SAD METHODOLOGIES

Objectives:• To know what are some SAD methodologies

that we can use.

• To know what is Business Process Reengineering vs. Reverse Engineering

• To know about Object-Oriented SAD

Different SAD Methodologies:

• Prototyping

• RAD (Rapid Application Development)

• XP (Extreme Programming)

PROTOTYPING

What is Prototyping?

• A worthwhile technique for quickly gathering specific information about users’ information requirements.

• Requires knowledge of the entire Systems Development Life Cycle before it is successfully accomplished.

What is its purpose?

• It is an information gathering technique that SA’s use to seek:• Initial reactions from users and management to the

prototype,• User suggestions about changing or cleaning up the

prototyped system,• Possible innovations for it, and• Revision plans detailing which parts of the system

need to be done first or which branches of an organization to prototype next.

Information gathered in the prototyping phase allows the analyst to set priorities and redirect plans inexpensively, with a minimum of disruption.

Prototyping an alternative to SDLC:

• Some analysts argue that prototyping should be considered as an alternative to the SDLC due to the following complaints about SDLC:• The extended time required to go through the

development life cycle. As the investment of analyst time increases, the cost of the delivered system rises proportionately.

• User requirements change over time. There is long interval between the time user requirements are analyzed and delivered and user requirements are evolving.

Prototyping an alternative to SDLC:

• Advantages of using Prototyping vs. SDLC:• The analyst effectively shortens the time between

ascertainment of information requirements and delivery of a workable system.

• Might also overcome some of the problems of accurately identifying user information requirements.

• Disadvantages of using Prototyping vs. SDLC:• Might prematurely shape a system before the problem or

opportunity being addressed is thoroughly understood.• Might result in producing a system that is accepted by

specific groups of users but that is inadequate for overall system needs.

But...

You are encourage to user prototyping as a part of the traditional SDLC: considering prototyping as an additional, specialized method for ascertaining users’ information requirements.

Kinds of Prototype

• Patched-Up Prototype• Constructing a systems

that works but is patched up or patched together.

• Example, an information system that has all the necessary features but is inefficient.

Kinds of Prototype• Nonoperational Prototype

• A prototype that is of a non-working scale but was set up to test certain aspects of the design.

• A non-working model of an information system may be produced when the coding required by the applications is too extensive to prototype but a useful idea of the system can be gained through prototyping the input and output only.

• Example, a full-scale model of an automobile that is used in wind tunnel test. The size and shape of the auto are precise but the car is not operational.

Kinds of Prototype

• First-of-a-Series Prototype• Involves creating a first full-

scale model of a system, often called a pilot.

• Example, the first airplane of a series. This prototype is completely operational and is a realization of what the designer hopes will be a series of airplanes with identical features.

Kinds of Prototype

• Selected Features Prototype• This type of prototyping builds

an operational model that includes some, but not all, of the features that the final system will have.

• Example, opening a new retail shopping mall that opens before the construction of all shops is complete.

Developing A Prototype:

1. Work in manageable modules• Manageable module is one that allows users to interact

with its key features but can be built separately from other system modules.

• Leave out features that are deemed less important.• The advantage is one does not need to build an entire

working system for prototype purposes.

2. Build the Prototype rapidly• Having the an operational prototype rapidly and early in the

SDLC allows the analyst to gain valuable insight into how the remainder of the project should go.

• This guards against over-committing resources to a project that may eventually become unworkable.

Developing A Prototype:

3. Modify the prototype in successive iterations• Its construction must support modifications.• Remember that a prototype will undergo several

modifications.

4. Stress the user interface• Make sure that your UI is developed enough to

enable users to pick up the system quickly and not be put off.

Advantages of Prototyping:

1. The potential for changing the system early in its development;

2. The opportunity to stop development on a system that is not working;

3. The possibility of developing a system that more closely addresses users’ needs and expectations.

Disadvantages of Prototyping:

1. It can be difficult to manage as a project in the larger systems effort.

2. Users and analysts may adopt a prototype as a completed system when it is in fact inadequate and was never intended to serve as a finished system.