This is an early, simplified version of a software application that has some of the functions of the eventual application but not the scale or performance. Specific types of prototypes are described below.
* Application Concept Prototype
An application concept prototype is a system developed to test and refine the underlying premise of an application.
* Application Package Prototype
This is a "canned" application tried out with a small group of users before its full-scale implementation.
* Calculations and Logic Prototype
These are examples of the computations for complex logic or calculations in an application.
* Data Entry Prototype
This is a shell routine or system to check the speed and accuracy of data entry, and to test validity and integrity checks.
* Data System Prototype
This is a small-scale database to test database contents and organization.
* Dialog Prototype
This is a simulation of the interplay of user actions and the intended system response.
* Partial-System Prototype
A partial-system prototype emulates a facet of an application.
* Pilot
A pilot is a system that is not yet fully operational. Whereas a prototype is used when the functions and detailed design of a system are not fully understood, in a pilot system the functions and design are thought to be understood, but the system is cut over in limited form so that experience can be gained with it before the full system is implemented.
If the final system is to have five hundred terminals, a pilot system might be initially operated with five. If the system is to be installed in one thousand dealerships, it might first be operated in ten. As a result of pilot operation, modifications are usually made before the system is fully deployed.
* Reporting System Prototype
This is a mock-up of reports provided to users.
* Screen Prototype
A screen prototype is a working model of the screens and their interaction that simulates the operation of the system once it is ultimately developed. The prototype lacks logic to process or display data. It can, however, demonstrate movements from one screen to another, simulating navigation through a real version of the system.
* System Prototype
A system prototype is an executable version of the system procedures. The prototype is based on the source code developed to implement the system, which is itself derived from the design specifications describing the procedure.
A prototype of the system will be produced to whatever level of detail is required. At a minimum, this will consist of an agreed-upon sequence of dialogs for the system, in whole or in part.
For each dialog in a prototype, the following will be produced:
* Menu screens
* Data entry screens
* Verification rules
* Procedures for invoking screens
Although the word "prototyping" suggests an analogy with engineering (where prototypes are used extensively), the prototyping of software is fundamentally different from the prototyping of machines.
In engineering, a machine prototype usually takes longer to build and is much more expensive than the ultimate product. Because the ultimate product may come from a mass-production line, the prototype would be needed for testing the product before the production line is built.
In software, there is no production line. Prototyping is practical only if the prototype can be built quickly and cheaply. Unlike production engineering, a software prototype is not a full-scale version of the eventual system; it is usually a simplified version that has some of the functions of the working system but not the scale or performance. It lacks features like security, auditability, recoverability, and the ability to handle large volumes, large databases, or many users.
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