Prototyping

what is Prototyping 

Prototype: Prototypes are experimental and incomplete designs which are cheaply and fast developed.  Prototyping, which is the process of developing prototypes, is an integral part of iterative/repetitive user-centered design because it enables designers to try out their ideas with users and to gather response. The main purpose of prototyping is to involve the users in testing design ideas and get their response in the early stage of development, thus to reduce the time and cost. It provides an efficient and effective way to refine and enhance interfaces through discussion, exploration, testing and iterative revision.

Types of prototyping: 

Software prototyping has many variations. However, all the methods are in some way based on two major types of prototyping: Throwaway Prototyping and Evolutionary Prototyping.

1). Throwaway prototyping: Also called close-ended prototyping. Throwaway or Rapid Prototyping refers to the creation of a model that will eventually be discarded rather than becoming part of the final delivered software. After preliminary requirements gathering is accomplished, a simple working model of the system is constructed to visually show the users what their requirements may look like when they are implemented into a finished system.

Rapid Prototyping involved creating a working model of various parts of the system at a very early stage, after a relatively short investigation. The method used in building it is usually quite informal, the most important factor being the speed with which the model is provided. The model then becomes the starting point from which users can re-examine their expectations and clarify their requirements. When this has been achieved, the prototype model is 'thrown away', and the system is formally developed based on the identified requirements. 

Summary: In this approach the prototype is constructed with the idea that it will be discarded and the final system will be built from scratch. The steps in this approach are:

• Write preliminary requirements
• Design the prototype
• User experiences/uses the prototype, specifies new requirements
• Repeat if necessary
• Write the final requirements

2). Evolutionary prototyping:

Evolutionary Prototyping (also known as breadboard prototyping) is quite different from Throwaway Prototyping. The main goal when using Evolutionary Prototyping is to build a very robust prototype in a structured manner and constantly refine it. The reason for this is that the Evolutionary prototype, when built, forms the heart of the new system, and the improvements and further requirements will be built.When developing a system using Evolutionary Prototyping, the system is continually refined and rebuilt.

Evolutionary Prototypes have an advantage over Throwaway Prototypes in that they are functional systems. Although they may not have all the features the users have planned, they may be used on an temporary basis until the final system is delivered.

In Evolutionary Prototyping, developers can focus themselves to develop parts of the system that they understand instead of working on developing a whole system.

To minimize risk, the developer does not implement poorly understood features. The partial system is sent to customer sites. As users work with the system, they detect opportunities for new features and give requests for these features to developers. 

Incremental prototyping: The final product is built as separate prototypes. At the end the separate prototypes are merged in an overall design. By the help of incremental prototyping we can reduce the time gap between user and software developer.

Extreme prototyping: Extreme Prototyping as a development process is used especially for developing web applications. Basically, it breaks down web development into three phases, each one based on the preceding one. The first phase is a static prototype that consists mainly of HTML pages. In the second phase, the screens are programmed and fully functional using a simulated services layer. In the third phase, the services are implemented.

Advantages of prototyping