The User Interface

Advances of Science and Technology have put to man in plane intermediate between tangible and intangible computacionalmente speaking, is now so common to coexist with computer daily that every time is made more imperative the best man-machine interaction through a suitable interface (User interface), that offers as much comfort him, as efficiency.

The present work is an introduction to the world of the User interface, in they are the basic concepts and slight knowledge that will allow ahead in entering to us in this scope more.

Those basic interfaces that include things or objects like menus, windows, keyboard, mouse, "beeps" and some other sounds that the computer does, in general, all those channels by which one allows to the communication between the man and the computer.

The fundamental idea in the interface concept is the one of mediation, between man and machine. The interface is what "average", which ensure communications, the interaction, between two systems of different nature, typically the human being and a machine like the computer. This implies, in addition, that it is a translation system, since both "different languages speak": verb-iconic in the case of the binary man and in the case of the electronic processor. Of one more a more technical way it is defined to User interface, like set of components used by the users to communicate with the computers.

The user directs to the operation of the machine by means of instructions, denominated generically entrances. The entrances are introduced by means of diverse devices, for example a keyboard, and becomes electronic signals that they can be processed by the computer. These signals are transmitted through circuits known like bus, and are coordinated and controlled by the unit of central process and a known software like operating system. Once the UPC has executed the instructions indicated by the user, it can communicate the results by means of electronic signals, or exits, that are transmitted by the bus to one or more output devices, for example a printer or a monitor.

Summarizing then we can say that, a software interface is the part of an application that the user sees and with which interacts. It is related to the underlying structure, the architecture, and the code that the work does of software, but it is not confused with them. The interface includes the screens, windows, controls, menus, metaphors, the aid in line, the documentation and the training. Any thing that the user sees and with which it interacts is part of the interface. An intelligent interface is easy to learn and use. It allows the users to make his work or to carry out a task in the way that does more feeling for them, instead of having to adjust to software. An intelligent interface is designed specifically for the people who will use it.

Of this general classification it is possible to be giving off some, thus for example according to his evolution we have them user interfaces run in parallel with the one of the operating systems; in fact, the interface at the moment constitutes one of the main elements of an operating system.

Next are the different interfaces that historically have been appearing, exemplifying them with the successive versions of the more popular operating systems.

He is the characteristic one of the TWO, the operating system of the first PC, and is the oldest style of man-machine interaction. The user writes orders using a formal language with a vocabulary and an own syntax (the mandates in the case of the TWO). A keyboard is used, typically, and the orders are directed to conduct a battle.

The user usually does not receive much information on the part of the system (example: indicator of the TWO), and must know how the computer works and where they are the programs (nothing is hidden to the user). The model of the interface is the one of the programmer, not the one of the user. Example of the DIR-DEL-DIR, by the lack of information of answer of the TWO. Other times, however, she is excessive: it labels of the volume in the DIR.

Disadvantage: load of memory of the user (must memorizar mandates; the aid is even difficult to read); not always suitable names to the functions, meaning of mandates badly included/understood sometimes (several mandates with the same one or seemed meant, like Of and the ERASE); inflexible in the names (Of and the noncDelete).

Advantages: powerful, flexible and controlled by the user, although this is an advantage for experienced users. The syntax is strict, and the errors can be graves

C:\TMP\>dir

The volume in C drive is PCDOS_6

Serial number of the Volume is 1D8F-82B0

Directory of C:\TMP

 .            < DIR >       02-02-98   21:08

.            < DIR >       02-02-98   21:08

ABCD          < DIR >       02-02-98   21:23

LETTER    DOC        1,107 22-10-96    9:51

        4 archivo(s)        1,107 bytes

                       24.862.720 free bytes

C:\TMP \ >

In sum, a CUI is adapted for expert users, does not stop noveles. For those are more expresses, reason why a CUI like part of an interface can be designed, so that it is possible to be used once experience is had.

A menu is a list of options that are in the screen or a window of the screen so that the users choose the option who wish (it see example). The menus allow two things: to sail within a system, being presented/displayed routes that take from a site to another one, and to select elements of a list, that represent properties or actions that the users wish to make on some object.

The interfaces of menus appear when the computer becomes a tool from user and not only from programmers. The present graphical or OO interfaces continue using this type of interfaces (the different styles from interfaces are not mutually exclusive).

Different types from menus exist. First they were the menus, structured jerárquicamente .

The bar menus, located in the superior part of the screen, profusely are used in the present applications. They contain a list of generic actions that take step to pull-down menus where they take shape.

These menus can take to others as well: they are the cascade menus. They can change dynamically, and deshabilitar options that are not available in a while dice (marking them habitually in gray).

The trowels or bars of tools are graphical menus with actions, tools and options that can be placed in the screen. They are used much in graphical programs.

The contextual menus or menus pop-up are most recent. They are called thus because the content of the menu depends on the work context of the user. They contain solely the options that are applicable to the selected object, plus some of use frequents that also they are accessible from the menu of barra.

The interfaces of menus, or structured, are good for sporadic users noveles or. They are easy to learn and to remember. Simple and advanced menus can exist, to adapt to the type of user.

Precautions: not to occupy too much space of the screen, to remember the accumulated information of preceding menus, not to place too many elements in the menu, to group them of logical way (not in alphabetical order, for example; this aid to remember them), to allow the personalización on the part of the user, to use a suitable and consistent terminology within the program and with other programs (Exit, Quit, Escape, Close, Return, Back). The interfaces of menus will be used normally in conjunction with the other styles of interfaces.

Developed originally by XEROX (system Xerox Star, 1981, without commercial success), although popularized by Apple (Steven Jobs was inspired by the works of Xerox and created the Smooth Apple, 1983, without success, and Apple Macintosh, 1984, successfully had to a great extent to its advertising campaign).

The three more common styles of graphical interfaces man-computer are: What you see she is what you can obtain (WYSIWYG What you see is what you get), direct Manipulation and Interfaces of user based on icons.

A GUI is a graphical representation in the screen of the computer of the programs, data and objects, as well as of the interaction with them. A GUI provides to the user the tools to conduct its operations, more than a list of the possible operations that the computer is able to do.

Characteristics of a GUI:

An important characteristic is that the GUI allows to manipulate the objects and information of the screen, to not only present/display it.

In order to use a GUI, the users they must know (or learn) a series of concepts: organization of the system (files, directories in Win95), different types from icons and effect of the actions on them, basic elements of a window, use of the controls of the GUI, use of the mouse.

The GUI uses the style object-action, in contrast to the action-object of the CUI or the interfaces of menu. The user selects an object, and later the action to make on this object. The objects are the main center of attention of the user, which is more natural and next to its mental model.

Its aspect is similar to the one of the GUIs. The difference is based in the underlying model: the GUIs are interfaces oriented to the application, whereas the OOUIs is oriented to the object. The table following sample the main differences between both styles of interface:

Interfaces oriented to the application	Interfaces OO
The application consists of an icon, a main window and several secondary ones	The product consists of a collection of seen objects that they cooperate and of these objects
The icons represent open applications or windows	The icons represent objects that can be manipulated directly
The users must open an application before working with objects	The users open objects like views in the writing-desk
He provides to the user the functions necessary to make the tasks	He provides to the user the materials necessary to make the tasks
He is centered in the main task determined by the application	He is centered in the entrances and exits of the objects and tasks
The related tasks are supported by other applications	The related tasks are supported by the use of other objects
Rigid structure: function	Flexible structure: object
The users can be catched in a task	The users do not have to be catched in a task
The users must follow the structure of the application	The users can make tasks to their own pleasure
Many applications are required: one by task	Few objects are required, that are reused in many tasks

The objective of the OOUI is that the user concentrates itself in his tasks instead of in the computer and how to use the applications and files necessary to fulfill its objectives. For that reason the organization of the system to the user hides (Example of the direct access in Windows95-OS/2).

The style of interaction of the OOUIs is the one of object-action (also it occurs in the GUIs, although mixed with the style action-object). The window is an object window, not an application window; they disappear because the bar menus and take terrain the contextual ones.

The objects can be classified in three categories: data, containers and devices. On them different views are defined (for example, the aid constitutes a Vista of the object). To define the objects and the views is most complicated of the design of the interface. The object must be familiar to the user (to fit with its mental model, supported in its daily life), and be related to the real world: use of the metaphors.

An example of which it is tried with an interface OOUI is to consider a document like an object on which to make tasks such as of incorporating graphs and texts, with no need to use programs different for each one from them. These programs usually have functions that are overlapped, with the consequent extra cost in space and money.

At the moment a mixture of products oriented to the application and the object exists, although a migration to these last ones is taking place. The applications are opening the way to sets of objects.

When designing user interfaces must have in account the cognitivas abilities and of perception of the people, and adapt the program to them.

Thus, one of things more important that an interface can do is to reduce the dependency of the people of its own memory, not forcing them to remember things unnecessarily (for example, information which it appeared in a previous screen) or to repeat operations already conducted (for example, to introduce a same data repeated times).

The person has abilities different from the machine, and this one must use hers to avoid those of that (as for example the little capacity of the memory of short reach).

PASSAGES FOR THE INTERFACE DESIGN

Classic Steps

In the process of design of an user interface four phases or steps can be distinguished fundamentales:

It is to say to make specific through requerimentación techniques, what type of users is going to use the program, what tasks are going to make the users and how they are going them to make, what demands the users of the program, in what surroundings the users develop (physical, social, cultural).

It is important to dedicate to time and resources to this phase, before entering the codification. In this phase the objectives of usabilidad of the program are defined, the tasks of the user, the objects and actions of the interface, the icons, views and visual representations of the objects, the menus of the objects and windows. All the visual elements can be made first by hand and soon refine with the suitable tools.

He is interesting to make a previous prototype, one first version of the program that is made quickly and allowed to visualize the product to be able to prove it before codifying it definitively.

To validate the user interface.

Tests of usabilidad of the product are due to make, if possible with the own end users of the same one.

It is important, in sum, to make a design that leaves from the user, and not of sistema.

11 passages in the process of centered design "in the tasks" exist, similar to the previous one but that it detachhes some implicit activities in others, thus:

Too many objects in the screen are not due to place, and those that exist must be distributed well. Each visual element influences in the user not only by itself, but also by its combination with the rest of present elements in the screen.

The number of visual elements that they perceive is: in case a) 1 (the bottom); in b) 3 (the line, which is above and what it is underneath); in c) they are 5 (the space outside the box, the box, the line and the space raises and underneath this one); finally, in d) the number rises to 35, following the same criterion. Conclusion: each new element that is added influences more than what it thinks about the user.

Analysis of Color: it is probably the element of the interface that with more frequency badly is used. The color communicates information, is not only decorative (example: to reinforce error messages).

Suitable combinations must be used (for example, the trowels provided by the operating systems). The color must attract the attention, but not tire after awhile of work.

It is specially important to follow the lines of design existing. Basic principle: to design first in black and white, and soon to add the color.

Audio Analysis. First it is precise to see when he is more appropriate than the visual reconnaissance. Second, to determine the suitable sound. Third, to allow the personalización (volume and decontamination). As in the case of the colors user's guides exist. In opened places of work, he can little be effective; in addition, he can be embarrassing for some people. The sound must be used to inform, not when it does not add anything new (for example, a message of warning of mail or welcome, respectively, when initiating a work session).

Analysis Animation. It is defined as a change in the time of the visual appearance of a graphical element. Examples of its use: progress of actions (copy of Windows 95 files, installation of programs), been of possible processes (printer icons), actions (changes in the cursor when moving the mouse). The animation can help to emphasize important icons, to show the state of a particular object or to explain its behavior.

International design. A use must be done adapted of the terminology. There is much work in this field. It must be had well-taken care of with the cultural differences (gestures, terminology, drawings, formats of telephones or calendars, etc.).

Analysis and Election of controls. Often the doubt of what controls exists utilizar.
In fact an only correct form does not exist. An aspect to consider is the scalability (menu of 10/1000 elements; example: programs of the menu beginning of Windows 95).

Example of alternatives: to use a trowel or bar menu, to allow to drag objects or not (problem: visual indication does not exist of which the object can be dragged: what objects can be dragged? to where they are possible to be dragged? what will happen when they arrive there? the action will be able to be undone).

Diverse guides of design exist removed from experts and committees, that they previously complement to the studied gold rules. To mention some of them:


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