2.2.4 N a t u r e o f s c r I p t l a n g u a g e s. What is the script of a language? Let's use some positions formulated «fathers - founders» of the given direction.

Dichotomy Usterhaut is the principle of classification of languages offered by John Usterhaut, a writer of the «Тсl» language. According to his approach the high level of languages is divided into languages of system programming and into script. The last, ones are, called also as languages, or poorly typed, or in general without typical. They have no means for representation of complex data structures and are normally interpreted. The scripts, as a rule, cooperate with other program, frequently as a pasting, or with a menu function given by the interpreter.

Larry Wall, the writer of the language «Perl», professes some other approach. As he said, script languages should form «free from ethics artistic conditions». «The Script, - is underlined by him, is that you transmit to the actor, and the program is that is transmitted to auditorium».

If to continue the thought of Wall, it is possible to make a simple analogy between creation of the Internets - programs, theatrical performance and shooting of a movie.

The script - performance. The script at theatre is «interpreted» by the actors. As a result the auditorium sees the performance.

The script - movie. In the cinema the script is «compiled» in a taking material, which a film editor composes in film. As a result the spectator audience sees a movie.

The script - program. The script in Web-programming automatically, by interpreting/compilations turns to the program. As a rule the user sees the result of operation of the program.

The analogy is close to such branch, as the industry of entertainments, first of all it concerns the games, multimedia applications and authoring programs. Script languages are always rather actively used in computer games and applications of a multimedia, in particular, it concerns languages «SCUMM», «INF», «COG». The truth, generally they remain closed, being know-how. For strategic games, action-games and even of simulators the scripts are practically irreplaceable, as they allow shifting questions of programming of the scenes, strategies and scenes on shoulders of the designers. The application of script languages, though also specific implementation in the field of computer games, where reliability, memory size and rate of execution of a code are extremely important, is the best certificate of their potential efficiency [19].

As Robert Hubner, marks the conducting programmer of the company «LucasArts Entertainment», the in-house script language allows to establish the separate environment around your service computer. It protects a virtual machine fulfilling complex and often a varying game code, from «real» computers controlling game service computer. As the system of the scripts is much more floppy, rather than collection of the fixed effects, your service computer can fulfil more interesting functions, which originally were not planned.

The script language should be for means of fast bread boarding. The side between the script, considered as an intermediate product of the program) and completed product should be so imperceptible, that only a writer could understand, when the preliminary sample has turned to a finite product, depending on correspondence to the initial requirements.

The script language should be oriented to the rate and ease of mastering of base possibilities giving fast visible results. But it follows, that the language should be primitive. The path to the decision of the normal typical tasks even for starting should be short, simple and understandable. In this respect it should remind the native language: it happens enough to master some words and phrases, to understand you, to express thoughts in a proper way the native language is not possible even in a very old age.

Script language should to a lesser degree base on creation of a finite product with zero and in greater degree - on usage of those powers, which has the operating system, graphics environment, the applied service computer and other similar components, around of which is created the script. First of all it provides convenient operation at a level of textual lines, trying not to resort the intensive usage of complex types data.

So the script was added, in addition to habitual concepts of algorithm and program new. In this connection it is logical to divide languages into algorithmic, program and script. How can program and script languages coexist with each other in software engineering? By rating of «CI Labs Meta Group», from 70 up to 90 % of a multifunction of the new application provide at the expense of ready modules, whereas tunings and binding of the application need only 10-30 % of additional programming. The quite obvious lead-out arises, that the most critical modules and the service computers should fulfil program languages, whereas usage of their possibilities and embedding in the real environment is more reasonable for making the help of a script. For argument in protection of such position there can be the lead-out made by L. Prehelt in a course of probing, carried out by him: «Design and the drawing up of the programs in languages of «Реrl», «Python», «Rexx» and «Tel» occupies no more than halves of time necessary for programming on «C», «C ++» and «Java», and the length of the source text is twice less. It confirms again a rule Barry Boem, according to which the quantity of lines of the initial test established by the programmer in a unit of time, does not depend on the programming of the language [20].

The possible niche of script languages within the framework of creation of the program systems in relation to traditional program languages is pointed in operation. Shortly speaking, the essence is reduced to the following: any program is created in three forming - data, logic and front-end interface. If for convenience to take for a base the popular concept of «MVC» - «Model/View/Controller», the data, logic and interface will be displayed accordingly in the model, controller and sort. It is supposed, that the model appears normally in one copy, there must be many kinds, and the controller plays a role of a connecting layer between the first and the second. By the analogy to the concept of «MVC» all modules of the program system at such approach can be broken into three sorts [21]:

- Computer: a system layer, model;

- Converters: a connecting layer, controller;

- Script: an applied layer, sort.

A computer can be understood as any service computer and the identified component to it. The converters can be universal and specialized. The universal ones have common character specialized ones incorporate computers and script. They are more convenient for fulfilling all in languages of object-oriented programming. The division into three sorts is not necessarily should provide correspondence of computers, say, to level of model. The computer can be used at a level of the controller, if it is convenient for the given task.

The intercoupling between the program and script languages can be marked on Ershov’s model. According to it three complementary sorts of programming are selected [22]:

- Synthesizing, shaping of program fragments, components;

- Assembly, assembly of the program from ready fragments, components;

- Rendering concrete, adapting of the multiparameter program to the special conditions of its application.

Traditional languages in a significant degree dominate in synthesizing programming, whereas script - in rendering concrete. Their contact occurs in assembly programming, which becomes a boundary area of two different language worlds. Till now it is not clear, whether the programming is the induction or the deductive process. It is one more point of distinction of program and script languages.

The first ones profess faster induction approach, whereas the second - deductive.

As it is known, numerous attempts to establish the uniform universal programming language is completed unsuccessfully. But it concerned the language, instead of language environment and not of a linguistic system. Here it is important to mark, that A. P. Ershov was the author of an interesting idea - lexicon of programming, which he understood as a linguistic system with a phrase structure containing the formal notation for expression of all significant constructions, conditions, used at formulation, of the task, at synthesis and conversion of the programs». Script languages at their present stage of development, perhaps, are the closest to this idea.

As to the form of script languages, considerable influence on it has rendered and continues to render «C» language. The borrowing of informative ideas by script languages is carried on awide front:

- Languages of the functional programming «Lisp», «Scheme»;

- Languages of processing of strings (lines) «Snobol», «Icon»;

- Object-oriented languages «Smalltalk», «Java», «Eiffel», «C»;

- Command languages by the jobs (definitions), command languages «сsh», «Rexx»;

- Command languages environment «Tel», «VBA»;

- Languages of sectoring/macroprocessing «SGML», «TeX»;

- Languages of simulation analysis of discrete systems «GPSS», «SIMSCRIPT», «SLAM II».

What is the effect of program languages on design and development of languages script? Here it is possible to select three directions:

- Usage of object-oriented programming, practically any new script language supports object model;

- Usage of ideas of old languages «Lisp», «SNOBOL»;

- Languages of the functional programming and languages of processing of strings, lines on the dynamic nature are closest script;

- The appearance of the «Java» language, number of script languages which are most closely integrated with «Java».

Despite of huge efforts, which were undertaken by the leaders of the program industry led by «Sun Microsystems», the «Java» language in area the Internet - programming has failed to borrow of prevailing heights. Whereas in the field of intermediate software, creation of components and server decisions its role is rather appreciable. The niche which has been not occupied in the «Java» language has appeared, and it has established ground for appearance of such languages, as «Curl».

On what paths will there be a development of script languages, what ideas will be for catalysts of the process of their further perfecting? The answers to these questions contain in the defined sense in the words of famous J. Becus: «There are numerous certificates that the functional style of programming can surpass the style of fon Neyman. Therefore for the programmers it represents the large value of development of the new class of models of computer systems, which embody such style and do not suffer by an inefficiency, apparently, inherent to systems based on lambda - numeration. Only when such systems and their functional languages will prove the superiority over traditional languages, we shall receive an economic base for the development of new sort of the computer, which can realize them in the best way.

Having made the given analysis, it was clarified, that the best language for creation of the multimedia tutorial is «HTML» language with integrated «Java» scripts in it. The given system at usage will provide maximum speed, and also will give possibility not only for local training, but also the possibility of publication of the multimedia tutorial in a network of the Internet.