user interface design in software engineering and their principles

user interface designing in software engineering
User Interface Design


User Interface

User interface refers to the method and devices that are used to accommodate interaction between the machines and the user (Shneiderman 1986; Bass 1991).User interface can take on many forms, but
always accomplishes two fundamental tasks:
  •   Communicating information from the machine to the user,and
  •   Communicating information from the user to the machine.
  The most common communication bridge between a person and a computer system is a visual display terminal (VDT).A well-designed screen can :                                                                           

  •  Increase human processing speed.
  •  Reduce human errors,and
  •  Speed computer processing time.
According to the Oxford English dictionary, an interface is :
  • A surface differentiating two parts of matter or space and forming their common limits. 
  • A place or region, or a piece of equipment, where interaction occurs between two systems, organizations or persons.
There are several other perceptions about User Interface.
  • "The UI is the cross-connection between the world of the users and the world of the product."
  • "The user interface is only the part of the system by which users interact with the systems for completing a task."
  • "It is only the sub-system by which the product reveals itself to the users and behaves in relation to the users' needs"
  • "As business perspective the user interface(UI) is only the product for the customers"  

Evolution Of User Interfaces  

The first computers had user interfaces(UI) that were as fundamental as the computers themselves. The computer's communicated information through the blinking of lights and the user's communicated information to the computer by using mechanical switches. Only the highly trained specialists were able to actually communicate directly with a computer.

The next stage of evolution had computers communicating to users through printing device, and the users communicating to the computer through punch card.This was an improvement, but still cumbersome and inefficient. It was rare that everyone but a computer specialist would actually communicate directly with a computer.

User interfaces left the dark ages when video screens were used to communicate information from the computer to the user, and typewriter-style keyboards were used to communicate information directly to the computer. This huge discovery helped to allow every user to communicate directly with a computer. But since the video screens were limited to displaying only the characters that were found on the keyboard, the usefulness of the user interface was constrained by the same limitation. Users were needed to learn commands that were normally tailored more to the computers than the users. Before getting started with the computer it was mandatory to training.

User interfaces entered the modern era when innovative designers broke away from the Character-based user interface (CUI) paradigm and invented the Graphic User Interface (GUI).

There were two major factors that separated GUI paradigm from CUI paradigm:

  • One was the widely use of graphics to communicate data(information) to the users visually not textually.
  • The other was to present a finite number of options to the users rather than requiring the users to memorize and manually enter commands from a virtually unlimited set of options.

In this way the interface was focused on the needs of the human beings,rather than the other way around.This significantly reduced the training that was necessary to use a computer,and for the first time
Uninitiated users were able to become productive almost immediately.

Access to system functions 

The user interface provides access to the functions or capabilities of the software system. The design of the user interfaces is a sub-task of the design phase.

Designing for a single user type is relatively simple. Designing for multiple or varying user types is much ore difficult.

By separating the user interface from the system functions, several advantages can be realized:

Components can be separated based on the size of the user interface - which often accounts for up to 70% of the total code.
Less effort for maintenance.
Re-usability.
Use of screen generator packages.

User-Interface Design Principles

User-interface design is governed by several design principles (Shneiderman 1986; Maguire 1985). All fundamental principles are compiled by Talin in 1998 for designing the user interfaces that include some following principles:

14 Principles Of User Interface that you should be know.

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