The life cycle of an information system. Stages of the life cycle of a technical system

in electrical engineering). This standard defines the structure of the life cycle, containing the processes, activities and tasks that must be performed during the creation of the PS.

In this PS standard (or software) is defined as a set of computer programs, procedures, and possibly associated documentation and data. The process is defined as a set of interrelated actions that transform some input data into output data (G. Myers calls this data translation). Each process is characterized by certain tasks and methods for their solution. In turn, each process is divided into a set of actions, and each action is divided into a set of tasks. Each process, action, or task is initiated and executed by another process as needed, and there are no predetermined execution sequences (of course, while maintaining the input data connections).

It should be noted that in the Soviet Union, and then in Russia, the creation of software (software) initially, in the 70s of the last century, was regulated by the GOST ESPD standards (Unified System for Program Documentation - GOST 19.XXX series), which were focused on the class relatively simple programs small volume created by individual programmers. At present, these standards are outdated conceptually and in form, their validity has expired and their use is inappropriate.

The processes of creating automated systems (AS), which also include software, are regulated by GOST 34.601-90 standards " Information technology. Set of standards for automated systems. Stages of creation", GOST 34.602-89 "Information technology. Set of standards for automated systems. Technical task for the creation of an automated system" and GOST 34.603-92 "Information technology. Types of tests of automated systems". However, many provisions of these standards are outdated, while others are not reflected enough to be used for serious projects for the creation of PS. Therefore, it is advisable to use modern international standards in domestic developments.

In accordance with the ISO / IEC 12207 standard, all software life cycle processes are divided into three groups (Fig. 5.1).

Rice. 5.1.

Five main processes are defined in the groups: acquisition, supply, development, operation and maintenance. Eight sub-processes ensure the execution of the main processes, namely documentation, configuration management, quality assurance, verification, validation, joint assessment, audit, problem resolution. The four organizational processes provide governance, infrastructure building, improvement and learning.

5.2. The main processes of the life cycle of the PS

The acquisition process consists of the activities and tasks of the customer purchasing the software. This process covers the following activities:

1. acquisition initiation;
2. preparation of application proposals;
3. preparation and adjustment of the contract;
4. supervision of the activities of the supplier;
5. acceptance and completion of work.

Acquisition initiation includes the following tasks:

1. determination by the customer of his needs in the acquisition, development or improvement of the system, software products or services;
2. making a decision regarding the acquisition, development or improvement of existing software;
3. checking the availability of the necessary documentation, warranties, certificates, licenses and support in case of purchasing a software product;
4. preparation and approval of the acquisition plan, including system requirements, type of contract, responsibilities of the parties, etc.

Bids must contain:

1. system requirements;
2. list of software products;
3. terms of acquisition and agreement;
4. technical limitations (for example, on the operating environment of the system).

Bids are sent to a selected supplier or multiple suppliers in the event of a tender. A supplier is an organization that enters into a contract with a customer for the supply of a system, software or software service on the terms specified in the contract.

Preparation and adjustment of the contract includes the following tasks:

1. determination by the customer of the procedure for selecting a supplier, including criteria for evaluating the proposals of possible suppliers;
2. selection of a specific supplier based on the analysis of proposals;
3. preparation and conclusion supplier contracts;
4. making changes (if necessary) to the contract in the process of its implementation.

Supplier performance is supervised in accordance with the actions provided for in the joint assessment and audit processes. During the acceptance process, the necessary tests are prepared and performed. Completion of work under the contract is carried out in case of satisfaction of all conditions of acceptance.

The delivery process covers the activities and tasks performed by a vendor that supplies a customer with a software product or service. This process includes the following steps:

1. delivery initiation;
2. preparing a response to bids;
3. preparation of the contract;
4. contract work planning;
5. performance and control of contractual works and their evaluation;
6. delivery and completion of works.

The initiation of the supply consists in the consideration by the supplier of the bids and the decision whether to agree with the requirements and conditions set out or to offer their own (agreed). Planning includes the following tasks:

1. making a decision by the supplier regarding the performance of work on its own or with the involvement of a subcontractor;
2. development by the supplier of a project management plan containing the organizational structure of the project, delimitation of responsibilities, technical requirements to the development environment and resources, management of subcontractors, etc.

The development process provides for the activities and tasks performed by the developer, and covers the work of creating software and its components in accordance with specified requirements. This includes the preparation of design and operational documentation, the preparation of materials necessary for performance testing, and quality of software products, materials necessary for organizing staff training, etc.

The development process includes the following steps:

1. preparatory work;
2. analysis of the requirements for the system;
3. system architecture design;
4. analysis of requirements for software;
5. software architecture design;
6. detailed software design;
7. software coding and testing;
8. software integration;
9. software qualification testing;
10. system integration;
11. qualification testing of the system;
12. software installation;
13. software acceptance.

The preparatory work begins with the selection of a software life cycle model appropriate to the scale, significance, and complexity of the project. The activities and tasks of the development process should be consistent with the chosen model. The developer must select, adapt to the conditions of the project and use the standards, methods and methods agreed with the customer. development tools, as well as draw up a work plan.

Analysis of the requirements for the system involves the definition of its functionality, custom requirements, requirements for reliability, security, requirements for external interfaces, performance, etc. System requirements are evaluated based on feasibility criteria and verifiability during testing.

System architecture design consists in determining the components of its equipment (hardware), software and operations performed by the personnel operating the system. The architecture of the system must comply with the system requirements and accepted design standards and practices.

Software requirements analysis involves determining the following characteristics for each software component:

1. functionality, including performance characteristics and operating environment of the component;
2. external interfaces;
3. reliability and safety specifications;
4. ergonomic requirements;
5. requirements for the data used;
6. installation and acceptance requirements;
7. requirements for user documentation;
8. requirements for operation and maintenance.

The software requirements are evaluated based on the criteria of compliance with the requirements for the system as a whole, feasibility and verifiability during testing.

Software architecture design includes the following tasks for each software component:

1. transformation of software requirements into an architecture that defines high level software structure and composition of its components;
2. development and documentation of program interfaces for software and databases (DB);
3. development of a preliminary version of user documentation;
4. development and documentation of prerequisites for tests and software integration plan.

Detailed software design includes the following tasks:

1. description of software components and interfaces between them at a lower level, sufficient for subsequent coding and testing;
2. developing and documenting a detailed database design;
3. updating (if necessary) user documentation;
4. development and documentation of test requirements and a plan for testing software components;

Software coding and testing includes the following tasks:

1. coding and documenting each component of the software and database, as well as preparing a set of test procedures and data for testing them;
2. testing each component of the software and database for compliance with the requirements for them, followed by documentation of the test results;
3. updating documentation (if necessary);
4. updating the software integration plan.

Software integration provides for the assembly of the developed software components in accordance with the integration and testing plan for the aggregated components. For each of the aggregated components, test suites and test procedures are developed to test each of the competencies in subsequent proficiency testing. A qualification requirement is a set of criteria or conditions that must be met in order to qualify. software as conforming to its specifications and ready for use in the field.

Qualification testing of software is carried out by the developer in the presence of the customer (

The operation process covers the activities and tasks of the organization of the operator operating the system. The operation process includes the following steps.

1. Preparatory work, which includes carrying out the following tasks by the operator:

   1. planning activities and work performed during operation, and setting operational standards;
   2. determination of procedures for localization and resolution of problems arising during operation.
2. Operational testing carried out for each next edition of the software product, after which this edition is transferred to operation.
3. The actual operation of the system, which is performed in the environment intended for this in accordance with the user documentation.
4. analysis of problems and requests for software modification (analysis of messages about a problem that has arisen or a request for modification, assessment of the scale, cost of modification, resulting effect, assessment of the feasibility of modification);
5. software modification (making changes to software product components and documentation in accordance with the rules of the development process);
6. verification and acceptance (in terms of the integrity of the system being modified);
7. transfer of software to another environment (conversion of programs and data, parallel operation of software in the old and new environment for a certain period of time);
8. decommissioning of the software by the decision of the customer with the participation of the operating organization, maintenance service and users. At the same time, software products and documentation are subject to archiving in accordance with the contract.

The life cycle is not a time period of existence, but a process of successive changes in state, due to the type of impacts produced (R 50-605-80-93).

The term "system life cycle" is usually understood as the evolution new system in the form of several stages, including such important stages as concept, development, production, operation and final decommissioning. :70

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Video 22. Software life cycle. Stages of software development. classic model software development

"Life cycle of a system or project" - training No. 2.

Product Life Cycle.mp4

Defect lifecycle

Organization life cycle

Subtitles

History of the concept

The concept of the life cycle emerged at the end of the 19th century. as a set of ideas that include the ideas of heredity and development at the level of individuals and organisms, as well as adaptation, survival and extinction at the level of individual species and entire populations of living organisms.

Generic System Life Cycle Models

There is no single life cycle model that satisfies the requirements of every possible task. Various standards organizations, government agencies, and engineering communities publish their own models and technologies that can be used to construct the model. Thus, it is inappropriate to assert the existence of any one possible algorithm for building a model. Nevertheless, any life cycle model can be divided into a series of basic steps that will reflect individual important stages.

Some systems engineers suggest considering a system life cycle model based on the following three sources: the U.S. Department of Defense (DoD) Logistics Management Model (DoD 5000.2), the ISO/IEC 15288 model, and the National Society of Professional Engineers (NSPE) model. ). :71

ISO/IEC 15288 Generic Life Cycle Model

According to the standard, the processes and activities of the life cycle are defined, appropriately configured and used during the life cycle stage, in order to fully satisfy the goals and results at this stage. may be involved in various stages of the life cycle. different organizations. There is no single universal model of systems life cycles. Certain stages of the life cycle may be absent or present depending on each specific case of system development. :34

The following life cycle stages were given as an example in the standard:

1. Design stage.
2. Development stage.
3. Production stage.
4. Application stage.
5. Application support stage.
6. Stage of termination of use and write-off.

The 2008 version of the standard (ISO/IEC 15288:2008) does not include examples of life cycle stages.

US Department of Defense Generic Life Cycle Model

To manage the risks in the application of advanced technologies, and to minimize costly technical or managerial errors, the US Department of Defense has developed a guide containing all necessary principles systems development. These principles are included in a special list of directives - DoD 5000.

The DoD Logistics Management System Life Cycle Model consists of five stages:71:

• analysis;
• technology development;
• engineering and production development;
• production and deployment;
• operation and support.

National Society of Professional Engineers (NSPE) System Life Cycle Reference Model

This model is adapted for the development of commercial systems. This model is mainly focused on the development of new products, usually the result of technical progress. The NSPE model is alternative view on the US DoD version model. The life cycle according to the NSPE model is divided into six stages:72:

• concept;
• technical implementation;
• development;
• commercial validation and pre-production;
• full-scale production;
• end product support.

Product life cycle model according to R 50-605-80-93

In the guiding document R 50-605-80-93, the life cycle of an industrial product, including military equipment, is carefully worked out.

For civil industrial products, the following stages are proposed:

• research and design;
• manufacturing;
• circulation and implementation;
• exploitation or consumption.

As part of the life cycle of civil industrial products, it is proposed to consider 73 types of work and 23 types of stakeholders (“work participants” in the terminology of the document).

For military industrial products, the following stages are proposed:

• research and development justification;
• development;
• production;
• exploitation;
• overhaul.

As part of the life cycle of military industrial products, it is proposed to consider 25 types of work and 7 types of stakeholders (participants in the work).

Generic Software Life Cycle Model

The stages of the system life cycle and their component phases, presented in the Figure “System Life Cycle Model”, refer to the majority of complex systems, including those containing software with a significant amount of functionality at the component level. In software-intensive systems, in which the software performs almost all functions (as in modern financial systems, in air ticket booking systems, on the global Internet, etc.), as a rule, life cycles are similar in content, but are often complicated by iterative processes and prototyping. :72-73

Main stages of the system life cycle (Kossiakoff, Sweet, Seymour, Biemer)

As shown in the System Life Cycle Model figure, the System Life Cycle Model contains 3 stages. The first 2 stages are development, and the third stage covers post-development. These stages show the more general transitions from state to state, in the life cycle of a system, and also show changes in the type and scope of activities involved in systems engineering. The stages are :73:

• concept development stage;
• stage of technical development;
• post-development stage.

Concept development stage

The purpose of the concept development stage is to evaluate new opportunities in the field of application of the system, develop preliminary system requirements and possible design solutions. The conceptual design development stage begins with the realization of the need to create a new system or modify an existing one. The stage includes the beginning of the research of the facts, the planning period, the economic, technical, strategic and market bases for future actions are assessed. There is a dialogue between stakeholders and developers. :

Main objectives of the concept development stage: :74

1. Conduct studies to establish what is necessary for a new system, as well as to establish the technical and economic feasibility of this system.
2. Explore potential system concepts and formulate and validate a set of system performance requirements.
3. Select the most attractive system concept, determine its functional characteristics, and develop a detailed plan for the subsequent stages of design, production and operational deployment of the system.
4. Develop any new technology suitable for the chosen system concept and validate its ability to meet the needs.

Stage of technical development

The engineering development stage refers to the process of designing a system to implement the functions formulated in the system concept into a physical implementation that can be supported and successfully operated in its operating environment. Systems engineering is primarily concerned with the direction of development and design, interface management, development of test plans, and determines how discrepancies in system performance not verified during testing and evaluation should be appropriately corrected. The bulk of engineering activities are carried out at this stage.

The main objectives of the technical development stage are:74:

1. Perform engineering development of a system prototype that meets performance, reliability, maintainability, and safety requirements.
2. Design a system usable and demonstrate its operational suitability.

Post-development stage

The post-development stage consists of activities outside of the system development period, but still requires significant support from the system engineers, especially when unforeseen problems are encountered that need to be resolved as soon as possible. In addition, advances in technology often require internal service system upgrades, which can be as dependent on systems engineering as the concept and engineering stages.

The post-development stage of a new system begins after a successful operation of testing and evaluating this system (acceptance testing), release to production and subsequent operational use. Until major development is completed, systems engineering will continue to play a major supporting role.

ISO/IEC 15288:2008 Systems and software engineering — Life cycle processes

Kossiakoff A., Sweet W. N., Seymour S. J., Biemer S. M. Systems Engineering Principles and Practices. - 2nd ed. - Hoboken, New Jersey: A John Wiley & Sons, 2011. - 599 p. - ISBN 978-0-470-40548-2.

Batovrin V. K. , Bakhturin D.A. Life cycle management of technical systems. - 2012.

GOST R ISO/IEC 15288-2005 Information technology. System engineering. Systems Life Cycle Processes

R 50-605-80-93. Recommendations. System for the development and production of products. Terms and definitions (Link to text).

The concept of the life cycle is one of basic concepts design methodology information systems. The life cycle of an information system is a continuous process starting! from the moment the decision to create an information system is made and ends at the moment of its complete withdrawal from operation.

The ISO/IEC 12207 standard defines a life cycle framework that contains 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:

1. the main processes of the life cycle (acquisition, supply, development, operation, maintenance);

2. auxiliary processes that ensure the implementation of the main processes (documentation, configuration management, quality assurance, verification, attestation, assessment, audit, problem resolution);

3. organizational processes (project management, creation of project infrastructure, definition, evaluation and improvement of the life cycle itself, training).

Among the main life cycle processes, development, operation and maintenance are of the greatest importance. Each process is characterized by certain tasks and methods for their solution, initial data; obtained at the previous stage, and the results.

1. Development

The development of an information system includes all work on the development of information software and its components in accordance with the specified requirements. Information software development also includes:

1. registration of design and operational documentation;

2. preparation of materials necessary for testing covert software products;

3. development of materials necessary for the organization of staff training.

Development is one of the most important processes of the life cycle of an information system and, as a rule, includes strategic planning, analysis, design and implementation (programming).

2. Operation

Operational work can be divided into preparatory and main. The preparations include:

1. configuring the database and user workstations;

2. providing users with operational documentation;

3. staff training.

Main maintenance work include;

1. Direct operation;

2. localization of problems and elimination of their causes;

3. software modification;

4. preparation of proposals for improving the system;

5. development and modernization of the system.

3. Escort

Services technical support play a very prominent role in the life of any corporate information system. Availability of qualified Maintenance at the stage of operation of the information system is necessary condition to solve the tasks assigned to it. Moreover, errors of maintenance personnel can lead to obvious or hidden financial losses comparable to the cost of the information system itself.

Life cycle models

The life cycle model is understood as a structure that determines the sequence of execution and the relationship of processes, activities and tasks performed throughout the life cycle. The life cycle model depends on the specifics of the information system and the specifics of the conditions in which the latter is created and operates.

To date, the most widely used are the following main life cycle models:

1. task model;

2. cascade model (or systemic) (70-85);

3. spiral model (present).

Task model

When developing a system "bottom-up" from individual tasks to the entire system (task model), a single approach to development is inevitably lost, problems arise in the informational docking of individual components. As a rule, as the number of tasks increases, the difficulties increase, you have to constantly change already existing programs and data structures. The rate of development of the system slows down, which slows down the development of the organization itself. However, in some cases, this technology may be appropriate:

Extreme urgency (it is necessary that at least somehow the tasks are solved; then you have to do everything again);

Experiment and adaptation of the customer (algorithms are not clear, solutions are groped by trial and error).

The general conclusion is that it is impossible to create a sufficiently large effective information system in this way.

Cascade model

In the early, not very large homogeneous information systems, each application was a single whole. To develop this type of application, a cascading method was used. Its main characteristic is the division of the entire development into stages, and the transition from one stage to the next occurs only after the work on the current one is fully completed (Fig. 2). Each stage culminates in the release of a complete set of documentation, sufficient for development to be continued by another development team.

The positive aspects of applying the cascade approach are as follows:

at each stage, a complete set is formed project documentation, which meets the criteria for completeness and consistency;

the stages of work performed in a logical sequence allow you to plan the timing of the completion of all work and the corresponding costs.

Rice. . Waterfall development scheme

The waterfall approach has proven itself in building information systems for which, at the very beginning of development, all requirements can be formulated quite accurately and completely in order to give developers the freedom to implement them as best as possible from a technical point of view. This category includes complex settlement systems, real-time systems and other similar tasks. However, in the process of using this approach, a number of its shortcomings were discovered, primarily due to the fact that the real process of creating systems never completely fit into such a rigid scheme. In the process of creation, there was a constant need to return to previous stages and clarify or revise earlier decisions taken. As a result, the actual process of creating software took next view(Fig. 3):

Rice. 3. The real process of software development according to the cascade scheme

The main disadvantage of the cascade approach is a significant delay in obtaining results. Coordination of the results with users is carried out only at the points planned after the completion of each stage of work, the requirements for information systems are "frozen" in the form of a technical task for the entire time of its creation. Thus, users can submit their comments only after the work on the system is fully completed. If requirements are not accurately stated or changed over a long period of software development, users end up with a system that does not meet their needs. Models (both functional and informational) of an automated object may become obsolete simultaneously with their approval. Essence systems approach to the development of an IS is its decomposition (partitioning) into automated functions: the system is divided into functional subsystems, which in turn are divided into subfunctions, subdivided into tasks, and so on. The partitioning process continues up to specific procedures. At the same time, the automated system retains a holistic view in which all components are interconnected. Thus, this model has the main advantage of systematic development, and the main disadvantages are slow and expensive.

spiral model

To overcome these problems, a spiral life cycle model was proposed (Fig. 4), which focuses on the initial stages of the life cycle: analysis and design. At these stages, the feasibility of technical solutions is tested by creating prototypes. Each turn of the spiral corresponds to the creation of a piece or version of the software, on which the goals and characteristics of the project are specified, its quality is determined, and the work of the next turn of the spiral is planned. Thus, the details of the project are deepened and consistently concretized, and as a result, a reasonable option is selected, which is brought to implementation.

Development by iterations reflects the objectively existing spiral cycle of system creation. Incomplete completion of work at each stage allows you to move on to the next stage without waiting for the complete completion of work on the current one. With iterative development, the missing work can be completed in the next iteration. The main task is to show users of the system a workable product as soon as possible, thereby activating the process of clarifying and supplementing requirements.

The main problem of the spiral cycle is determining the moment of transition to the next stage. To solve it, it is necessary to introduce time limits for each of the stages of the life cycle. The transition proceeds according to plan, even if not all planned work is completed. The plan is drawn up on the basis of statistical data obtained in previous projects, and personal experience developers.

Figure 4. Spiral model of the life cycle of IS

One of the possible approaches to software development in the framework of the spiral life cycle model is recent times widespread methodology for rapid application development RAD (Rapid Application Development). This term is usually understood as a software development process containing 3 elements:

a small team of programmers (from 2 to 10 people);

short, but carefully worked out production schedule (from 2 to 6 months);

an iterative cycle in which developers, as the application begins to take shape, request and implement in the product the requirements received through interaction with the customer.

The software life cycle according to the RAD methodology consists of four phases:

1. phase of requirements definition and analysis;

2. design phase;

3. implementation phase;

4. implementation phase.

Lecture 6. Classification of information systems

Information system- an interconnected set of means, methods and personnel used to store, process and issue information in the interests of achieving the goal

Scale classification

By scale, information systems are divided into the following groups:

1. single;

2. group;

3. corporate.

Single information systems are implemented, as a rule, on a stand-alone personal computer (the network is not used). Such a system may contain several simple applications connected by a common information fund, and is designed for the operation of one user or a group of users who share the same time. workplace. Similar applications can be created using the so-called desktop or local systems database management (DBMS). Among the local DBMS, the most famous are Clarion, Clipper, FoxPro, Paradox, dBase and Microsoft Access.

Group information systems are focused on the collective use of information by members of the working group and are most often built on the basis of a local area network. These applications are developed using database servers (also called SQL servers) for workgroups. There is quite a large number of various SQL servers, both commercial and free. Among them, the most famous database servers are Oracle, DB2, Microsoft SQL Server, InterBase, Sybase, Informix.

Corporate information systems are an evolution of systems for workgroups, they are focused on large companies and can support geographically dispersed nodes or networks. Basically, they have a hierarchical structure of several levels. Such systems are characterized by a client-server architecture with specialization of servers or a multi-level architecture. When developing such systems, the same database servers can be used as when developing group information systems. However, in large information systems, the most widely used servers are Oracle, DB2 and Microsoft SQL Server.

For group and corporate systems, the requirements for the reliability of operation and data safety are significantly increased. These properties are provided by maintaining the integrity of data, links and transactions in the database servers.

Classification by scope

According to the scope of information systems are usually divided into four groups:

1. transaction processing systems;

2. decision-making systems;

3. information and reference systems;

4. office information systems.

Transaction processing systems, in turn, according to the efficiency of data processing, are divided into batch information systems and operational information systems. In information systems organizational departments the mode of online transaction processing prevails, to reflect up-to-date state of the subject area at any time, and batch processing occupies a very limited part.

Decision support systems - DSS (Decision Support Systeq) - are another type of information systems in which, with the help of rather complex queries, data is selected and analyzed in various sections: temporal, geographical and other indicators.

Extensive class information and reference systems based on hypertext documents and multimedia. Such information systems have received the greatest development on the Internet.

Class office information systems aims to translate paper documents into electronic form, office automation and document management.

Classification by way of organization

According to the method of organization, group and corporate information systems are divided into following classes:

1. systems based on file-server architecture;

2. systems based on client-server architecture;

3. systems based on a multi-level architecture;

4. systems based on Internet/Intranet technologies.

In any information system, it is possible to identify the necessary functional components that help to understand the limitations of various information system architectures.

File server architecture only extracts data from files so that additional users and applications add only a minor load on the CPU. Each new client adds processing power to the network.

Client-server architecture is designed to solve the problems of file server applications by separating application components and placing them where they will function most efficiently. A feature of the client-server architecture is the use of dedicated database servers that understand queries in the Structured Query Language SQL (Structured Query Language) and search, sort and aggregate information.

Currently, the client-server architecture has been recognized and widely used as a way to organize applications for workgroups and enterprise-level information systems. This organization of work increases the efficiency of application execution by using the capabilities of the database server, offloading the network and ensuring data integrity control.

Layered architecture became the development of the client-server architecture and in its classical form consists of three levels:

1. The lower layer is the client applications that have a programming interface to call the application in the middle layer;

2. the middle layer is an application server;

3. The top level is a remote specialized database server.

The three-tier architecture further balances the load across different hosts and networks, promotes specialization of application development tools, and eliminates the shortcomings of the two-tier client-server model.

In development technologies Internet/intranet the main emphasis so far is on the development of software tools. At the same time, there is a lack of developed tools for developing applications that work with databases. A compromise solution for creating convenient and easy-to-use and maintain information systems that work effectively with databases was the combination of Internet / Intranet technology with a multi-level architecture. In this case, the structure of the information application takes the following form: browser - application server - database server - dynamic page server - web server.

According to the nature of the stored information, databases are divided into factual and documentaries. If we draw an analogy with the examples of information repositories described above, then factographic databases are file cabinets, and documentary databases are archives. Factual databases store brief information in a strictly defined format. Documentary databases contain all sorts of documents. And it can be not only text documents but also graphics, video and sound (multimedia).

Automated control system (ACS) is a set of hardware and software, together with organizational structures(individual people or a team), providing management of an object (complex) in an industrial, scientific or social environment.

Allocate education management information systems (For example, personnel, applicant, student, library programs). Automated systems for scientific research(ASNI), which are software and hardware systems that process data coming from various kinds experimental facilities and measuring instruments, and on the basis of their analysis facilitate the discovery of new effects and patterns. Computer-aided design systems and geographic information systems.

system artificial intelligence, built on the basis of high-quality special knowledge about a certain subject area (obtained from experts - specialists in this field), is called an expert system. Expert systems - one of the few types of artificial intelligence systems - are widely used and have found practical application. There are expert systems for military affairs, geology, engineering, computer science, space technology, mathematics, medicine, meteorology, industry, agriculture, management, physics, chemistry, electronics, law, etc. And only the fact that expert systems remain very complex, expensive, and, most importantly, highly specialized programs, hinders their even wider distribution.

Expert systems (ES) are computer programs, created to perform those types of activities that are within the power of a human expert. They work in a way that mimics the behavior of a human expert, and differs significantly from precise, well-reasoned algorithms and does not resemble the mathematical procedures of most traditional developments.

1. IP life cycle and its structure. 2

1.1 Stages of the IS life cycle.. 3

1.2 IS Life Cycle Standards.. 4

2. Life cycle models. 6

2.1 Types of IS life cycle models .. 6

2.2 Advantages and disadvantages of IS life cycle models.. 8

3. Processes of the IP life cycle .............................................. .................. eleven

3.1 Basic life cycle processes. eleven

3.2 Supporting life cycle processes. thirteen

3.3 Organizational processes.. 14

List of used literature.. 16

The life cycle of an information system is a period of time that begins from the moment a decision is made on the need to create an information system and ends at the moment of its complete withdrawal from operation.

The concept of the life cycle is one of the basic concepts of the methodology for designing information systems.

The information systems design methodology describes the process of creating and maintaining systems in the form of an IS life cycle (LC), representing it as a certain sequence of stages and processes performed on them. For each stage, the composition and sequence of work performed, the results obtained, the methods and means necessary to perform the work, the roles and responsibilities of participants, etc. are determined. Such a formal description of the life cycle of IS makes it possible to plan and organize the process of collective development and ensure the management of this process.

The complete life cycle of an information system includes, as a rule, strategic planning, analysis, design, implementation, implementation and operation. In general, the life cycle can in turn be divided into a number of stages. In principle, this division into stages is quite arbitrary. We will consider one of the options for such a division offered by Rational Software Corporation, one of the leading companies in the software market for information systems development tools (among which the Rational Rose universal CASE tool deserves great popularity).

1.1 Stages of the IP life cycle

Stage - part of the process of creating an IS, limited by a certain time frame and ending with the release of a specific product (models, software components, documentation), determined by the requirements specified for this stage. The relationship between processes and stages is also determined by the IS life cycle model used.

According to the methodology offered by Rational Software, the life cycle of an information system is divided into four stages.

The boundaries of each stage are determined by certain points in time at which it is necessary to take certain critical decisions and therefore achieve certain key objectives.

1) Initial stage

On the initial stage the scope of the system is established and the boundary conditions are determined. To do this, it is necessary to identify all external objects with which the developed system should interact, and to determine the nature of this interaction at a high level. At the initial stage, all the functional capabilities of the system are identified and a description of the most significant of them is made.

2) Refinement stage

At the refinement stage, an analysis of the application area is carried out, and the architectural basis of the information system is developed.

When making any decisions regarding the architecture of the system, it is necessary to take into account the system being developed as a whole. This means that it is necessary to describe most of the functionality of the system and take into account the relationships between its individual components.

At the end of the clarification stage, an analysis is carried out architectural solutions and ways to eliminate the main risk factors in the project.

3) Construction stage

At the design stage, a finished product is developed, ready for transfer to the user.

At the end of this stage, the performance of the developed software is determined.

4) Commissioning stage

At the stage of commissioning, the developed software is transferred to users. When operating the developed system in real conditions, various kinds of problems often arise that require additional work to make adjustments to the developed product. This is usually associated with the detection of errors and flaws.

At the end of the handover phase, it must be determined whether the development objectives have been achieved or not.

1.2 IP life cycle standards

Modern networks are developed on the basis of standards, which makes it possible to ensure, firstly, their high efficiency and, secondly, the possibility of their interaction with each other.

Among the most famous standards are the following:

GOST 34.601-90 - applies to automated systems and establishes the stages and stages of their creation. In addition, the standard contains a description of the scope of work at each stage. Stages and stages of work, enshrined in the standard, are more in line with the cascade life cycle model.

ISO / IEC 12207 (International Organization of Standardization / International Electrotechnical Commission) 1995 - a standard for processes and life cycle organization. Applies to all types of custom software. The standard does not contain descriptions of phases, stages and steps.

The Rational Unified Process (RUP) offers an iterative development model that includes four phases: start, explore, build, and deploy. Each phase can be broken down into stages (iterations) that result in a release for internal or external use. The passage through four main phases is called the development cycle, each cycle ends with the generation of a version of the system. If after that the work on the project does not stop, then the resulting product continues to develop and again passes through the same phases. The essence of work within the framework of RUP is the creation and maintenance of models based on UML.

Microsoft Solution Framework (MSF) is similar to RUP, also includes four phases: analysis, design, development, stabilization, is iterative, involves the use of object-oriented modeling. MSF is more focused on business application development than RUP.

Extreme Programming (XP). Extreme Programming (the newest among the methodologies under consideration) was formed in 1996. The methodology is based on teamwork, effective communication between the customer and the contractor throughout the entire project for the development of IP, and development is carried out using successive highly refined prototypes.

2. Life cycle models

The IS life cycle model is a structure that determines the sequence of execution and the relationship of processes, actions and tasks throughout the life cycle. The life cycle model depends on the specifics, scale and complexity of the project and the specific conditions in which the system is created and operates.

The LC IS model includes:

the results of the work at each stage;

key events - points of completion of work and decision-making.

The life cycle model reflects various states system, starting from the moment the need for this IS arises and ending with the moment it is completely out of use.

2.1 Types of IP life cycle models

The following life cycle models are currently known and used:

The cascade model (Fig. 2.1) provides for the sequential execution of all project stages in a strictly fixed order. The transition to the next stage means the complete completion of the work at the previous stage.

Staged model with intermediate control (Fig. 2.2). IS development is carried out in iterations with cycles feedback between stages. Inter-stage adjustments make it possible to take into account the real mutual influence of development results on various stages; the lifetime of each of the stages is stretched for the entire development period.

Spiral model (Fig. 2.3). At each turn of the spiral, the next version of the product is created, the requirements of the project are specified, its quality is determined, and the work of the next turn is planned. Special attention is given to the initial stages of development - analysis and design, where the feasibility of certain technical solutions is checked and justified through the creation of prototypes (prototyping).

Rice. 2.1. Cascade model of life cycle of IP

Rice. 2.2. Staged model with intermediate control

Rice. 2.3. Spiral model of life cycle of IP

In practice, two main life cycle models are most widely used:

cascade model (typical for the period 1970-1985);

spiral model (typical for the period after 1986.).

2.2 Advantages and disadvantages of IP life cycle models

In early projects of fairly simple ICs, each application was a single, functionally and informationally independent unit. For developing this type of application, the cascade method proved to be effective. Each stage ended after full implementation and documentation of all planned works.

The life cycle of an information system is a period of time that begins from the moment a decision is made on the need to create an information system and ends at the moment of its complete withdrawal from operation.

The concept of the life cycle is one of the basic concepts of the methodology for designing information systems.

The information systems design methodology describes the process of creating and maintaining systems in the form of an IS life cycle (LC), representing it as a certain sequence of stages and processes performed on them. For each stage, the composition and sequence of work performed, the results obtained, the methods and means necessary to perform the work, the roles and responsibilities of participants, etc. are determined. Such a formal description of the life cycle of IS makes it possible to plan and organize the process of collective development and ensure the management of this process.

The complete life cycle of an information system includes, as a rule, strategic planning, analysis, design, implementation, implementation and operation. In general, the life cycle can in turn be divided into a number of stages. In principle, this division into stages is quite arbitrary. We will consider one of the options for such a division, offered by Rational Software Corporation, one of the leading companies in the software market for information systems development tools (among which the Rational Rose universal CASE tool deserves great popularity).

IP life cycle stages

Stage - part of the process of creating an IS, limited by a certain time frame and ending with the release of a specific product (models, software components, documentation), determined by the requirements specified for this stage. The relationship between processes and stages is also determined by the IS life cycle model used.

According to the methodology offered by Rational Software, the life cycle of an information system is divided into four stages.

The boundaries of each stage are defined by certain points in time at which it is necessary to make certain critical decisions and, therefore, achieve certain key goals.

1) Initial stage

At the initial stage, the scope of the system is established and the boundary conditions are determined. To do this, it is necessary to identify all external objects with which the developed system should interact, and to determine the nature of this interaction at a high level. At the initial stage, all the functional capabilities of the system are identified and a description of the most significant of them is made.

2) Refinement stage

At the refinement stage, an analysis of the application area is carried out, and the architectural basis of the information system is developed.

When making any decisions regarding the architecture of the system, it is necessary to take into account the system being developed as a whole. This means that it is necessary to describe most of the functionality of the system and take into account the relationships between its individual components.

At the end of the clarification stage, an analysis of architectural solutions and ways to eliminate the main risk factors in the project is carried out.

3) Construction stage

At the design stage, a finished product is developed, ready for transfer to the user.

At the end of this stage, the performance of the developed software is determined.

4) Commissioning stage

At the stage of commissioning, the developed software is transferred to users. When operating the developed system in real conditions, various kinds of problems often arise that require additional work to make adjustments to the developed product. This is usually associated with the detection of errors and flaws.

At the end of the handover phase, it must be determined whether the development objectives have been achieved or not.

IP Life Cycle Standards

Modern networks are developed on the basis of standards, which makes it possible to ensure, firstly, their high efficiency and, secondly, the possibility of their interaction with each other.

Among the most famous standards are the following:

GOST 34.601-90 - applies to automated systems and establishes the stages and stages of their creation. In addition, the standard contains a description of the scope of work at each stage. Stages and stages of work, enshrined in the standard, are more in line with the cascade life cycle model.

ISO / IEC 12207 (International Organization of Standardization / International Electrotechnical Commission) 1995 - a standard for processes and life cycle organization. Applies to all types of custom software. The standard does not contain descriptions of phases, stages and steps.

The Rational Unified Process (RUP) offers an iterative development model that includes four phases: start, explore, build, and deploy. Each phase can be broken down into stages (iterations) that result in a release for internal or external use. The passage through four main phases is called the development cycle, each cycle ends with the generation of a version of the system. If after that the work on the project does not stop, then the resulting product continues to develop and again passes through the same phases. The essence of work within the framework of RUP is the creation and maintenance of models based on UML.

Microsoft Solution Framework (MSF) is similar to RUP, also includes four phases: analysis, design, development, stabilization, is iterative, involves the use of object-oriented modeling. MSF is more focused on business application development than RUP.

Extreme Programming (XP). Extreme Programming (the newest among the methodologies under consideration) was formed in 1996. The methodology is based on teamwork, effective communication between the customer and the contractor throughout the entire IP development project, and development is carried out using successively refined prototypes.

spiral life cycle cascading