changes to be made in the system. Hence, the system design should support future changes in order to accommodate changes in user requirements or adapting to a new technology.
• An effective system meets the needs of the users and supports the business.

A few points to remember when designing a system are as follows:

1. The designer should think like a user and anticipate requirements. Also, the system designer should keep in mind the set of inputs and outputs, and any exceptions, if any. The designer should not burden the user with a variety of choices as it might confuse him/her and may cause system damage.
2. The system designer should model the system in such a way that it is easy to modify later on, when necessary. For example, if an attribute like ‘address’ maybe later broken down in parts like, ‘flat number, ‘street’, ‘locality', etc. The system should be able to work as efficiently with these attributes as it did, with the previous attribute.
3. The designer should allow the user to set constraints as per his/her requirements. For example, the user may want to query to check a list of employees who have more than $5,000 in their accounts. Here, the value of $5,000 should be set by the user. It may be possible for the user to query for the same using the constraint as $3,000. Hence, this decision must rest with the user.