Aero Engineering

Definition

A brief definition of Systems Analysis and Design is:

Work that involves applying analytical processes to the planning, design and implementation of new and improved information systems to meet the business requirements of customer organizations.

http://www.opm.gov/fedclass/text/GS-2200.htm

Systems analysis and Design (SAD) exists due to the fact that it allows business systems creators to adequately discover what tasks the new system has to perform, outline these tasks, and design and implement an adequately working system. With the use of SAD, all aspects of what a systems task has to be can be outlined before the design of the new system takes place. This is done to ensure that the system will perform what the end user wants of the system adequately and accurately.

Discipline

SAD is often perceived as a discipline, most likely because it is a near essential part of the creation of all new systems. SAD has been used for some time in the creation of new systems. It has been proven that through the use of SAD, systems are able to perform to the end-users requirements efficiently. Without the use of SAD, new systems would more than likely not execute the tasks required of it, or would do so very poorly. SAD aims to overcome any and all shortcomings in the development, implementation and usage of new systems.

Problems

SAD often involves the end user on a regular basis, and therefore ensures that the end user would be satisfied with the system upon its completion. Doing so benefits the system, the end user and the designer/implementer for it is near impossible for the system to not be able to perform something that the end user requires of it. These requirements are often discussed early on in the design stage, due to the fact that if it was done any later, changes to the requirements would more than likely be difficult to implement. Also, any hardware limitations can be discovered prior to a systems design. If new hardware is needed, this can be applied into the implementation phase of the project. Doing this ensures that there will not be any hardware incompatibility with the new system and that it would function smoothly.

Methodologies

Within Systems Analysis and Design are a multitude of different methodologies, each attempting in a slightly way to overcome any and all shortcomings in the analysis, design and often the implementation of new systems. Many different ways of which systems are designed are available.

Waterfall Model

One of the ways in which such methodologies are used is known as the waterfall method. The definition of the waterfall method is that any new system designed using such a method flows, much like a waterfall, from one step to another until the system achieves what it is designed to perform.

The waterfall model derives its name due to the cascading effect from one phase to the other. In this model each phase has a well defined starting and ending point, with identifiable deliveries to the next phase.

http://scitec.uwichill.edu.bb/cmp/online/cs22l/waterfall_model.htm

SSADM

One popular methodology that uses the waterfall model is known as the Structured Systems Analysis and Design Method (SSADM).

SSADM (in common with other structured methodologies) adopts a prescriptive approach to information systems development in that it specifies in advance the modules, stages and tasks which have to be carried out, the deliverables to be produced and furthermore the techniques used to produce the deliverables. SSADM adopts the Waterfall model of systems development, where each phase has to be completed and signed off before subsequent phases can begin.

http://www.comp.glam.ac.uk/pages/staff/tdhutchings/chapter4.html

The first step in waterfall model of SSADM is a feasibility study, whereby the system that is currently in place is analysed to see what the current situation is. This is often done through the use of data flow diagrams. If the current system is already adequate enough to cope with what the end user requires, then there is no need to create a new system.

The next step in the model is to analyze what the new system has to perform, and discover its requirements. This is done via questioning the end user to a high degree, and any other users that will use the new system. This is done to ensure that the system will be able to be used adequately to perform what each of the users requires.

The hardware is looked at in the next stage, so as to discover whether any upgrades will be needed. If hardware is needed, it is outlined in this section. If there is no evidence of any hardware being needed, it is also noted. However, more often than not, hardware will undoubtedly be needed due to the fact that some aspects of the current hardware will need upgrading to allow for the new system to operate adequately. It may be the case that a complete new set of hardware is not required, and thus, only specific upgrades are required. All of these factors are recorded and will be placed into the system before the actual system is implemented.

The next step in SSADM is known as logical system specification. During this step, the way in which the end user's interact with the new system is looked at, analysed and a new design developed. Enquiries, updates and the navigation around the system are looked at in order to ensure that the system is able to be used by all end user's.

The final step in the SSADM model specifies what language and features of the chosen environment are to be implemented. This stage prepares for the actual design of the new system physically, plans the approach of what to take while creating the new system while also completing and specifying the exact functions of the new system.

In total, SSADM is a much used method, because it seems to allow for all aspects of the design to be carried out efficiently and effectively. It does not however provide a means as to when the system will be implemented, nor does it say anything about how the system is to be tested and maintained. SSADM only allows for the design to take place.

Spiral Model

Another used methodology in SAD is the Spiral Model. The spiral model is not as much used compared to models such