of theme:
Compose: K. Zubritskaya
In activity of the modern enterprise the information becomes one of the major industrial resources, being allocated in the independent factor of successful business. The information component now is an irreplaceable part in work of any organization level with such components as the staff, clients, trade channels, technologies. The information cannot be consumed directly, therefore with growth of value of the information the role of means of its processing increases. If frequently cost of information base of corporation appears above production made by her and services if the information is always money, it is no wonder, that the market of control systems for today is estimated by databases in tens billions dollars.
In my final master's work various ways of the organization of access to data on a WEB-server will be investigated. The research problem consists in revealing the most effective and efficient, depending on those or other requirements to a specific target on the organization of access to data, systems of a sheaf " a platform - a http-server - DBMS ". The value judgment following from results of testing of work of these systems by everyone and their comparison on critical parameters are assumed. In addition development of the program module optimizing the given system to necessary requirements.
It is supposed, that there is a certain database to which it is necessary to provide access to the certain circle of users on a network. To make accessible any object which is being on a computer, connected to a network, it is necessary, that on a resource which plays a role of the Server, the centralized organized way of granting of access to services and resources was provided. Including access to storehouse of data - a database. In particular, to DBMS it is possible to give this access, using any from software called as a HTTP-server (WEB-server).
At research of existing http-servers it is necessary to make a start from on what platform it will be organized. We shall proceed from two platforms are systems of family Microsoft Windows and Unix/Linux-system. By an objective estimation of a great share of users, and generally managers and developers, reliability, flexibility, requirements to hardware maintenance, at last, cost of platforms of family Windows appreciably concede safety to Unix-like systems, it proves to be true time of continuous work without failures of the servers providing round-the-clock access to resources on a network. From OS Windows - systems which give opportunities for the organization of a WEB-server and a control system of databases - Windows NT/XP/2k. From Linux-systems are most popular, such as RedHat, ASPLinux, Fedora, Debian and some other. Separate item it is possible to tell, that and functional for server decisions platform FreeBSD is rather reliable.
During work revealing of the most effective and efficient, depending on those or other requirements to a specific target, systems of access to data is supposed. The system means itself the whole, consisting of universal popular a component that is key because the invention of "wheel" in the form of the complex software, nobody is necessary, it does not justify itself and cannot is universal. And the analysis of the connected work a component of the designer under the name " access to data " from the universal elements which have already proved during work of concrete system, can be useful. Elements are understood as various variations a web-server, субд and operational system under which these elements work.
Such value is supposed in opportunity to use means of testing of systems of access to data in the practical purposes.
Such project will have the certain value for beginners in this area, or what direct duties do not include support of the software. If there is a necessity of corporate access to any information, and the information is usually stored on-line, i.e. most likely it will be any database, it will be convenient to not waste time on independent testing during real work, that, certainly, does not protect from possible mistakes and damages if the system works not according to requirements shown to it. Using the theoretical review it is possible understand from what elements the system suitable for objects in view, and means of testing should to consist, will help to see ability of work of system evidently.
There is a number of technologies giving access to sources of data from appendices DBMS. Earlier when databases only started to use, to developers was the nobility only those databases with which they worked directly enough. But databases and their technologies developed quickly enough - from relational databases to not relational information storehouses, such, as e-mail and file systems. With the advent of client-server and multilevel architecture developers should understand all variety of technologies of databases.
In the majority of systems of designing of databases of the appendix are based on one type of databases. In such simple schemes the developer of the appendix can program directly, using the system interface of a database. Though the similar approach provides fast and effective access to data, there can be problems when the problem extends, and the developer should finish the program. At the given approach it means, that each ready program should have various versions with support of every possible types of databases. If the companies extend or are united one with another, the appendix should get access to the databases based on various platforms.
Technology ODBC provides the general interface for access to diverse databases of standard SQL. ODBC uses language SQL as the standard for access to data. Its interface is very convenient: one appendix can address to various databases SQL through the general set of commands. Thus, the developer can create and distribute appendices, not becoming attached to a concrete database.
It is possible to add also the driver of a database that the appendix could work with a database at the choice of the user. The manager of drivers is an intermediate link between the appendix and databases. Interface ODBC contains a set of functions which operates each tool of a database. If the appendix needs to replace used base, the developer simply replaces one driver with another, and the appendix can work as usually, without necessity of updating a code of the program.
Later some years ODBC become the standard for client-server access to databases. ODBC provides the standard interface which demands functions SQL and it is optimized under methods SQL. However that will occur, if it will be necessary to address to not relational database in which principles SQL (for example, Microsoft Exchange Server which storehouse does not contain data reletional) are not used.
My work does not mention mechanisms of work not relational databases since in a basis of their work a little bit other laws and mechanisms lay. Therefore all that is presented in work, concerns and can is used only concerning relational databases.
The cgi-script which personifies the mechanism of "dialogue" of the client with a server is at present developed. It, thus, is a basis for testing interaction of elements of system of access to data. The script is written on pelr, it will organize sql-inquiries to субд, using universal interface DBI, processes possible mistakes from a web-server and from DBMS and supervises speed of performance of inquiries to base.
Also the web-interface which is adhered to the above described script is created, it is some kind of its "human face", presented to the user for convenience.
Planned result of my final work will be revealing of the most effective and efficient, depending on those or other requirements to a specific target, systems of a sheaf "a platform (OS) - a HTTP-server - DBMS". The value judgment following from results of testing of work of these systems by everyone and their comparison on critical parameters are assumed.
Also it is supposed that result will be development of a universal remedy of testing for systems of access to data, not dependent from concrete DBMS, a web-server and platforms on which the given software is established.
Technologies of access to databases constantly develop. While one technology accustoms, already there is another. Only one remains constant: databases play more and more important role by development of appendices. The knowledge of the newest technologies and evolutionary changes which they cause, will help to find optimum technology for a current problem and to make the proved choice in case of necessary changes.