19.1. Open systems

The real spread of the client-server architecture became possible due to the development and widespread introduction of the open systems concept into practice. Therefore, we will begin with a brief introduction to open systems.

The basic meaning of the open systems approach is to simplify the integration of computing systems through international and national standardization of hardware and software interfaces. The main reason for the development of the concept of open systems was the ubiquitous transition to the use of local computer networks and the problems of integrating hardware and software that caused this transition. Due to the rapid development of global communications technologies, open systems are becoming even more significant and large-scale.

The key phrase of open systems directed towards users is vendor-specific independence. Focusing on the products of companies that adhere to the standards of open systems, the consumer, who buys any product of such a company, does not get into her slavery. He can continue to increase the capacity of his system by purchasing products from any other company that complies with the standards. And this applies to both hardware and software and is not an unreasonable declaration. The real possibility of vendor independence is verified in domestic conditions.

The practical backbone of the system and application software of open systems is the standardized operating system. Currently, such a system is UNIX. As a result of long-term work, the companies supplying various versions of UNIX OS were able to agree on the basic standards of this operating system. Now all common versions of UNIX are generally compatible in terms of the interfaces provided to application (and in most cases system) programmers. As it seems, despite the emergence of the standard Windows NT system, it is UNIX that will remain the basis of open systems in the coming years.

Technologies and standards of open systems provide real and proven practice for the production of system and application software with portability and interoperability properties. The property of mobility means the comparative simplicity of transferring a software system in a wide range of hardware and software tools that meet the standards. Interoperability means simplifying the integration of new software systems based on the use of off-the-shelf components with standard interfaces.

Using the open systems approach is beneficial to both manufacturers and users. First of all, open systems provide a natural solution to the problem of generations of hardware and software. Manufacturers of such tools are not forced to solve all problems anew; they can at least temporarily continue to integrate systems using existing components.

Note that this creates a new level of competition. All manufacturers are required to provide some standard environment, but are forced to achieve it as best as possible implementation. Of course, after some time the existing standards will begin to play the role of deterring progress, and then they will have to be revised.

The advantage for users is that they can gradually replace system components with more advanced ones, without losing system performance. In particular, this is the solution to the problem of the gradual increase in computing, information and other computer system capacities.