Artifact:  User-Interface Prototype

User-Interface Prototype	A user-interface prototype is a prototype of the user interface. For example, the prototype can manifest itself as: paper sketches or pictures bitmaps from a drawing tool an interactive executable prototype; for example, in Microsoft®Visual Basic®
Role:	User-Interface Designer
More information:	Guidelines:User Interface (General)
Purpose Properties Timing Responsibility Tailoring

Input to Activities: Review Requirements Detail the Software Requirements Identify Test Ideas Model the User-Interface Construct Architectural Proof-of-Concept Identify Testability Mechanisms Develop Training Materials Develop Support Materials

Output from Activities: Prototype the User-Interface

Purpose

The following roles use the user-interface prototype:

• requirements specifiers, to understand the user interface for a use case
• system analysts, to understand how the user interface impacts the analysis of the system
• designers, to understand how the user interface impacts and what it requires from the "inside" of the system
• those who test the classes, to plan testing activities

Properties

You can make three basic kinds of prototypes:

• Drawings (on paper)
• Bitmaps (drawing tool)
• Executables (interactive)

In most projects, you should use all three prototypes, in the order listed above.

Timing

The user-interface prototype is built early, during Inception or in the beginning of the Elaboration phase, and before the whole system (including its "real" user interface) is analyzed, designed, and implemented.

Note that the main purpose of creating a user-interface prototype is to be able to expose and test both the functionality and the usability of the system before the real design and development starts. This way, you can ensure that you are building the right system, before you spend too much time and resources on development.

In order to achieve this, early testing follows that the prototype must be significantly cheaper to develop than the real system, while having enough capabilities to be able to support a meaningful use test.

Responsibility

A user-interface designer is responsible for the integrity of the user-interface prototype, ensuring that the prototype contributes to a usable user interface according to the requirements from use-case storyboards and boundary objects.

Tailoring

Decide whether a prototype is suitable for your project.  Decide whether the prototype includes drawings, bitmaps, and/or an interactive executable.  Decide on how much of the user interface to prototype, and the depth and realism of any interactivity.  Decide whether the prototype is purely throwaway, or whether some aspects are intended to evolve into the end product.

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