Design information systems is called a multi-stage process of their creation and / or modernization by applying an ordered set of methodologies and tools. Design (as opposed to modeling) involves working with a still non-existent object and is aimed at creating an information system in the field of:

• processing objects of the future database,
• writing programs (including reporting and screen forms) that ensure the execution of queries to data,
• accounting for the functioning of a specific environment (technology).

If we single out the stage of designing information systems as a separate stage, then it can be placed between the stages of analysis and development. However, in practice, a clear division into stages is usually difficult or impossible, since design, formally starting with the definition of the project goal, often continues at the testing and implementation stages.

Information System Design Objective and Related Concepts

Today's leaders of public and private organizations are aware that the speed of information processing, which is constantly changing and growing in volume, is a matter of the company's survival in the market and a competitive advantage. In general, the target settings of projects for the creation of information systems are reduced to providing conditions that allow this information to be received, processed and used by creating a functional fail-safe system with sufficient:

• the level of adaptability to changing conditions,
• throughput,
• system response time to a request,
• level of security,
• the degree of ease of use.

An information system (IS) is a collection of information contained in a database and technologies (as well as technical tools) that provide information processing. In this case, technologies include the methods of detecting, collecting, processing, storing, distributing information, and the methods that allow these methods to be implemented. Information management in this case comes down to the application of these methods to control the planning, design, operation and analysis of IS. The design technology is based on the methodology chosen for a specific task as a set of principles, expressed in a single definite concept.

Organization of IC design

The organization of IC design is usually divided into 2 types:

1. Canonical design reflects the peculiarities of the technology of the original (individual) process.
2. Typical design, which is characterized by a typical design solution (TPD), is replicated and suitable for repeated use.

Canonical design is distinguished by the reflection of manual design technology, implementation at the level of performers, and the use of universal computer support tools.

Canonical design is used, mainly for local and relatively small ICs with minimal use of typical solutions. Adaptation of design solutions occurs only through reprogramming of software modules.

Canonical design is organized using a waterfall life cycle model. This involves dividing the process into the following stages and steps:

1. Pre-design stage. A technical assignment is being produced and drawn up. That is, the requirements for the IP are formed, its concept is developed, a feasibility study is drawn up and the TK is written.
2. The design stage provides for the preparation of draft and technical projects, the development of working documentation.
3. The post-project stage gives a start to measures for the implementation of IS, training of personnel, and analysis of test results. A part of this stage is the maintenance of IS and the elimination of the identified deficiencies.

Stages, if necessary, can be enlarged or detailed - combine successive stages, exclude "unnecessary" ones, start the next stage before the previous one is completed.

The typical design method is distinguished by the possibility of decomposition of the designed IS with division into components, which include software modules, subsystems, task complexes, etc. At the same time, typical design presupposes the mandatory availability of documentation describing in detail the technical design and adjustment procedures.

Decomposition can have several levels, which makes it possible to distinguish classes of TPDs:

• elemental - for a separate task (element),
• subsystem - for individual subsystems,
• object - industry standard design solutions containing the entire set of subsystems.

The possibility of implementing a modular approach is considered an advantage of elemental TPRs. However, in the case of incompatibility of different elements, the process of combining them leads to an increase in costs. Subsystem TPR, in addition to implementing a modular approach, make it possible to carry out parametric tuning for objects of different control levels. Problems with merging arise in the case of attracting a product of several different manufacturers ON. In addition, the adaptability of TPR from the standpoint of continuous process reengineering is considered insufficient. Object TPD, in comparison with the previous classes, differ big amount advantages:

• scalability, which makes it possible to use IC configurations for a different number of workplaces,
• methodological unity of components,
• compatibility of IC components,
• open architecture - the ability to deploy design solutions on platforms of various types,
• configurability - the ability to use the desired subset of IC components.

During the implementation of typical design, parametric-oriented and model-oriented approaches are used.

Basic IC design methodologies

The specific features of the design process make it possible to distinguish methodologies based on different principles. Among the main modern IC design methodologies, the following are called:

• SADT... Methodology functional modeling works based on structural analysis and graphical representation organizations as a system of functions. Functional, informational and dynamic models... The methodology is now known as IDEF0 notation (standard). The analyzed process is graphically represented in the form of a quadrangle, where regulatory and control actions are depicted on top, control objects are shown below, input data are on the left, and outputs are on the right.
• RAD... Rapid Application Development Methodology. In RAD, rapid application development is possible through the use of component-based design. The methodology is applied on projects with a limited budget, unclear requirements for IP, with a tight deadline. It is used if the user interface can be demonstrated in a prototype, and the project can be divided into functional elements.
• RUP... The RUP methodology implements iterative and incremental approaches. The system is built on the basis of the architecture of the information system, and planning and project management are based on the functional requirements for IS. The development of a general information system occurs in iterations, as a complex of separate small projects with their own plans and tasks. The iterative cycle is characterized by a periodic Feedback and adaptation to the IS core.

There are several classifications of methodologies: for the use of TPM, for the use of automation tools, etc. For example, according to the degree of adaptability, reconstructions are distinguished (when modules are reprogrammed), parameterization (when a change in parameters entails the generation of a design solution), restructuring (when a change in the model of a problem area accompanied by automatic generation of the design solution).

1.2.1 Concept and properties of the system

1.2.2 Concept and types of information systems

1.2.3. The structure and composition of the information system

1.2.4. Data processing system components

1.2.5. Organizational components of the information system

1.2.6. Information systems development trends

Literature: 4, p. 12-25; 5, p. 16–32; 7, c. 9–32.

1.2.1 Concept and properties of the system. System any object is called, which, on the one hand, is considered as a single whole, and on the other, as a set of interconnected or interacting components.

the term "system" is used mainly in two senses:

A system, as a certain property, consisting in a rational combination in the ordering of all elements of a certain volume in time and space, so that each of them contributes to the success of the entire object. This interpretation is associated with the understanding of the coordination and synchronization of the actions of the management personnel, united in order to achieve the set goals;

A system as an object with a rather complex, in a certain way ordered internal structure (for example, a production process).

The concept of a system covers a complex of interrelated elements that act as a whole. The system includes the following Components :

System structure- many elements of the system and the relationships between them. Example: organizational and production structure of an enterprise. The mathematical model of the structure is a graph.

Functions of each element of the system... Example: management functions - decision-making by a certain structural unit of the enterprise.

Input and output of each element of the system as a whole... Example: tangible or information flows entering or exiting the system. Each input stream is characterized by a set of parameters (x (i)); the values ​​of these parameters for all input streams form a vector function X. In the simplest case, X depends only on time t, and in practically important cases, the value of X at time t + 1 depends on X (t) and t. The system Y output function is defined similarly.

System behavior law - function linking system input and output changes Y = F (X).

Objectives and limitations of the system and its individual elements... Example: achieving maximum profit, financial constraints.

The quality of the system functioning is described by a number of variables u1, u2, ..., uN. Some of these variables (usually just one variable) must be supported in an extreme value, for example, max ul. The function ul = f (X, Y, t, ...) is called target function, or purpose. Often f does not have an analytical and generally explicit expression. The rest of the variables can be imposed (in general case bilateral) restrictions

aK<= gK(uK) <= bК, где2 <= К <=N.

Among the famous system properties it is advisable to consider the following: relativity, divisibility and integrity.

The property of relativity establishes that the composition of elements, relationships, inputs, outputs, goals and restrictions depends on the goals of the researcher.

Divisibility means that the system can be represented as consisting of relatively independent parts - subsystems, each of which can be considered as a system.

Integrity property indicates the consistency of the goal of the entire system with the goals of the functioning of its subsystems and elements.

The system, as a rule, has more properties than its constituent elements (Aristotle).

1.2.2 Concept and types of information systems. In connection with the application of new information technology based on the use of communication facilities, computers, the concept “ Information system "(IS).

Information system is a communication system for the collection, transmission, processing of information about the facility, providing employees of various ranks with information for the implementation of management functions.

An information system is created for a specific object. An effective information system takes into account the differences between levels of government, scope, and external circumstances, and gives each level of government only the information it needs to effectively implement its management functions.

The introduction of information systems is carried out in order to increase the efficiency of the company's production and economic activities through not only processing and storing routine information, automating office work, but also through fundamentally new management methods based on modeling the actions of the company's specialists when making decisions (artificial intelligence methods, expert systems, etc.), the use of modern telecommunications (e-mail, teleconferences), global and local computer networks, etc.

Depending on the degree (level) of automation, manual, automated and automatic information systems are distinguished.

Handheld ICs characterized by the fact that all information processing operations are performed by a person.

Automated ICs- some of the functions (subsystems) of control or data processing are carried out automatically, and some - by a person.

Automatic ICs- all functions of control and data processing are carried out by technical means without human intervention (for example, automatic control of technological processes).

According to the scope of application, the following classes of information systems can be distinguished:

Scientific research;

Computer-aided design;

Organizational management;

Technological process control.

Scientific IP are designed to automate the activities of scientists, analyze statistical information, and control experiments.

Computer aided design IC designed to automate the work of design engineers and developers of new equipment (technology). Such IPs help to carry out:

Development of new products and technologies for their production;

Various engineering calculations (determination of technical parameters of products, consumption rates - labor, material, etc.);

Creation of graphic documentation (drawings, diagrams, layouts);

Modeling of designed objects;

Creation of control programs for machine tools with numerical control.

Organizational Management IS are designed to automate the functions of administrative (managerial) personnel. This class includes management information systems for both industrial (enterprises) and non-industrial facilities (banks, stock exchanges, insurance companies, hotels, etc.) and individual offices (office systems).

Process control IC is intended for the automation of various technological processes (flexible production processes, metallurgy, energy, etc.).

1.2.3 The structure and composition of the information system. Almost all considered types of information systems, regardless of their scope, include the same set of components (Figure 1.2):

Functional components;

Data processing system components;

Organizational components.

Moreover, under control function means a special permanent duty of one or more persons, the fulfillment of which leads to the achievement of a certain business result.

Under functional components the system of management functions is understood - a full set (complex) of interconnected in time and space of management works necessary to achieve the goals set for the enterprise.

The whole process of managing a company is reduced either to linear (for example, administrative) management of an enterprise or its structural unit, or to functional management (for example, logistics, accounting, etc.) Therefore, the decomposition of the information system according to a functional attribute (Fig. 1.2) includes the allocation of its individual parts, called functional subsystems (SS) (functional modules, business applications) that implement the system of management functions. The functional feature determines the purpose of the subsystem, that is, what area of ​​activity it is intended for and what main goals, tasks and functions it performs. Functional subsystems largely depend on the subject area (scope) of information systems.

Figure 1.3 shows the functional decomposition of the information system of an industrial enterprise. Depending on the complexity of the object, the number of functional subsystems ranges from 10 to 50 items. As follows from the above figures, despite the different areas of application of IS, a number of functional subsystems have the same name (for example, accounting and reporting), but their internal content for different objects differs significantly from each other. The specific features of each functional subsystem are contained in the so-called "functional tasks" of the subsystem (Figure 1.2). Typically, management personnel either associates this concept with the achievement of certain goals of the management function, or defines it as work that must be performed in a certain way in a certain period. However, with the advent of new information technologies, the concept of “ task »Is considered more broadly: as a complete complex of information processing, providing either the issuance of direct control actions on the course of the production process, or the issuance of the necessary information for decision-making by management personnel... Thus, the task should be considered as an element of the control system, and not as an element of the data processing system. The choice of the composition of functional tasks of functional control subsystems is usually carried out taking into account the main phases of management: planning; accounting, control and analysis; regulation (execution).

Planning- This is a management function that ensures the formation of plans, in accordance with which the operation of the control object will be organized. Usually, long-term (5-10 years), annual (1 year) and operational (day, week, decade, month) planning are distinguished.

Figure 1.3 - Enlarged functional decomposition

information system of an industrial enterprise

Accounting, control and analysis- these are functions that provide data on the state of the controlled system for a certain period of time; determination of the fact and reasons for deviations of the actual state of the control object from the planned state, as well as finding the values ​​of this deviation. Accounting is carried out according to the plan indicators in the selected range (horizon) of planning (operational, medium-term, etc.).

Regulation (execution) Is a function that provides a comparison of the planned and actual indicators of the functioning of the control object and the implementation of the necessary control actions in the presence of deviations from the planned in a given range (segment).

In accordance with the selected functional subsystems (Fig. 1.3) and taking into account the control phases, the composition of the tasks of functional subsystems is determined. For example, a bank personnel management information system may contain the following functional subsystems:

Planning the number of bank personnel;

Calculation of the personnel payroll;

Planning and organization of personnel training;

Personnel movement management;

Statistical accounting and reporting;

Help on request.

The choice and substantiation of the composition of functional tasks is one of the important elements in the creation of information systems. It should be noted that it is the task (functional subsystem) that is the object of development, implementation and operation by the end user.

Analysis of functional tasks shows that their practical implementation in the context of information systems is multivariate. One and the same task can be solved (implemented) by various mathematical methods, models and algorithms (Figure 1.2). Sometimes this functional subsystem is called subsystem of software.

Among the many options for implementation, as a rule, there is the best one, determined by the capabilities of the computing system and the data processing system as a whole.

In modern information systems design automation systems, this component is part of the so-called banks of models and algorithms, from which the most effective ones for a specific control object are selected in the process of developing information systems.

1.2.4 Components of the data processing system. The main function of the data processing system is the implementation of typical data processing operations, which are:

Collection, registration and transfer of information to computer media;

Transfer of information to the places of its storage and processing;

Input of information into a computer, control of input and its arrangement in computer memory;

Creation and maintenance of an in-machine information base;

Information processing on a computer (accumulation, sorting, correction, sampling, arithmetic and logical processing) for solving functional problems of the object management system (subsystem);

Information output in the form of tabulagrams, videograms, signals for direct control of technological processes, information for communication with other systems;

Organization, management (administration) of the computational process (planning, accounting, control, analysis of the implementation of the course of computations) in local and global computer networks.

Data processing system (SOD) is intended for information service of specialists from various management bodies of the enterprise who make managerial decisions.

The selection of typical data processing operations made it possible to create specialized software and hardware systems that implement them (various peripheral devices, office equipment, standard sets of programs, including application software packages - PPP, - that implement the functional tasks of the IS). The configuration of hardware complexes forms the so-called the topology of the computing system.

SOD can operate in three main modes: batch, interactive, real time.

For batch mode it is characteristic that the processing results are issued to users after the execution of the so-called task packages. Examples of systems operating in batch mode include statistical reporting systems, tax inspectorates, cash settlement centers (RCCs), banks, etc. The disadvantage of this mode is the isolation of the user from the information processing process, which reduces the efficiency of making managerial decisions.

At interactive (dialogue) mode work is the exchange of messages between the user and the system. The user considers the results of the request and enters the decisions made into the system for further processing. Typical examples of dialogue tasks can be considered multivariate tasks of using resources (labor, material, financial).

Real time mode is used to control fast processes, for example, the transmission and processing of banking information in global international networks such as SWIFT, and continuous technological processes.

Almost all data processing systems of information systems, regardless of their scope, include the same set of constituent parts (components), called types of support (Figure 1.2). It is accepted to allocate information, software, technical, legal, linguistic support.

Information Support Is a set of methods and means for the placement and organization of information, including classification and coding systems, unified documentation systems, rationalization of workflow and document forms, methods of creating an in-machine information base of the information system. The quality of the developed information support largely determines the reliability and quality of management decisions.

Software- a set of software tools for the creation and operation of ODS by means of computer technology. The software includes basic (system-wide) and applied (special) software products.

Technical support is a complex of technical means used for the functioning of the data processing system both outside the computer (peripheral technical means for collecting, registering, primary processing of information, office equipment for various purposes, telecommunications and communication facilities), and on computers of various classes.

Legal support is a set of legal norms governing the creation and operation of an information system. Legal support for the development of an information system includes normative acts of contractual relationships between a customer and an IP developer. The legal support for the functioning of the ODS includes: the conditions for giving legal force to documents obtained with the use of computers; the rights, duties and responsibilities of personnel, including for the timeliness and accuracy of information processing; rules for the use of information and the procedure for resolving disputes over its reliability, etc.

Linguistic support is a set of language tools used at various stages of the creation and operation of ODS to improve the efficiency of development and ensure communication between humans and computers.

1.2.5 Organizational components of the information system. The allocation of organizational components in an independent direction is due to the special importance of the human factor (personnel) in the successful functioning of IS. Before implementing an expensive data processing system; a huge amount of work must be done to streamline and improve the organizational structure of the facility; otherwise, the efficiency of the IP will be low. the main problem at the same time, it consists in identifying the degree of correspondence between the existing management functions and the organizational structure that implements these functions and the company's development strategy. The means of achieving the goal - improving organizational structures - are various modeling methods.

Under organizational components of IP (Fig. 1.2) is understood as a set of methods and tools that make it possible to improve the organizational structure of objects and management functions performed by structural divisions; determine the staffing table and the number of members of each structural unit; to develop job descriptions for the management personnel in the conditions of the functioning of the ODS.

1.2.6 Trends in the development of information systems. The logic of the development of IP in the last 40 years clearly demonstrates the pendulum effect: the centralized data processing model based on mainframes, which dominated until the mid-80s, in just a few years gave way to the distributed architecture of peer-to-peer local area networks (LANs) of personal computers, but then a return movement towards the centralization of system resources.

Today, the focus is on client-server technology, which effectively combines the strengths of its predecessors.

There are several generations of IP.

First generation of IC (1960–1970) was built on the basis of central computers on the principle of "one enterprise - one processing center", and the IBM operating system - MVS - served as a standard environment for executing applications (functional tasks).

Second generation of IC (1970-1980): First steps towards decentralization of IP, in which users began to promote information technology in offices and branches of companies using mini-computers such as DEC VAX. At the same time, active introduction of high-performance DBMS like DB2 and packages of commercial application programs began. Thus, the cardinal innovation of this generation of ISs has become a two- and three-level model of organizing a data processing system (central computer - minicomputers of departments and offices) with an information foundation based on a decentralized database and application packages.

Third generation of IP(1980 - early 1990): A boom in distributed network processing driven by the massive shift to personal computers (PCs). The logic of corporate business demanded the unification of disparate workplaces into a single IS - computer networks and distributed processing appeared. Very soon, however, peer-to-peer networks began to show the first signs of hierarchy: first in the form of dedicated file servers, print and telecommunication servers, and then application servers. At some stage, the growing need for the concentration of IS resources responsible for system administration (organization of the computing process), support of the corporate database and the execution of centralized applications associated with it, was satisfied in the so-called "medium-sized" model through the use of UNIX servers , produced by IBM, DEC, Hewlett-Packard, Sun, etc. Therefore, the server market has become one of the most dynamic sectors of the computer industry.

With the development of third-generation ISs, the idea of ​​pure (peer-to-peer) distributed processing has noticeably faded and gave way to a hierarchical client-server model.

The fourth generation of IP. The distinctive features of modern ISs are, first of all, a hierarchical organization, in which centralized processing and unified management of IS resources at the upper level is combined with distributed processing at the lower level, determined by the synthesis of solutions tested in systems of previous generations. Information systems of the fourth generation accumulate the following main features:

Full utilization of the potential of desktop computers and the distributed processing environment;

Modular system design, assuming the existence of many different types of architectural solutions;

Saving system resources by centralizing data storage and processing at the upper levels of the IS hierarchy;

Availability of effective centralized means of network and system administration (organization of the computing process), allowing end-to-end control over the functioning of the network and management at all levels of the hierarchy, as well as providing the necessary flexibility and dynamic change in the system configuration;

A sharp decrease in the so-called "hidden costs" - operating costs for the maintenance of IS, which are not easy to foresee in the organization's budget (maintaining the functioning of the network, backing up user files on remote servers, configuring workstations and connecting them to the network, ensuring data protection, updating versions software, etc.).

1.3 Classification and structure of technical means of information technology

1.3.1 Stages of information systems operation

1.3.2 Basic information about the computer device

1.3.3 Computer classification

1.3.4 Trends in the development of computers

Literature: 2 p. 48–76; 4 c. 32-73; 5 c. 45-56; 6 c. 4-12, 92-136; 8.9.

1.3.1 Stages of information systems. In the work of the information system, in its technological process, several rather clearly distinguishable stages can be distinguished:

1. The origin of data, i.e., the formation of primary messages that record the results of business operations, properties of objects and subjects of management, parameters of production processes, the content of regulatory and legal acts, etc.

2. Accumulation and systematization of data , that is, the organization of such data placement, which would ensure a quick search and selection of the necessary information, methodical updating of data, their protection from distortion, loss, loss of connectivity, etc.

3. Data processing - processes, as a result of which, on the basis of previously accumulated data, new types of data are formed: generalizing, analytical, advisory, forecast ... Derived data can also be subjected to further processing and bring information of deeper generalization, etc.

4. Displaying data - presentation of data in a form suitable for human perception. First of all, this is printing, that is, the production of documents that are convenient for human perception. But such types of representation as the construction of graphic illustrative materials (graphs, diagrams) and the formation of sound signals are also widely used.

1.3.2 Basic information about the computer device. An electronic computing machine (computer) is a device that performs the following operations:

Information input;

Information processing according to the program embedded in the computer;

Output of processing results in a form suitable for human perception.

A special computer unit is responsible for each of these actions, respectively: an input device, a central processing unit (CPU), an output device. They are all very complex and, in turn, consist of separate smaller devices. In particular, the central processor may include: an arithmetic logic unit, a control unit, a random access memory. Thus, the enlarged structural diagram of the computer takes the form shown in Fig. 1.4. This composition was first formulated by the American mathematician of German origin John von Neumann (although it was first used during the Second World War by the German Konrad Zuse in his Z-series calculators).

Arithmetic logic unit (ALU) is exactly where the data transformations prescribed by the program commands are performed: arithmetic operations on numbers, code transformations, word comparisons, etc.

Random access memory (RAM), or just memory, is intended to accommodate programs, as well as to temporarily store some parts of the input data and intermediate results. It is characterized by: the ability to write (or read) elements of programs and data to an arbitrary memory location (or from an arbitrary memory location), high performance. Word arbitrary does not mean "just any", but the ability to refer to given address without the need viewing of all previous.

Figure 1.4 - Enlarged structural diagram of a computer

Computer quality characterized by many indicators. This is a set of instructions (commands) that a computer is able to understand and execute, and the speed (speed) of the central processor, and the number of input-output devices (peripheral devices) that can be connected to it at the same time, and power consumption, and much more. But the main characteristic, as a rule, is speed , that is, the number of operations that the central processor is capable of performing per unit of time.

The speed of the computer depends significantly on the speed of the RAM, or in other words, on the duration of access to the RAM. Therefore, we are constantly looking for RAM elements that would require as little time as possible for read-write operations. However, along with the speed, the cost of memory elements grows (and very sharply), so building RAM of the required capacity on fast elements is economically unacceptable. This issue was resolved by building tiered memory ... RAM consists of two or three parts: the main part of the large capacity is built on relatively slow (but cheaper) elements, and the additional part (it is called cache memory ) consists of high-speed elements. The data most frequently accessed by the ALU is in the cache; a larger amount of operational information is stored in the main memory. The distribution of information between the constituent parts of the RAM is controlled by a special unit of the central processing unit (CPU). The amount of RAM and cache memory is one of the most important characteristics of a computer.

1.3.3 Classification of computers. The range of types of computers is currently huge: machines differ in purpose, power, size, used element base, resistance to adverse conditions, etc. So it would be possible to classify computers from different points of view, according to different classification criteria. The currently accepted gradation of computers in terms of performance and overall characteristics (dimensions, weight) is presented in Table 1.1. It should be noted that the classification is to a certain extent arbitrary, since the boundaries between groups are blurred and very mobile in time: the development of this branch of science and technology is so rapid that, for example, today's micro-computer is not inferior in power to a mini-computer five years ago.

Table 1.1 - Classes of modern computers

Computer class	Main purpose	Basic technical data
Super-computer	Complex scientific calculations	Integral performance up to hundreds of billions of operations per second; hundreds of parallel processors
Mainframes (mainframes)	Processing large volumes of information from banks, large enterprises	Multiprocessor architecture; connection of up to 200 workplaces
Mini-computer	Medium-sized enterprise management systems; multi-console computing systems	Multiprocessor architecture, branched peripherals
Servers	Control of a local network or Internet site, data storage	One (many) processor architecture, high processor speed; large RAM, large capacity of hard disk drives
Workstations	Computer-aided design systems, experiment automation systems	One (many) processor architecture, high processor speed; large RAM, large capacity hard disk drives, specialized peripherals
Microcomputer	Individual user service; work in local automated control systems	Single-processor architecture, configuration flexibility - the ability to connect a variety of external devices

Class of personal computers itself is made up of very diverse types of machines and therefore deserves a separate classification (Table 1.2). Weight and dimension data were taken as a classification criterion.

Table 1.2 - Micro-computers (personal computers)

Type of

Weight, kg

Power supply

Stages of development of information systems

With the development and improvement of computer technology, programming languages ​​and software, automated data processing systems have undergone several stages of development. In the early days, computers performed cumbersome calculations instead of humans when solving numerical problems. In this case, large amounts of memory were not required, and the programming languages ​​used were focused on working with numerical data and performing engineering calculations.

Table 1. Changing the approach to the use of information systems

Time period	Information use concept	Type of information systems	Purpose of use
1950 - 1960	Paper flow of settlement documents	Information systems for processing settlement documents on electromechanical accounting machines	Increasing the speed of document processing. Simplified invoice processing and payroll processing
1960 - 1970	Essential help in preparing reports	Management information systems for production information	Speeding up the reporting process
1970 - 1980	Management control of implementation (sales)	Decision support systems. Systems for senior management	Selection of the most rational solution
1980 - 2000	Information is a strategic resource that provides a competitive advantage	Strategic information systems. Automated offices	Survival and prosperity of the firm

The first information systems appeared in the 50s. During these years, they were designed for processing invoices and calculating salaries, and were implemented on electromechanical accounting machines. This led to some reduction in costs and time for preparing paper documents.

60s are marked by a change in attitudes towards information systems. The information obtained from them began to be used for periodic reporting in many ways. To do this, organizations needed general-purpose computer equipment capable of serving a variety of functions, and not just processing invoices and calculating salaries, as was the case in the past.

In the 70s - early 80s. information systems are beginning to be widely used as a means of management control that supports and accelerates the decision-making process.

By the end of the 80s. the concept of using information systems is changing again. They become a strategic source of information and are used at all levels of an organization of any profile. Information systems of this period, providing the necessary information on time, help the organization to achieve success in its activities, create new products and services, find new sales markets, provide worthy partners for itself, organize the release of products at a low price and much more.

Comparison of information systems with traditional software products

Although information systems are a common software product, they have a number of significant differences from standard applications and systems.

Depending on the subject area, information systems can vary greatly in their functions, architecture, and implementation. However, a number of properties can be distinguished that are common:

· Information systems are designed to collect, store and process information. Therefore, any of them is based on the data storage and access environment;

· Information systems are oriented towards the end user who is not highly qualified in the field of computer technology. Therefore, client applications of the information system should have a simple, convenient, easy-to-learn interface that provides the end user with all the functions necessary for work, but at the same time does not allow him to perform any unnecessary actions.

Thus, when developing an information system, two main tasks have to be solved:

· The task of developing a database for storing information;

· The task of developing a graphical user interface for client applications.

The main components of corporate information systems

As part of corporate information systems, two relatively independent components can be distinguished:

· Computer infrastructure of an organization, which is a combination of network, telecommunication, software, information and organizational infrastructures. This component is commonly referred to as the corporate network.

· Interconnected functional subsystems that ensure the solution of the organization's problems and the achievement of its goals.

The first component reflects the systemic, technical, structural side of any information system. In fact, this is the basis for the integration of functional subsystems, which completely determines the properties of the information system, which determine its successful operation. The requirements for a computer infrastructure are uniform and standardized, and the methods for its construction are well known and have been repeatedly tested in practice.

The second component of the corporate information system is entirely related to the application area and strongly depends on the specifics of the tasks and goals of the enterprise. This component is completely based on the computer infrastructure of the enterprise and determines the applied functionality of the information system. Requirements for functional subsystems are complex and often contradictory, since they are put forward by specialists from various applied areas. However, in the end, it is this component that is more important for the functioning of the organization, since the computer infrastructure is actually being built for it.

The relationship between the components of the information system

The interrelationships between these two components of the information system are quite complex. On the one hand, these two components are independent in a sense. For example, the organization of the network and the protocols used to exchange data between computers are absolutely independent of what methods and programs are planned to be used in the enterprise for organizing accounting.

On the other hand, these components, in a certain sense, are nevertheless dependent on each other. Functional subsystems, in principle, cannot exist without a computer infrastructure. At the same time, the computer and infrastructure itself is rather limited, since it does not have the necessary functionality. It is impossible to operate a distributed information system in the absence of a network infrastructure. However, with a well-developed infrastructure, it is possible to provide employees in an organization with a number of useful system-wide services (for example, e-mail access to the Internet) that make work easier and more efficient (in particular, through the use of more advanced communications).

Thus, it is advisable to start the development of an information system with the construction of a computer infrastructure (corporate network) as the most important component based on proven industrial technologies and guaranteed to be implemented within a reasonable time frame and due to a high degree of certainty both in the formulation of the problem and in the proposed solutions.

It makes no sense to build a corporate network as a kind of self-sufficient system, without taking into account the application functionality. If, in the process of creating a system and technical infrastructure, analysis and automation of management tasks are not carried out, then the funds invested in the development of a corporate network will not give a real return later.

A corporate network is being created for many years to come, the capital costs for its development and implementation are so high that they practically exclude the possibility of complete or partial alteration of the existing network. Functional subsystems, in contrast to the corporate network, are changeable in nature, since more or less significant changes are constantly taking place in the subject area of ​​the organization's activities. The functionality of information systems strongly depends on the organizational and managerial structure of the organization, its functionality, the distribution of functions, financial technologies and schemes adopted in the organization, the existing workflow technology and many other factors.

The development and implementation of functional subsystems can be done gradually. For example, first, in the most important and critical areas, carry out developments that provide the applied functionality of the system (implement financial accounting systems, personnel management, etc.), and then distribute applied software systems and other, initially less significant areas of enterprise management.

Lecture 1.

Information system concept. IP classification. Project and design concept. Introduction to the methodology of building information systems. Objects and subjects of IP design.

Classification of methods and means of designing IS. The main objectives of the course

1.1. Information system concept

To determine the composition and structure of systems and, in particular, information systems, we present the basic concepts (slide 2) .

System- a set of interrelated elements that form a certain integrity.

System integrity- manifestation of the property emergence, reflecting the fundamental irreducibility of the properties of the system to the sum of the properties of its individual elements, and at the same time the dependence of the properties of each element on its place and function within the system.

System element - part of the system that has a specific functional purpose. In this case, a separate element of a system (like the system itself) can also be an element of another system. Complex elements of systems, in turn consisting of interconnected simpler elements, are called subsystems.

System structure - composition, order and principles of interaction of system elements, which determine the basic properties of the system. Structure - this is the part of the properties that remains unchanged in the system when its state changes.

System architecture - a set of properties of a system that are essential for organizing the interaction of its components.

The systems differ significantly from each other both in composition and in goals. Examples of systems consisting of different elements and aimed at achieving different goals are presented on slide 3 .

Information System (IS) Is a complex consisting of an information fund, as well as means, methods used for storing, processing and issuing information in order to achieve the set goal (slide 4) .

Obviously, many elements of the system (see. slide 4 ) are optional. For example, an object model may be absent or identified with a database (DB), which is often interpreted as domain information model- structural (for the case tabular, factual DB) or meaningful (for the case documentary databases). The object model and the database may be absent (and, accordingly, the processes of storing and retrieving data) if the system dynamically transforms information and generates output documents, without saving the original, intermediate, resulting information. But note that if and data conversion is also missing, then such an object is not an IS (it does not perform information activities), and therefore it should be classified as belonging to other classes of systems (for example, an information transmission channel, etc.). The data entry and collection processes are also optional because all necessary and sufficient for the functioning of the AIS, information may already be in the database and the composition of the model, etc.

The given definition of an information system is associated with the usual, but, nevertheless, a special form of purposeful human activity - information processing, which ensures an increase in the efficiency of solving the problems of his main activity. The concept of "consistency" is present here implicitly and reflects the essence of functionality: the composition and structure of the IS is determined based on the requirements for the level service efficiency of information needs, primarily in terms of finding and processing those records of the information fund that contain information necessary for effective execution and management of processes in the field of core business. Thus, the information system has the following properties (slide 4) :

any information system can be analyzed, built and managed on the basis of general principles of building systems;

the information system is dynamic and evolving;

when building an information system, it is necessary to use a systematic approach;

an information system, one way or another, should be perceived as a man-machine system.

Information as the main object of IS processing

Since the main object and product of the functioning of IS is information, it is necessary to define the concepts of "data" and "information";

The constructiveness of such a definition consists not so much in declaring that context is and it must be used (processed), how much is that the system beret data (signals, quantities, etc.) from an infinite set of environmental data. Hence, need to choose only those that fit the context, i.e. necessary and sufficient to solve a specific problem... Obviously, the data in this case should have, or rather (due to the elementary (atomic) nature of what is called "given") should be associated with a context, which is usually given in the form of a set of distinctive features, which, in turn, also represent some set of data. Further, for some targeted processing, this data is processed by an application program (the data is associated with a processing method, which is one of the forms of setting the context) and, as a result, the result obtained (also data) must be associated with the method of its use, which will ensure the effectiveness of information for " end user "in reality.

Hence follows an important conclusion, which predetermines not only the differences between IS and DBMS, but also approaches to the design of systems for automated information processing: IS, in addition to means of data transformation, one way or another, has means of storing and processing the context (in this case, the context is, of course, also data, but performing the role of metadata - data on the nature of the data being processed), including as an independent object.

If the purpose of information systems were only storage and retrieval of data in arrays of records, then the structure of the system and database would be simple. The reason for the complexity is that almost any object is characterized not only by parameters-quantities, but also by the interconnections of parts or states. In addition, as noted above, a separate data element (quantity) itself acquires meaning (meaning) only when it is associated with the nature of the meaning (respectively, with other data elements), which will allow it to be interpreted.

Therefore, the physical layout of data (and, accordingly, the definition of the structure of the physical record) should be preceded by a description of the logical structure of the subject area - the construction model the corresponding fragment of the real world, which selects only those objects that will be of interest to future users, and represented only by those parameters that will be significant in solving applied problems. Such a model will have very little physical resemblance to reality, but will be useful as performance user about the real world. Moreover, this representation will be set for inadequate for a person hard computing environment with a numerical representation of information, but described user friendly means.

This approach is a compromise: at the expense of predefined set of abstractions common to most data processing tasks, it is possible to build reliable processing programs. User using limited set of formal, but fairly familiar concepts highlighting entities and relationships, describes the objects and relationships of the subject area; programmer using such typical abstract concepts(such as numbers, sets, data aggregates) defines the corresponding information structures. Data management system using binary representations typed data, provides effective procedures for storing and processing data.

With any method of displaying a subject area in machine databases (DB), the display is based on the fixation (coding) of concepts and relations between concepts. Abstract concept structures is closest to the so-called conceptual model of the subject environment and often underlies the latter.

The concept of structure is used at all levels of the domain representation and is implemented as:

information structure- a schematic form (providing a transition to an attributive form) of representing complex compositional objects and connections of a real subject area (SbA), identified as actually necessary for solving applied problems, in the general case, without taking into account whether programming tools and computers will be used to solve it ... Efficiency here is determined by the level of abstraction, as well as the completeness and accuracy of the representation of properties through the selected system of characteristics;

data structure- an attributive form of representation of SbA properties and relationships, focused on the expression of data description by means of formal languages ​​(i.e., taking into account the capabilities and limitations of specific means in order to reduce descriptions to standard types and regular relationships). Efficiency in this case is associated with the process of building a program ("solver" of an applied problem) and, in a sense, with the effectiveness of the programmer's work;

structure of records- expedient (taking into account the peculiarities of the physical environment) implementation of methods for storing data and organizing access to them both at the level of individual records and their elements. Efficiency in this case is associated with the exchange processes between RAM and external memory devices and is provided by data redundancy artificially introduced to ensure the functional efficiency of individual operations (for example, search by keys).

The main components of the IC(slide 6)

The main and defining component of any information system are functionally interconnected data sets and procedures their processing. Note that these complexes, either individually or together, do not yet create the same integrity, which is inherent in systems. Systemic properties are manifested when IS is considered in the dynamics of interrelation with the environment, i.e. when the factors of controllability and adaptability to changing external conditions, stability over time become essential. That is why any system, in addition to functional components - the main ones from the point of view of the purpose of the system, must include organizational and supporting components, the purpose of which is to create the necessary conditions for functioning, including the formation of control subjects. In turn, IP is an integral part of some larger system that ensures the achievement of a specific goal in human activity.

Functional subsystems they implement and support models, methods and algorithms for information processing and the formation of control actions within the framework of the problems of the subject area, i.e. the composition and purpose of functional subsystems depends on the subject area of ​​the features of using the IS. On (slide 6) some areas are listed whose functionality seems fairly obvious. We only note that the subsystem information support one way or another, it is part of any activity, since it is it that determines the quality of research (including marketing) work, design and technological preparation of production.

Composition supporting subsystems is quite stable and usually depends little on the subject area of ​​the use of IP. Let's note the following components:

information support (information fund), a set of data that determine not only practically significant (target) information, but also ways of organizing it ( meta information), as well as the form of presentation;

technical support- physical components of the system, such as external memory, technical and computing facilities, providing direct processing and interaction of the user with the IC;

software- a set of software components for regular use, necessary to solve functional tasks and programs that allow the most efficient use of computing technology, providing users with the greatest convenience in their work;

software- a set of methods, models and algorithms for functional (target) information processing used in the system;

linguistic support(LO) Is a set of linguistic tools that provide flexibility and multilevel presentation and processing of information in AIS. Usually LO includes languages ​​of queries and reports, special languages ​​of definition and data management, ensuring the adequacy of the internal representation and the coordination of internal and external representations. LO is most dependent on the characteristics of the subject area.

Organizational subsystems also refer to supporting, but are primarily aimed at ensuring the effective work of personnel and the system as a whole, therefore, they can be singled out separately. Note that the development of an IS should begin precisely with organizational support: justification of the feasibility of the system, economic indicators that determine its activities, the composition of functional subsystems, the organizational structure of management, technological schemes for converting information, the procedure for carrying out work, etc.

Programs and games