System Development Model

 

In order to design a good system, traditionally, the developers have used the Waterfall model.

 

As waterfall flows from the top to the bottom, the system model shows the development process from the top to the bottom in steps.  As water does not rise from a lower level to a higher level, it is presumed that once a step in the model is over, it is not required to go back. This model fits well when the changes into the requirement specifications are not required frequently.  The minor changes can be taken care of through a maintenance process or through small design changes.  The waterfall model applies well to the basic rule based data and information processing systems in accounting materials, production and personnel.

 

However, some systems are more dynamic and require changes in specifications more often to continue to be useful.  These modifications are termed ad the versions of the basic model. One of the popular model developed by Boehm is a spiral model.

 

A spiral model fits well, when we are developing large systems, where the specifications cannot be ascertained in one stroke completely and correctly. Some of them get surfaced when the system is put to use after its testing. The continuous revision of these steps in the system development is very common and then the designers call them as versions. The new version provides an additional functionality, features, and facilities to the user, and addresses the issues of the users of the system viz.  performance, response, security and so on, irrespective of which development model is used in developing the system. The user  wants the system to be user friendly, reliable and effective, and  one which gives correct results, while the developer wants, the system easy to modify, easy to understand, portable and compatible to other systems.

 

The definition of a good system varies with the system's environment.  In some systems the performance is the key measure of a good system while in other cases the ability to change fast is a key measure of a good system while other cases the ability to change fast is a key measure of a good system.  In some cases the user friendliness could be a measure of good system.  In all the cases, however, the correctness of the result is a good system.  In all the cases, however, the correctness of the result is a common measure, making them reliable and dependable for the business operations.

 

The speed and response are the performance measures in case of large volume transaction based systems designed for real time applications. The flexible design is a measure of performance where the system needs continuous modifications to meet the revised requirements of the specifications. When it comes to a complex system the user friendliness and the ease of operations become the measures of a good system.  In other words, a good system design considers the environment and the users, and incorporates all the needs and expectations so that its utility is the highest.