When designing an information system, determine. Building a data model. Information system profile concept

1.2 Stages of design of information and reference systems

Designing an information and reference system is one of the most important stages of its existence, something from which, in fact, its life should begin. Any correct information and reference system is based on a carefully designed database, which takes into account not only all the features of doing business, but also provides for the possibility of future development by adding functionality to the information system.

The task of designing AIS for industrial enterprises is rather difficult, since the nature of the processed information is heterogeneous and difficult to formalize. However, here we can distinguish the main model of work - it is work "from the project code". V general case the project code is an analogue (functional) of a personal account, it has a certain bit depth, order (i.e. a specific group of alphanumeric designations characterizes a part, assembly unit, product and their level of interconnection). Moreover, a specific part of the code characterizes technological, design, financial and other documents. All this is regulated by the relevant GOSTs, so it can be formalized. In this case, a modular approach to the implementation of AIS is most important.

A dual approach to shaping the daily production plan formed the basis of the so-called. "principle of dualism" for AIS industrial enterprises. The implementation of the principle of dualism inevitably also required the construction of AIS enterprises of a new generation in the form of software modules, organically interconnected, but, at the same time, capable of working autonomously.

Such a multicomponent system ensured compliance fundamental principle construction of automated information systems - no duplication of input of initial data. Information on operations carried out using one of the components of the system could be used by any other component of the system. The modularity of the construction of a new generation of AIS and the principle of one-time input make it possible to flexibly vary the configuration of these systems.

In addition, one of the advantages of the multicomponent principle, which is basic in the creation of a new generation of AIS, is the possibility of their phased implementation. At the first stage of implementation, outdated system components are installed (or replaced) on those workstations that need software updates. At the second stage, the development of the system takes place with the connection of new components and the development of inter-component connections. The possibility of using this implementation methodology ensures its fairly simple replication and adaptation to local conditions. Thus, a new generation automated information system is a multicomponent system with a distributed database by levels of expertise.

Many enterprises prefer to develop AIS on their own, because:

1.the cost of such developments is relatively low (in comparison with the products of large foreign developers). As a rule, only a new structure is added to the existing subdivisions of the informatization department, such as: operation management, management of computer network and communication facilities, expert and analytical management (setting tasks), only a new structure is added: the management of development and development of AIS, which, as a rule, does not entail for a large financial cost.

2. own development is the maximum focus on the implementation of business processes of an enterprise or a bank, its unique financial and management technologies, which have been taking shape over the years.

3.This allows for a significantly higher level of security and independence from external factors.

4. a prompt reaction to changes in the rules of the game on the market is possible.

At the same time, with its own development, it is necessary to solve a whole range of organizational and technical problems that would make it possible to avoid erroneous decisions:

At first, right choice architecture of building a computing and communication network and focus on professional DBMS. According to expert estimates, 53% of our own AIS developments are based on Oracle DBMS, about 15% on Informix, and 22% on other DBMSs.

Secondly, the use of modern tools in the development.

Thirdly, a multitasking infrastructure for project development, when a specific AIS module is managed by a group of developers with an interconnected list of tasks, built on the principles of complete interchangeability, i.e. the functioning of this AIS module and its development is not associated with one specific developer.

Fourth, the use of effective organizational and technical means for project management and AIS version control.

Only if these basic provisions are observed can we expect that our own development will be competitive and effective. Otherwise, you can face the effect of "unjustified expectations" - this is at best, and in extreme cases, generally think about changing the AIS. At the same time, the change of the AIS can cause both a direct change of client modules and the tabular structure of the database, and require the replacement of the server and client hardware and system-wide software, including the DBMS, and this business is not cheap. Therefore, when choosing an AIS implementation option, it is very important to immediately resolve the issue of data export / import capabilities in the system being created. With the right decision this issue the change of the AIS, if it is nevertheless necessary, will happen almost painlessly for the functional units.

Unlike banking structures, large domestic industrial enterprises now they are just approaching the realization of the clear need for the implementation and development of corporate information systems as one of the main components strategic development business. In this regard, in the near future, we can expect the expansion of the market for corporate information systems and its subsequent significant growth. Given the close integration of financial and industrial structures it can be assumed that the basis of construction corporate systems financial and industrial groups will be, used in their financial institutions, ABS.

Focusing on professional DBMS can help achieve the following goals:

1) Optimized multi-user mode of operation with a developed system of transactional processing, which provides numerous users with the ability to work with the database without interfering with each other.

2) Reliable means of information protection (taking into account the standard three-tier architecture of protection at the network level - at the database server level - at the client OS level).

3) Effective tools to differentiate access to the database.

4) Support for a wide range of hardware and software platforms.

5) Implementation of distributed data processing.

6) Ability to build heterogeneous and distributed networks.

7) Advanced tools for management, control, monitoring and administration of the database server.

8) Support for such effective tools as: data dictionaries, triggers, functions, procedures, packages, etc.

All of the above has led to the widespread use of solutions based on professional DBMS in large commercial banks and industrial corporations. According to expert estimates, Oracle, Informix, and Sybase are leading in the number of installations. Despite this, in most medium and small banks and enterprises, they still focus on solutions based on the third and even second generation AIS.

The main reasons for focusing on the use of professional DBMS when building your own AIS:

"AGAINST" - Relatively high cost of professional DBMS

"FOR" - As a rule, suppliers of almost all professional DBMSs now offer scalable solutions for medium and small systems, and the price of the latter is comparable to the prices for local DBMS.

"CONS" - Professional DBMS make high demands on the hardware platform.

"FOR" - With a sharp increase in the performance of Intel-oriented hardware platforms, most manufacturers of professional DBMS have released their versions for Intel-servers, including the Linux OS, and given that LINUX, with all its UNIX system power, is practically a free OS, then a solution based on it, as a rule, will not entail large financial costs. This allows, when building a system, to focus not only on high-performance multi-cluster RISC servers, but also to use Intel server platforms.

"CONS" - Professional AIS is difficult and expensive to administer.

"FOR" - As a rule, the complexity of administration depends on the specific AIS. In addition, when operating AIS in a multidisciplinary bank or enterprise on a UNIX platform, it removes many problems that arise in the field, due to the wide possibilities of remote administration from the center.

"CONS" - Development of AIS on an industrial platform is too expensive.

"FOR" - Designing modern integrated systems is a laborious process that requires highly qualified developers. All this is reflected in the price and objectively makes the new generation AIS more expensive, but still comparable in cost to their predecessors.

"AGAINST" - Implementation of systems on a professional platform is a lengthy and expensive process.

"FOR" - The delay in implementation, as a rule, is caused either by the lack of experience of the supplier's company in installing such systems, or by insufficient readiness of the product being implemented. The approximate period of installation of a typical AIS of the fourth generation under Oracle DBMS with a streamlined technological process is several weeks.

"CONS" - Maintenance of systems based on a professional platform is unreasonably expensive, and the quality characteristics of such AIS leave much to be desired.

"FOR" - In many ways, this prejudice has developed on the basis of the experience of operating foreign-made AIS. It is possible to indicate a number of cases when foreign supplier firms either refused to make timely changes due to the new instructions of the Central Bank, or demanded unreasonably large sums for these changes. However, this does not apply at all to domestic systems of a new generation, originally designed for a changeable Russian legislation.

Market analysis shows that today a modern AIS should be an integrated complex of hardware and software tools implementing a multi-subject information system that provides modern financial, managerial, design, production and sales technologies in real time in transactional data processing.

What are the main distinguishing features of corporate DBMS. First, they were initially aimed at creating integrated, multi-user systems, having at their disposal developed data dictionaries, which significantly increases the role of systems analysis and modeling in system design. Second, the development tools for these DBMS are optimized for the collective development of complex systems within a single well-thought-out strategic line. All this determines the steadily growing number of successful implementations of systems based on professional DBMS.

So, after choosing the method that should guide the design information system, it is necessary to plan a complex of works on the creation of IS in accordance with the typical stages of development. The stages of development of automated information systems in the classical version will look like this.

A) Development and analysis of a business model

The main tasks of the AIS are determined, the tasks are decomposed into modules and the functions are determined with the help of which these tasks are solved. The description of functions is carried out in the language of production (description of the processes of the subject area), functional (description of the forms of processed documents) and technical requirements(hardware, software, linguistic AIS). Solution method: Functional modeling. Result:

AIS conceptual model, consisting of a description of the subject area, resources and data streams, a list of requirements and restrictions for the technical implementation of AIS.

Hardware and technical composition of the created AIS.

B) Formalization of the business model, development of a logical model of business processes.

The developed conceptual model is formalized, i.e. is embodied in the form of a logical AIS model. Solution method: Development of an entity-relationship (ER (Entity-Reationship) - CASE-diagram) diagram. Result: Developed AIS information support: diagrams and data structures for all levels of AIS modularity, documentation on the logical structure of AIS, generated scripts for creating database objects.

C) Selection of linguistic support, development of AIS software.

AIS development: linguistic support is selected (development environment - tools), software and methodological support is being developed. The logical scheme developed in the second stage is embodied in real objects, while the logical schemes are implemented in the form of database objects, and functional schemes in user forms and applications. Solution method: Development of program code using the selected toolkit. Result: A workable AIS.

D) Testing and debugging AIS

On this stage correction of information, hardware, software is carried out, methodological support is being developed (documentation of the developer, user), etc. Result: Optimal composition and efficient functioning of the AIS. A set of documentation: developer, administrator, user.

E) Operation and version control

The peculiarity of the AIS created according to the client-server architecture is their multi-level and multi-modularity, therefore, during their operation and development, the issues of version control come to the fore, i.e. addition of new and development of old modules with the decommissioning of old ones. For example, if the daily version control is not carried out, then as practice has shown, the AIS database for a year of operation can number more than 1000 tables, of which only 20-30% will be effectively used. Result: Scalability and redundant composition of flexible, scalable AIS.

Figure 1.3 Sequence of transformation of the business model into database objects and applications

In this case, the sequence of transformation of the business model into database objects and applications will be as follows. The development of the main functions and purpose of the AIS and the modeling of the subject area precedes the study of the business processes of the resulting model and the formation of database objects. At the same time, at each stage, methods and means specific to it are used.

The work of database designers is highly dependent on the quality of the information model. The information model should not contain any obscure constructs that cannot be implemented within the framework of the selected DBMS. It should be noted that information model is created in order to build a data model on its basis, that is, it must take into account the implementation features of the selected DBMS. If certain features of the DBMS do not allow to reflect in the data model what the information model describes, then it is necessary to change the information model, since the manufacturer of the DBMS is unlikely to promptly change the DBMS itself for your specific project (although these are, however, isolated, cases took place).

Building logical and physical data models is an essential part of database design. The information model obtained during the analysis is first transformed into a logical and then into a physical data model. After that, a trial database is created for the developers of the information system. Code developers start working with it. Ideally, by the time development starts, the data model should be robust. Database design cannot be divorced from module and application design, since business rules can create objects in the database, such as server constraints, as well as stored procedures and triggers - in this case, it is often said that part of the business logic transferred to the database. Designing a data model for each DBMS contains its own characteristics, design decisions that give a good result for one DBMS, but may turn out to be completely unacceptable for another. The following are tasks that are common for designing data models:

Revealing unrealizable or unusual constructs in the ER model and in entity definitions;

Resolution of all arcs, subtypes and supertypes;

Study of possible, primary, foreign keys, description of referential integrity (depending on the implementation, declaratively or using triggers);

Design and implement database denormalization to improve performance;

Determination of the part of the business logic that should be implemented in the database (packages, stored procedures);

Implementation of constraints (constraints and triggers) reflecting all centrally defined business rules, generation of constraints and triggers;

Defining a set of business rules that cannot be specified as constraints in the database;

Determination of the required indexes, clusters (if they are implemented in the DBMS), determination of horizontal fragmentation of tables (if it is implemented in the DBMS);

Estimation of the sizes of all tables, indexes, clusters;

Determination of the size of table spaces and the peculiarities of their placement on information carriers, determining the specification of information carriers for industrial system(for example, the type of raid arrays, their number, what table spaces are located on them), determining the size of the required system table spaces (for example, the system catalog, transaction log, temporary table space, etc.);

Determination of database users, their access levels, development and implementation of access security rules, auditing (if necessary), creation of packaged privileges (depending on the DBMS implementation, these are roles or groups), synonyms;

Development of a database topology in the case of a distributed database, definition of mechanisms for accessing remote data.

Thus, a corporate information system is a set of technical and software tools of an enterprise that implement ideas and methods of automation. Modern systems business process management allows you to integrate various software around them, forming a single information system. This solves the problems of coordinating the activities of employees and departments, providing them with the necessary information and control. performing discipline, and the management receives timely access to reliable data on the progress of the production process and has the means to promptly make and implement their decisions. And, most importantly, the resulting automated complex is a flexible open structure that can be rebuilt and supplemented with new modules or external software.

An information system can be built using the layer-by-layer principle. So, in separate layers it is possible to distinguish specialized software (office, applied), directly workflow, document management system, programs for stream input of documents, as well as auxiliary software for communication with the outside world and providing access to the system functionality through communication means (e- mail, Internet / intranet).

The design stages of an information and reference system - one of the main components of the CIS - represent a consistent advance from the study of the subject area to the operation of the finished system. During the design process, it is necessary special attention to devote to the development of a data model at the conceptual, logical and physical levels.

CHAPTER 2. CHARACTERISTIC OF THE INFORMATION SYSTEM GOU NPO PU No. 33

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Stages of designing automated information systems. Two areas of activity are directly related to the design of AIS: 1) the actual design of AIS of specific enterprises (industries) on the basis of ready-made software and hardware components using special development tools; 2) the design of the mentioned AIS components and tools oriented to multiple use in the development of many specific information systems.

The essence of the first direction can be expressed by the words “system integration”. AIS developer must be a specialist in the field of systems engineering, have a good knowledge of international standards, state and development trends information technologies and software products, be proficient in application development tools (CASE-tools) and be ready to perceive and analyze automated application processes in cooperation with specialists in the relevant subject area. There are a number of firms specializing in the development of AIS projects (for example, Price Waterhouse, Jet Info, Consistent Software, etc.).

The second direction is more related to the field of development of mathematical and software for the implementation of AIS functions - models, methods, algorithms, programs based on knowledge of systems engineering, methods of analysis and synthesis of design solutions, programming technologies, operating systems etc. In each class of AIS (ACS, CAD, GIS, etc.) there are firms specializing in the development of software (and sometimes hardware and software) systems. Each of them advertises its own technology for creating AIS and adheres to the strategy of either a total supplier, or openness and expansion of the system with applications and additions from third parties.

Both, in fact, the AIS, and the components of the AIS are complex systems, and when designing them, it is advisable to use a top-down style of block-hierarchical design, which includes a number of levels and stages.

The upper level of AIS design is often referred to as conceptual design. Conceptual design is carried out in the process of pre-design research, formulation of a technical proposal, development of a preliminary design.

Prev design studies carried out by analyzing (surveying) the activities of the enterprise (company, institution, office) where the AIS is being created or modernized. Before the survey, the objectives of the survey are formed and in the process of its implementation - the definition of opportunities and resources to improve the efficiency of the enterprise on the basis of automation of management processes, design, and document flow. The content of the survey is the identification of the structure of the enterprise, the functions performed, information flows, experience and available automation tools. The survey is carried out by system analysts (system integrators) together with representatives of the customer organization.

Based on the analysis of the survey results, an initial AIS concept is developed. This concept includes proposals for changing the structure of the enterprise and the interaction of departments, for the choice of basic software and hardware, and the proposals must take into account the forecast for the development of the enterprise. With regard to hardware and especially software (software), such a choice is most often the choice of the company - the supplier of the necessary tools (or at least the basic software), since the correct joint work programs of different companies are achieved with great difficulty.

The results of the analysis - a technical proposal and a business plan for creating AIS - are presented to the customer for final approval.

Both at the survey stage and at subsequent stages, it is advisable to adhere to a certain discipline of fixing and presenting the results obtained, based on one or another method of formalizing the specifications. Formalization is needed to unambiguously understand the requirements, restrictions and decisions made by executors and customers.

In conceptual design, a number of specifications are used, among which models for the transformation, storage and transmission of information occupy a central place. The models obtained in the process of surveying an enterprise are models of its functioning. In the process of developing AIS models, as a rule, they undergo significant changes and in their final form they are considered already as models of the designed AIS.

Distinguish between functional, informational, behavioral and structural models. Functional model system describes the set of functions performed by the system. The information model reflects data structures - their composition and relationships. The behavioral model describes information processes (dynamics of functioning), it includes such categories as system state, event, transition from one state to another, transition conditions, sequence of events. The structural model characterizes the morphology of the system (its construction) - the composition of subsystems, their interrelationships.

The content of the subsequent stages of top-down design is the definition of lists of purchased equipment and finished software products, construction of a system environment, detailed infological design of databases and their initial content, development of our own original software, which, in turn, is divided into a number of stages of top-down design.

A special place in a number of design tasks is occupied by the development of a corporate computer network project, since the technical support of the AIS has a network structure.

If the AIS is located at points remote from each other, in particular, located in different cities, then the issue of leasing communication channels for corporate network, since the alternative use of a dedicated channel in most cases turns out to be unacceptable due to the high price. Naturally, in this case, first of all, the possibility of using Internet services is being considered. It is through the Internet that enterprises operating on the CALS technology (Computer Acquisition Life-Cycle System) can interact. The problems arising in this case are related to the provision of information security and the reliability of message delivery.

One of the main trends in the modern informatics industry is the creation open systems... The property of openness means, firstly, the portability (mobility) of software to various hardware platforms, and secondly, the adaptability of the system to its modifications (modifiability or openness itself) and integration with other systems in order to expand its functionality and / or give the system new qualities (integrability).

Stage I - pre-design (inspection, drawing up a report, feasibility study and terms of reference);

Stage II - design stage (drawing up technical and working projects);

Stage III - implementation (preparation for implementation, conducting pilot tests and putting into software operation);

Stage IV - functioning analysis (identifying problems, making changes to design solutions and existing AIS and AIT).

Fig. 1.

At the pre-design stage, the study and analysis of the design object is carried out. In particular, the information base, all input documents, their volume, frequency, algorithms, output documents and all information links of tasks are analyzed. This data is processed, and an information model of objects is built in the form of tables and graphs.

Methods for studying and analyzing the state of an economic object and its management system include:

oral and written survey;

written questionnaire;

observation, measurement, evaluation;

group discussion;

analysis of tasks;

analysis of production, management and information processes.

As a result of the survey, recommendations are made for changing the organizational structure, new job descriptions, the expediency of certain documents, the composition of databases, proposals for changing the processing technology are determined, the configuration of the computer network, the number of machines, the composition of economic tasks, the sequence of their computerization are determined, proposals are developed for the implementation of economic tasks by means of applied software packages.

At the design stage, technical and working projects are drawn up for each level of the workstation. The working draft reflects general provisions, composition of technical means, architecture, organizational structure in new conditions, the setting of tasks is being done, information support is being designed, information exchange with other AWPs, it is calculated economic efficiency, instructions for performers.

Designing technical processes includes the design of passwords, programs, scripts for the user-PVM dialogue, including the design of hierarchical organized menus and "windows." If ready-made packages of application programs are involved, then they must contain a user's manual for operation and a set of machine programs on diskettes.

The statement of the problem gives a comprehensive idea of ​​its essence, the logic of transforming the initial information to obtain a result.

In the process of setting the problem, the following are revealed:

its organizational and economic essence (name, purpose of the solution, frequency and timing of the solution, sources and methods of receiving data, consumers of result information and methods of sending it, information links with other tasks);

description of the initial variable and conditionally constant information (list, presentation forms, volume indicators, description of structural units of information, methods of controlling initial data);

description of the resulting information (list, presentation forms, users, structural units of information, control methods);

description of the algorithm for solving the problem (the sequence of performing arithmetic and logical operations).

Currently, almost all AIS are decentralized, so it is important for the user to participate in the pre-design stage, in the formulation and implementation of tasks, and in the analysis of the functioning of the AIT.

Life cycle of information systems

The development of a corporate information system, as a rule, is carried out for a very specific enterprise. The specifics of the subject activity of the enterprise will undoubtedly influence the structure of the information system. But at the same time, the structures of different enterprises are generally similar to each other. Each organization, regardless of its type of activity, consists of a number of divisions that directly carry out one or another type of company activity. And this situation is true for almost all organizations, no matter what type of activity they are engaged in.

The main phases of information system design

Each project, regardless of the complexity and amount of work required for its implementation, goes through certain states in its development: from the state when "the project is not yet" to the state when "the project is no longer there." The set of stages of development from the emergence of an idea to the complete completion of the project is usually divided into phases (stages, stages).

There are some differences in determining the number of phases and their content, since these characteristics largely depend on the conditions for the implementation of a particular project and the experience of the main participants. Nevertheless, the logic and the main content of the information system development process are in almost all cases the same.

The following phases of information system development can be distinguished:

1. concept formation. The main content of work in this phase is the definition of the project, the development of its concept, including:

Idea formation, goal setting;

Formation of a key project team;

Studying the motivation and requirements of the customer and other participants;

Collection of baseline data and analysis of the existing state;

Determination of the basic requirements and restrictions required material, financial and labor resources;

Comparative assessment of alternatives;

Submission of proposals, their examination and approval;

2. development of technical specifications. The main content of this phase is the development of a technical proposal and negotiations with the customer to conclude a contract. The general content of the work of this phase:

Development of the main content of the project, the basic structure of the project;

Development and approval of technical specifications;

Planning, decomposition of the basic structural model of the project:

Estimating and budgeting the project, determining the need for resources;

Development of schedules and enlarged work schedules;

Signing a contract with a customer;

Putting into operation the means of communication of the project participants and control over the progress of work;

3. design. At this phase, the subsystems, their interrelationships are determined, the most effective ways project execution and resource use. Typical works of this phase:

Performing basic design work;

Development of private technical specifications;

Conceptual design;

Drawing up technical specifications and instructions;

Performance design development, examination and approval.

At this stage, the issues of determining the input and output streams of information, their types, data protection tools, programs, and computer systems are resolved. At this moment, a data schema, action menu, system resource diagrams, program interactions, program diagrams are being developed:

· data schema graphically displays the path of data in solving problems from the moment of origin to transfer to the consumer and determines the stages of processing, as well as the used data carriers;

· action menu- this is a horizontal list of objects on the screen, representing a group of actions available to the user for selection;

· system resource diagram displays the configuration of data blocks and processing tools that are required to solve the problem;

· program scheme displays the sequence of operations in the program;

· program interaction scheme shows the path of activation of programs and interactions with the corresponding data;

· system operation diagram displays the management of operations and data flows and reflects technological process data processing in the system.

4. manufacturing. In this phase, coordination and operational control work on the project, manufacturing of subsystems, their integration and testing is carried out. Main content:

Implementation of software development work;

Preparing for the implementation of the system;

Control and regulation of the main indicators of the project.

5. system commissioning... In this phase, tests are carried out, trial operation of the system in real conditions, negotiations are underway on the results of the project and on possible new contracts. Main types of work:

Complex tests;

Personnel training for the operation of the system being created;

Preparation of working documentation, delivery of the system to the customer and putting it into operation;

Escort, support, service maintenance;

Assessment of project results and preparation of final documents;

Conflict resolution and project closure;

Accumulation of experimental data for subsequent projects, analysis of experience, state, determination of development directions.

The second and partially the third phases are usually called the phases of systems design, and the last two (sometimes this includes the design phase) - the phases of implementation.

The initial phases of the project have a decisive influence on the achieved result, since they make the main decisions that determine the quality of the information system. At the same time, usually 30% of the contribution to the final result of the project is made by the phases of the concept and proposals, 20% by the design phase, 20% by the manufacturing phase, 30% by the phase of delivery of the object and the completion of the project.

In addition, it takes about twice as long to find errors made in the systems engineering phase than in subsequent phases, and to fix them is five times more expensive. Therefore, in the early stages of a project, development should be carried out especially carefully. Most often, in the initial phases, following errors:

Errors in determining the interests of the customer;

Concentration on unimportant, third-party interests;

Wrong interpretation of the original problem statement;

Wrong or insufficient understanding of details;

Incompleteness of functional specifications (system requirements);

Errors in determining the required resources and timing;

A rare check for the consistency of stages and the lack of control on the part of the customer (there is no customer involvement).

Information systems design

The development of a corporate information system, as a rule, is carried out for a very specific enterprise. The specifics of the subject activity of the enterprise will undoubtedly affect the structure of the information system. But at the same time, the structures of different enterprises are generally similar to each other. Each organization, regardless of its type of activity, consists of a number of divisions that directly carry out one or another type of company activity. And this situation is true for almost all organizations, no matter what type of activity they are engaged in.

Thus, any organization can be considered as a set of interacting elements (subdivisions), each of which can have its own rather complex structure. The relationships between departments are also quite complex. In the general case, one can distinguish three types of connections between divisions of the enterprise:

 functional connections - each department performs certain types of work within the framework of a single business process;

 informational communications - departments exchange information (documents, faxes, written and oral orders, etc.);

External relations - some departments interact with external systems, and their interaction can also be both informational and functional.

The generality of the structure of different enterprises allows us to formulate some common principles of building corporate information systems.

In general information system development process can be considered from two points of view:

 in terms of the main work streams: performers, actions, sequence of actions, etc .;

 by time, or by stages life cycle the system being developed. In this case, the dynamic organization of the development process is considered, described in terms of cycles, stages, iterations and stages.

An enterprise information system is being developed as a kind of project. Many features of project management and project development phases (life cycle phases) are general, not depending not only on the subject area, but also on the nature of the project (it does not matter if it is an engineering project or an economic one). Therefore, it makes sense to first consider a number of general project management issues.

A project is a time-limited, purposeful change of an individual system from an initial clear specific goals the achievement of which determines the completion of the project, as well as with the established requirements for the timing, results, risk, the framework for spending funds and resources, and for the organizational structure.

Usually for a complex concept (which, in particular, is the concept of a project) it is difficult to give an unambiguous formulation that fully covers all the features of the concept being introduced. Therefore, the given definition does not claim to be unique and complete.

The following can be distinguished main distinguishing features of the project as a control object:

Variability - purposeful transfer of the system from the existing to some

the desired state, described in terms of the goals of the project;

• limitation of the ultimate goal;

Limited duration;

 limited budget;

 limited resources required;

 novelty for the enterprise for which the project is being implemented;

• complexity - the presence of a large number of factors that directly or indirectly affect the progress and results of the project;

 legal and organizational support - creation of a specific organizational structure for the duration of the project.

Work efficiency is achieved by managing the project implementation process, which ensures the allocation of resources, coordination of the work sequence and compensation of internal and external disturbances.

From the point of view of the theory of control systems, a project as a control object must be observable and manageable, that is, some characteristics are distinguished by which it is possible to constantly monitor the progress of the project (the property of observability). In addition, mechanisms of timely influence on the course of project implementation are required (the property of controllability).

The property of controllability is especially important in conditions of uncertainty and variability of the subject area, which often accompany projects for the development of information systems.

Each project, regardless of the complexity and scope of work required for its implementation, goes through certain states in its development: from the state when "the project is not yet" to the state when "the project is no longer there." The set of stages of development from the emergence of an idea to the complete completion of the project is usually divided into phases (stages, stages).

There are some differences in determining the number of phases and their content, since these characteristics largely depend on the conditions for the implementation of a particular project and the experience of the main participants. Nevertheless, the logic and the main content of the information system development process are in almost all cases the same.

The following phases of information system development can be distinguished:

 concept formation;

 development of technical specifications;

 design;

 manufacturing;

 putting the system into operation.

Let's consider each of them in more detail.

The second and partially the third phases are usually called the phases of systems design, and the last two (sometimes this includes the design phase) - the phases of implementation.

Conceptual phase

 idea formation, goal setting;

 formation of the key project team;

 study of the motivation and requirements of the customer and other participants;

 collection of initial data and analysis of the existing state;

 determination of basic requirements and restrictions, required material, financial and labor resources;

 comparative assessment of alternatives;

 submission of proposals, their examination and approval.

Development of a technical proposal

 development of the main content of the project, the basic structure of the project;

 development and approval of technical specifications;

 planning, decomposition of the basic structural model of the project;

 drawing up the estimate and budget of the project, determining the need for resources;

 development of schedules and enlarged work schedules;

 signing a contract with a customer;

 putting into operation the means of communication of the project participants and control over the progress of work.

Design

At this phase, subsystems, their interconnections are determined, the most effective ways of project execution and resource use are selected. Typical works of this phase:

 performance of basic design work;

 development of private technical specifications;

 implementation of conceptual design;

 preparation of technical specifications and instructions;

 presentation of design development, examination and approval.

Development of

At this phase, coordination and operational control of project work is carried out, subsystems are manufactured, combined and tested. Main content:

 execution of works on software development;

 preparation for implementation of the system;

 control and regulation of the main indicators of the project.

Commissioning the system

During this phase, tests are carried out, trial operation of the system in real conditions,

negotiations are under way on the results of the project and on possible new contracts. Main types of work:

 complex tests;

The concept of the life cycle is one of the basic concepts of the information systems design methodology. The life cycle of an information system is a continuous process that starts from the moment a decision is made to create an information system and ends when it is completely removed from service.

There is an international standard that regulates the life cycle of information systems - ISO / IEC 12207.

ISO stands for International Organization of Standardization. IEC- International Electrotechnical Commission

The ISO / IEC 12207 standard defines a life cycle framework containing the processes, activities and tasks that must be performed during the creation of an information system.

According to this standard, the life cycle structure is based on three groups of processes:

 main life cycle processes (acquisition, delivery, development, operation, maintenance);

Ancillary processes that support the main processes (documentation, configuration management, quality assurance, verification, validation, assessment, audit, problem resolution);

Organizational processes (project management, creation of project infrastructure, definition, assessment and improvement of the life cycle itself, training).

The methodology for creating information systems consists in organizing the process of building an information system and providing control over this process in order to ensure that the requirements for both the system itself and the characteristics of the development process are met.

The main tasks, the solution of which should be provided by methodology for creating corporate information systems(using the appropriate toolbox) are as follows:

 ensuring the creation of information systems that meet the goals and objectives of the enterprise and meet the requirements imposed on them for the automation of business processes;

 guarantee of the creation of a system with the specified parameters within a specified time within a predetermined budget;

 simplicity of maintenance, modification and expansion of the system in order to ensure its compliance with the changing conditions of the enterprise;

 ensuring the creation of corporate information systems that meet the requirements of openness, portability and scalability;

 the possibility of using information technology tools (software, databases, computer technology, telecommunications) developed earlier and used at the enterprise in the system being created.

Methodologies, technologies and design tools (CASE-tools) form the basis of the design of any information system. The methodology is implemented through specific technologies and their supporting standards, methodologies and tools that ensure the implementation of the life cycle processes of information systems.

Design technology can be represented as a combination of three components:

 a given sequence of technological design operations;

 criteria and rules used to assess the results of technological operations;

 graphic and textual means (notations) used to describe the designed system.

Each technological operation must be provided with the following material and information resources:

 data obtained during the previous operation (or initial data) presented in standard form;

 methodological materials, instructions, regulations and standards;

 software and hardware;

 performers.

The results of the operation should be presented in some standard form that ensures their adequate perception during the next technological operation (in which they will be used as initial data).

The following series can be formulated general requirements which must be satisfied technology of design, development and maintenance of information systems:

 maintain the full life cycle of the information system;

 to ensure the guaranteed achievement of the goals of the system development with the specified quality and within the specified time;

 provide the possibility of dividing large projects into a number of subsystems - decomposition of the project into its component parts, developed by groups of performers of a limited number, with the subsequent integration of the component parts;

 The technology should provide the ability to conduct work on the design of individual subsystems in small groups (3-7 people). This is due to the principles of team manageability and productivity improvement by minimizing the number of external relations;

 to ensure the minimum time for obtaining a workable system;

Decomposition of the project allows you to increase the efficiency of work. The subsystems into which the project is divided should be loosely coupled in terms of data and functions. Each subsystem is developed by a separate development team. At the same time, it is necessary to ensure the coordination of work and eliminate duplication of results obtained by each the project team... This does not mean the implementation of the information system as a whole, but the development of its individual subsystems. As a rule, even in the presence of a fully completed project, the implementation of the developed system is carried out sequentially, in separate subsystems. Implementation of the entire system in a short time may require the involvement of a large number of developers, while the effect may be lower than when implementing individual subsystems in a shorter time frame by a smaller number of developers.

Provide the ability to manage the configuration of the project, maintain versions of the project and its components, the possibility of automatic release project documentation and synchronization of its versions with project versions;

 ensure the independence of the executed design solutions from the system implementation means - the database management system, operating system, language and programming system.

Creation, maintenance and development of modern complex information systems is based on the methodology of building such systems as open. Open information systems are created in the process of informatization of all the main spheres of modern society: government bodies, financial and credit sphere, information services for entrepreneurship, production sphere, science, education. The development and use of open information systems is inextricably linked with the application of standards based on the methodology of functional standardization of information technology.

Information system profile concept

When creating and developing complex, distributed, replicable information systems, flexible formation and application of harmonized sets of basic standards and regulatory documents of different levels is required, the allocation of requirements and recommendations necessary for the implementation of the specified system functions. For unification and regulation, such sets of basic standards must be adapted and specified in relation to certain classes of projects, functions, processes and system components. In this regard, the concept of an information system profile as the main tool for functional standardization was singled out and formed.

Profile is a collection of several (or a subset of one) basic standards with clearly defined and harmonized subsets of mandatory and optional capabilities, designed to implement a given function or group of functions.

The profile is formed based on the functional characteristics of the standardization object. In the profile, the permissible capabilities and values ​​of the parameters of each base standard and / or normative document included in the profile are highlighted and set.

The profile should not contradict the basic standards and normative documents used in it. It must use the optional features selected from the alternatives and the parameter values ​​within the allowed limits.

On the basis of one set of basic standards, different profiles can be formed and approved for different projects of information systems. The limitations of the basic documents of the profile and their consistency, carried out by the developers of the profile, must ensure the quality, compatibility and correct interaction of the individual components of the system corresponding to the profile in the given area of ​​its application.

Basic standards and profiles, depending on the problem-oriented area of ​​application of information systems, can be used as direct directive, guidance or recommendation documents, as well as a regulatory framework necessary for the selection or development of automation tools for technological stages or processes of creation, maintenance and development of information systems.

Usually considered two groups of profiles:

 regulating the architecture and structure of the information system;

 regulating processes of design, development, application, maintenance and development of the system.

Depending on the area of ​​application, profiles can have different categories and, accordingly, different approval statuses:

 profiles of a specific information system, defining standardized design solutions within of this project;

 information system profiles intended for solving a certain class of applied problems.

Profiles of information systems unify and regulate only a part of the requirements, characteristics, quality indicators of objects and processes, distinguished and formalized on the basis of standards and regulatory documents. Another part of the functional and technical characteristics of the system is determined by customers and developers creatively, without taking into account the provisions of regulatory documents.

Principles of forming an information system profile

The use of information systems profiles is designed to solve the following tasks:

 reducing the complexity of projects;

 improving the quality of the components of the information system;

 ensuring the extensibility and scalability of the systems being developed;

 ensuring the possibility of functional integration into the information system of tasks that were previously solved separately;

 ensuring the portability of the application software.

Depending on which of these tasks are of the highest priority, the choice of standards and documents for the formation of the profile is made.

The relevance of using information system profiles is due to modern the state of standardization of information technology, which is characterized by the following features:

 there are many international and national standards that are not

fully and unevenly meet the needs for standardization of objects and processes of creation and use of complex information systems;

 long terms of development, coordination and approval of international and national standards lead to their conservatism and chronic lag behind modern information technologies;

 functional standards support and regulate only the simplest objects and routine, massive processes: telecommunications, programming, documenting programs and data. The most complex and creative processes of creation and development of large distributed information systems - system analysis and design, integration of components and systems, testing and certification - are almost not supported by the requirements and recommendations of standards due to the difficulty of their formalization and unification;

 improvement and harmonization of normative and methodological documents in a number of cases make it possible to create national and international standards on their basis.

The approaches to the formation of profiles of information systems can be different. In the international functional standardization of information technologies, a rather rigid concept of a profile has been adopted. It is believed that only international and national approved standards can be its basis. The use of de facto standards and company regulations is not allowed. With this approach, it is difficult to unify, regulate and parameterize a set of specific functions and characteristics of complex objects of architecture and structure of modern information systems. Another approach to the development and application of information system profiles is to use a set of adapted and parameterized basic international and national standards and open specifications that meet de facto standards and recommendations of international consortia.

The Open Systems Environment Reference Model (OSE / RM) defines the division of any information system into two components: applications (application programs and software systems) and the environment in which these applications operate.

Standardized Application Program Interfaces (APIs) are defined between applications and the environment and are a necessary part of the profiles of any open system.

In addition, the profiles can define unified interfaces for interaction of functional parts with each other and interfaces for interaction between components of the system environment. The specifications of the functions performed and the interaction interfaces can be executed in the form of profiles of the system components.

Thus, information system profiles with a hierarchical structure may include:

 standardized descriptions of the functions performed by this system;

 functions of interaction of the system with the external environment for it;

 standardized interfaces between applications and the information system environment;

 profiles of individual functional components included in the system. To effectively use a specific profile, you must:

 highlight the problem-oriented areas of functioning united by a logical connection, where standards common for one organization or a group of organizations can be applied;

 identify standards and regulations, their use cases and parameters that need to be included in the profile;

 document areas of a specific profile where the creation of new standards or regulations is required, and identify characteristics that may be important for the development of missing standards and regulations for this profile;

 formalize the profile in accordance with its category, including standards, various versions of regulatory documents and additional parameters that are directly related to the profile;

When using profiles, it is important to ensure that they are validated through testing, testing and certification. This requires the creation of a control and testing technology in the process of applying the profile. This technology should be supported by a set of techniques, tools, the composition and content of the documents to be drawn up at each stage of the project.

The use of profiles promotes unification in the development of tests that check the quality and interaction of the components of the designed information system. Profiles should be defined in such a way that testing of their implementation can be carried out as fully as possible according to a standardized methodology. In this case, it is possible to use previously developed methods, since international standards and profiles are the basis for the creation of generally recognized certification tests.

The structure of information systems profiles

The development and application of profiles is an organic part of the design, development and maintenance of information systems. Profiles characterize each specific information system at all stages of its life cycle, setting an agreed set of basic standards that the system and its components must comply with. Standards that are important from the point of view of the customer should be set in the technical specification for the design of the system and make up its primary profile. What is not specified in the TK initially remains at the discretion of the system developer, who, guided by the requirements of the TK, can supplement and develop the system profiles and subsequently coordinate them with the customer. Thus, the profile of a specific system is not static, it develops and is concretized in the process of designing an information system and is drawn up as part of the system design documentation.

The profile of a specific system includes the specifications of the components developed as part of this project, and the specifications of the ready-made software and hardware used, if these tools are not specified by the relevant standards. After the design and testing of the system is completed, during which its compliance with the profile is checked, the profile is used as the main tool for supporting the system during operation, modernization and development.

Introduction

Conclusion

Literature

Introduction

The development of various spheres of human activity on the present stage impossible without widespread use computing technology and creation of information systems different directions... Information processing in such systems has become an independent scientific and technical direction.

After the stage of building the information model, the design of the system begins. At this stage, the choice of technological solutions is made, on the basis of which the information system will be built.

Information in modern world has become one of the most important resources, and information systems (IS) have become necessary tool in almost all areas of activity.

In real conditions, design is a search for a method that meets the requirements of the functionality of the system by means of available technologies, taking into account the given constraints.

The variety of tasks solved with the help of IS has led to the emergence of many different types of systems that differ in the principles of construction and the rules for information processing inherent in them.

The purpose test work is - to consider step by step, the process of creating information systems.

The tasks of this work are to find out the main goal of design, as well as the goal of creating information systems.

1. Design of information systems

Designing information systems always starts with defining the goal of the project. The main task of any successful project is that at the time of the system start-up and during the entire period of its operation it would be possible to ensure:

· The required functionality of the system and the degree of adaptation to the changing conditions of its functioning;

The required throughput systems;

· The required response time of the system to the request;

· Trouble-free operation of the system in the required mode, in other words - the readiness and availability of the system to process user requests;

· Ease of operation and support of the system;

· Necessary security.

Performance is the main determinant of system efficiency. Good design is the foundation of a high performance system.

Information systems design covers three main areas:

· Design of data objects that will be implemented in the database;

· Designing programs, screens, reports that will ensure the execution of queries to data;

· Taking into account a specific environment or technology, namely: network topology, hardware configuration, architecture used (file-server or client-server), parallel processing, distributed data processing, etc.

According to modern methodology, the process of creating an IS is a process of building and sequential transformation of a number of agreed models at all stages of the IS life cycle (LC). At each stage of the life cycle, specific models are created - organizations, IS requirements, IS project, application requirements, etc. Models are formed by working groups of the project team, saved and accumulated in the project repository. The creation of models, their control, transformation and provision for collective use is carried out using special software tools - CASE-tools.

The process of creating an IS is divided into a number of stages (stages), limited by some time frame and ending with the release of a specific product (models, software products, documentation, etc.).

Usually, the following stages of creating an IS are distinguished: the formation of requirements for the system, design, implementation, testing, commissioning, operation and maintenance.

The initial stage of the process of creating an IS is the modeling of business processes occurring in the organization and realizing its goals and objectives. The organization model, described in terms of business processes and business functions, allows you to formulate the basic requirements for IS. This fundamental premise of the methodology ensures objectivity in the formulation of system design requirements. The set of models for describing the IP requirements is then transformed into a system of models describing the conceptual design of the IP. Models of IS architecture, requirements for software (software) and information support (IO) are formed. Then the architecture of software and IO is formed, corporate databases and individual applications are allocated, models of requirements for applications are formed and their development, testing and integration are carried out.

The purpose initial stages creation of IS, performed at the stage of analysis of the organization's activities, is the formation of requirements for IS that correctly and accurately reflect the goals and objectives of the customer organization. In order to specify the process of creating an IP that meets the needs of the organization, it is necessary to find out and clearly articulate what these needs are. To do this, it is necessary to define the requirements of customers for the IP and map them in the language of models into the requirements for the development of the IP project so as to ensure compliance with the goals and objectives of the organization.

The task of forming IS requirements is one of the most responsible, difficult to formalize and the most expensive and difficult to correct in case of an error. Modern tools and software products allow you to quickly create IS based on ready-made requirements... But often these systems do not satisfy customers, require numerous modifications, which leads to a sharp rise in the cost of the actual cost of the IP. The main reason for this situation is incorrect, inaccurate or incomplete definition of IP requirements at the analysis stage.

At the design stage, data models are first and foremost formed. Designers receive analysis results as input. Building logical and physical data models is an essential part of database design. The information model obtained during the analysis is first transformed into a logical and then into a physical data model.

In parallel with the design of the database schema, process design is performed to obtain specifications (descriptions) of all IS modules. Both of these design processes are closely related because some of the business logic is usually implemented in the database (constraints, triggers, stored procedures). The main goal of process design is to map the functions obtained at the analysis stage into the modules of the information system. When designing modules, program interfaces are determined: menu layout, window views, hotkeys and associated calls.

The end products of the design phase are:

· Database schema (based on the ER-model developed at the analysis stage);

· A set of specifications for system modules (they are built on the basis of function models).

In addition, at the design stage, the development of the IS architecture is also carried out, including the choice of a platform (platforms) and an operating system (operating systems). In a heterogeneous IC, several computers can run on different hardware platforms and running different operating systems. In addition to choosing a platform, the following characteristics of the architecture are determined at the design stage:

· Whether it will be a "file-server" or "client-server" architecture;

Whether it will be a 3-tier architecture with the following layers: server, middleware (application server), client software;

· Whether the database will be centralized or distributed. If the database is going to be distributed, what mechanisms will be used to maintain the consistency and relevance of the data;

· Whether the database will be homogeneous, that is, whether all database servers will be from the same vendor (for example, all servers are Oracle only, or all servers are only DB2 UDB). If the database is not homogeneous, what software will be used to exchange data between DBMS of different manufacturers (existing or developed specifically as part of the project);

· Whether parallel database servers (eg Oracle Parallel Server, DB2 UDB) will be used to achieve the desired performance.

The design phase ends with the development of a technical design for the IS. At the stage of implementation, the creation of software for operational documentation is carried out.

After completing the development of a separate module of the system, an autonomous test is performed, which has two main goals:

· Detection of module failures (hard failures);

· Compliance of the module with the specification (availability of all necessary functions, absence of unnecessary functions).

After the autonomous test is successful, the module is included in the developed part of the system, and a group of generated modules undergoes communication tests, which should track their mutual influence.

Further, a group of modules is tested for reliability of operation, that is, they pass, firstly, tests to simulate system failures, and secondly, tests of operating time between failures. The first group of tests shows how well the system recovers from software failures, hardware failures. The second group of tests determines the degree of stability of the system during normal operation and allows you to estimate the uptime of the system. The stability test suite should include tests that simulate the peak load on the system.

Then the entire set of modules undergoes a system test - an internal acceptance test of the product, showing the level of its quality. This includes functionality tests and system reliability tests.

The last test of the information system is acceptance tests. Such a test involves showing the information system to the customer and should contain a group of tests that simulate real business processes to show that the implementation meets the customer's requirements.

 

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