OS. Features of the Windows operating system

2.1.1 Windows performs the following main functions:

· Convenient, clear graphical user interface.

· Multitasking, i.e. running multiple programs at the same time.

· Unification of the use of computer hardware resources.

2.1.2 Features of Windows 7:

Components of a custom Windows interface 7 are windows with controls, taskbar and context menu, and the main input devices are the mouse, keyboard, joystick, (if the computer uses touch screen, then the input is a display that converts a tap or touch on the screen into a command).

Windows 7 is fully introduced for the first time multi-sensor technology.

When you start Windows 7, the desktop appears on the screen. Desktop is the main window of the graphical user environment (GUI). By default, in the Windows 7 configuration, the desktop displays background image and only one icon (Trash).

If necessary, icons and shortcuts of programs, folders and files, as well as gadgets (mini-applications that are distributed free of charge, for example, windows gadgets MediaCenter or weather forecast), In Windows 7, gadgets can be placed anywhere on the desktop.

During operation, the desktop displays running programs and open folders that cover the background image of the table with icons and gadgets.

To change the desktop interface, themes are used, which include the desktop background, window color, sounds, and screensaver. The Windows 7 operating system offers the following themes: basic (simplified and classic), contrast, and Aero.

To enable a theme, right-click on the desktop and select Personalize from the context menu. So Windows 7 has the ability to customize your desktop with new themes, slide shows, and gadgets.

In Windows 7, you can perform a quick search (Windows Search) more documents, videos, pictures and music. Entering the required query in the "Search programs and files" search box on the Start menu will immediately display a list of matching documents found on the computer.

One of the main purposes of the taskbar is to switch between open applications. The taskbar consists of the following components: the Start button, the application icon area, combined with the panel quick start, notification area, a minimize all windows button that is used to both minimize windows and preview the desktop using the AeroPeek effect.

Figure 12 Operating system taskbar Windows systems 7

AeroPeek feature in Windows 7 like x-rays, which allows you to shine through the contents of all open windows on the desktop. The AeroPeek feature allows you to temporarily view the desktop (view the background image, icons, and gadgets on the desktop) under all open application windows when you hover over the Minimize All Windows button located on the right side of the taskbar.

When you click on the button with the left mouse button, the windows are minimized. When you click again, the windows expand. To enable AeroPeek, in the Taskbar and Start Menu Properties dialog box, select the Use AeroPeek to preview the desktop check box.

Pinning apps on the taskbar. Application icons are displayed on the taskbar by default Internet Explorer, Player Windows Media and Explorer. When you start other applications, the corresponding icons on the taskbar also appear, and when you close them, the icons disappear. To quickly launch applications, you can pin them to the taskbar. To do this, right-click the application icon from the desktop to the taskbar.

View thumbnails of open application windows. When selecting the "Always group, hide labels" mode in the dialog box Properties the taskbar and start menu on the taskbar will group open windows. If you place the mouse pointer over a minimized program icon while the Aero theme is enabled, a group of miniature windows (thumbnails) of previewing application windows will be displayed.

Jump Lists- it new feature in Windows 7. Right-clicking on the icon in the taskbar will open the jump list. Each application has its own jump list. This feature allows you to quickly jump to frequently used documents or recent files.

notification area. The default notification area displays icons: Show hidden icons, Network, Speakers, Action Center, Power (laptop only), and clock.

To work with windows in Windows 7, there are functions called AeroShake and AeroSnap.

Aeroshake function. The AeroShake function allows you to minimize all open windows, except for the window that is being shaken by the mouse. To do this, you need to place the mouse pointer on the title bar of the application window and, while holding the left mouse button, quickly move the mouse manipulator left - right or up - down, i.e. shake her. When you shake the mouse again, all minimized windows return to their original position.

AeroSnap feature. The Snap function provides quick resizing of open windows by dragging them to the screen borders. If you place the mouse pointer on the title bar of the application window and, while holding down the left mouse button, drag the window to the left or right border of the screen, then it will take up exactly half of the user's desktop. To maximize a window, you must drag it with the mouse by the title bar up the screen, when the mouse cursor reaches the top side of the screen, the window will expand.

2.2 Programs and services built into Windows XP/7:

Table 35 Programs and services built into Windows XP/7

OS families Windows is a 32-bit operating system that provides multi-tasking and multi-threaded application processing. They support user-friendly graphic user interface, the ability to work in protected mode, compatibility with programs real mode and networking capabilities. Windows implements plug and play technology, allows long file names, and provides improved resiliency.

32-bit means that operations on 32-bit data are faster here than on 16-bit ones. 32-bit Windows applications run in their own address space, which is not accessible to other programs. This protects applications from each other's errors. If one application fails, the other continues to function normally. A failed application can be terminated.

multitasking provides the ability to work with multiple applications in parallel. While one of them is busy, for example, printing a document on a printer or receiving Email from Internet networks, the other can recalculate the spreadsheet or do other useful work.

Multithreading allows specially designed applications to run multiple of their own processes at the same time. For example, when working with a multi-threaded spreadsheet, the user will be able to recalculate in one spreadsheet while another one is being printed and loaded into memory by a third. While one thread is waiting, for example, to complete a communication operation with a slow peripheral, the other can continue to do its work.

A hallmark of Windows is its object-oriented approach to building a system. At the user level, the object approach is expressed in the fact that the interface is a semblance of the real world, and working with the machine is reduced to actions with familiar objects. So, folders can be opened, put into a briefcase, documents can be viewed, corrected, shifted from one place to another, thrown into the trash, fax or letter can be sent to the addressee, etc. The user works with tasks and applications in the same way as with documents on your desk. The object-oriented approach is implemented through the model desktop– primary Windows object. After Windows boot it is displayed on the screen. Various objects can be located on the desktop: programs, folders with documents (texts, pictures, tables), shortcuts to programs or folders.

Labels provide access to a program or document from multiple locations without creating multiple physical copies of the file. On the desktop, you can put not only the icons of applications and individual documents, but also folders. Folders are another name for directories.

A significant innovation in Windows is task bar. Despite the small functionality, it makes the multitasking mechanism visual and greatly speeds up the process of switching between applications. Externally, the taskbar is a strip, usually located at the bottom of the screen, which contains application buttons and the Start button. On the right side of it, there is usually a clock and small icons of programs active in this moment.

Windows provides work with audio and video files of various formats. A significant achievement of Windows was the software for computer communications built into the system. Communication Windows tools designed for ordinary users and do not require special knowledge. These tools include LAN and WAN capabilities, modem setup, email connectivity, and more.

The Windows operating system makes extensive use of the mouse when working with windows and applications. Typically, the mouse is used to select fragments of text or graphic objects, check and uncheck boxes, select menu commands, toolbar buttons, manipulate controls in dialogs, "scroll" documents in windows.

Windows is actively used and right button mice. By placing the pointer over the object of interest and right-clicking, you can expand context menu A containing the most common commands applicable to this object.

When shutting down, you cannot simply turn off the computer without shutting down the system properly - this can lead to the loss of some unsaved data. To properly shut down, you must save data in all applications that the user has worked with, close all previously running DOS applications, open the Start button menu and select the Shut Down command.

Windows is a family of Microsoft operating systems. As of May 2013, about 91% were running Windows personal computers. Windows operating systems run on most hardware platforms. Its distinguishing features are: graphical user interface, preemptive multitasking, support for long filenames, automatic detection and configuration peripherals(Plug and Play).

The graphical shell of the Windows OS provides user interaction with the computer in the form of a dialogue using input and output on the display screen. graphic information, control programs using icons, menus, windows, panels and other controls.

Main elements GUI are: Desktop and Task bar with button Start. The manipulator is the main program control device. mouse.

The mouse pointer is used to select menu commands, move objects, select text fragments, and so on. The appearance of the mouse pointer on the screen depends on the operation being performed:

· when selecting an object, the pointer looks like an arrow pointing upwards at an angle;

In the document window, the pointer resembles the Latin letter I;

· if the operating system is busy performing some operations and cannot work with the user, the pointer has the shape of an hourglass.

To select an object on the screen, place the pointer on it and then press the left mouse button.

Click(momentary button press) is one of the basic mouse operations. To do this, quickly press and release the mouse button. Click to select an object in the program window, select the desired command in the menu, etc. Right-clicking on Windows items displays a context menu.

double click the left button is produced when the mouse pointer is positioned on a certain object and is used, as a rule, to open a file.

Dragging an object (Drag and Drop) is an operation that changes the location of an object. To perform it, you need to place the pointer on the desired object (icon, folder, file), press the left mouse button and, without releasing it, move the mouse so that this object moves with it.

ü Each menu item marked with 4 has a submenu that opens when you click on that menu item. A submenu usually expands from top to bottom and is therefore called falling. You select the required item (operation) in the submenu and activate it also with a mouse click. In order to leave the menu, you need to move the mouse pointer to the open part of the desktop (or program window) and click the mouse.

ü Sub-menu items are available to the user if they are displayed in black, and are not available if they are displayed in gray.

ü An ellipsis after the name of the submenu item means that additional instructions are required to execute this command, which will be entered by the user using the dialog box.

ü When you activate a menu item (submenu) that does not have any marks to the right of the name, the program of the same name is launched in a separate window.

There are three buttons in the upper right corner of the window:

§ program window minimization button with an underscore (left button). Clicking this button minimizes the window to the icon shown on the Taskbars;

§ window resize button(middle button). If the button looks like a page, then clicking on it expands the window to full screen. If the button looks like two pages, then clicking on it minimizes the window to such a size that the borders of the window become visible;

§ on the exit button(right button) oblique cross placed S. Clicking this button terminates the program.

All of the above conventions and actions apply to all Windows applications as well.

The most common Windows application is MS office . This office suite of applications has been improved for about 20 years. The first version of the suite, numbered 3.0, was released in 1992 and won a fierce competition with two other office suites. WordPerfect Suite companies Novell Inc. , in 1996 sold to the company corel , and Lotus SmartSuite companies Lotus Developers which ceased to exist in 1995.

Despite the advent of open office suites openoffice.org and LibreOffice, MS Office maintains its leading position in the market. While the governments of several European countries have recommended openoffice.org and libreoffice , as office suites for government organizations

MS office comes in several editions. Differences between editions in the package and price. One of the most complete editions contains:

MS Word is a word processor. Allows you to prepare documents of varying complexity. The product occupies a leading position in the market and is used as a standard in the workflow of most enterprises.

MS Excel - spreadsheet processor. Supports all the necessary functions to create spreadsheets of any complexity. Occupies a leading position in the market.

MS Outlook is a personal communicator. It includes: calendar, task scheduler, notes, email manager, address book. Supports network collaboration.

MS PowerPoint is an application for preparing presentations.

MS Access is a database management application.

MS Publisher is an application for preparing publications.

MS OneNote is an application for taking notes and managing them (organizer).

MS Groove - Provides a space for users to hold online meetings, discuss shared projects, and more.

MS SharePoint Designer is an HTML editor and web design program.

MS Picture Manager is an application for working with pictures.

MS InfoPath, a data collection and management application, simplifies the process of gathering information.

Various editions of MS Office 2010:

MS Office supports scripts and macros written in the Visual Basic for Applications (VBA) programming language - a slightly simplified implementation language Visual Basic, built into the MS Office product line.

The following Windows applications are also used for office purposes:

MS Visio - building application block diagrams and plans from ready-made elements and templates.

MS Project is a project management application.

Microsoft Word (often just Word) is a word processor designed to create, view and edit text documents. Available as part of a package Microsoft office. Since 1989, 11 versions (editions) of MS Word have been released to work under Windows.

MS Word is the most popular currently used word processors. The binary format of his documents (extension doc) is the standard de facto , and many competing programs maintain compatibility with this format. Document Format different versions Word is changing. Formatting that looks normal in one version may not appear in previous versions program, however, there is a limited ability to save a document with the loss of part of the formatting for opening in older versions of the product. Latest Versions MS Word 2007/2010/2013 use the default XML-based format (extension docx).

Word enhances the user experience through the use of a built-in macro language (from version Word 97 applies VBA). However, this created the possibility of writing viruses embedded in documents (the so-called. macro viruses). In this regard, it is recommended to always set highest level security settings when using Word(Menu item: Service/Macro/Security) and use anti-virus programs.

Word has a range of complex service functions. Performs:

Search and, if necessary, replace individual words or text fragments;

Spell check and hyphenation;

Automatic insertion of a table of contents, bibliography, subject index, links, incl. hyperlinks, etc.;

Protecting documents from unauthorized access

Microsoft Excel Microsoft's spreadsheet program. It provides ample opportunities for economic, statistical and technical calculations, has graphical tools for visual presentation and analysis of the results of tabular calculations, allows you to use the VBA programming language to implement non-standard functions. It also provides the ability to protect all or part of the data from unauthorized access.

Excel is part of MS Office and today is one of the most popular apps in the world. Excel document has an .xls extension (.xlsx in MS Excel 2007/2010/2013) and is called a workbook. The workbook consists of separate sheets. You can switch between sheets using the tabs at the bottom of the window.

Each sheet is a table. The table consists of columns and rows. The number of columns in the sheet is 16384 (2 14), and the number of rows is 1048576 (2 20). The number of sheets in a book is limited by the available random access memory(default 3 sheets). The column width is 255 characters.

The accuracy of data presentation is no more than 15 digits, and the allowable date in the calculations is not earlier than January 1, 1900.

MS Excel allows you to solve complex mathematical problems using built-in procedures − superstructures. The most useful ones Finding a solution and Data analysis.

Add-in "Search for a solution » solves optimization problems:

Non-linear generalized downgrading gradient method, which is used for smooth non-linear problems;

Simplex method for linear programming problems (Nobel Prize in Economics 1975);

An evolutionary method for nonsmooth problems.

Holding statistical analysis can be accelerated using the Analysis ToolPak add-in. To analyze data with this package, you must provide input data and select options; the calculation will be performed using a suitable statistical macro function and the result will be placed in the output range. Some tools allow you to present the results of the analysis in a graphical form.

The analysis package implements various methods for assessing the reliability of differences (T-tests, F- and Z-tests), dispersion, correlation and regression analysis and a number of other widely used statistical procedures.

Microsoft Visio- vector graphics editor, a diagram and block diagram editor for Windows. Visio was originally developed and published by Visio Corp. Microsoft acquired the company in 2000, rebranded and incorporated the product into MS Office.

The app helps users simplify the presentation of complex information with easy-to-understand diagrams. Visio includes stencil libraries for diagrams from most subject areas, diagrams local networks, organization charts, flow charts, and general multi-purpose diagrams.

There are many types of Visio drawings, but there are three basic steps to creating any of them.

1. Select and open a template.
2. Drag and drop shapes.
3. Adding text to shapes.

MS Project is a project management program developed and marketed by Microsoft Corporation.

MS Project was created to help the project manager (PMI) in developing a project execution plan, allocating resources to tasks, tracking progress and analyzing the amount of work ahead. MS Project creates critical path schedules. Schedules can be drawn up taking into account the resources used. The chain is visualized in a Gantt chart.

The Gantt chart is a bar chart placed on a horizontal timeline. Each segment corresponds to a separate project, task or subtask. The projects, tasks, and subtasks that make up the plan are placed vertically. The start, end, and length of the segment on the timeline correspond to the start, end, and duration of the task.

MS Project, with 20 million users, is essentially a monopoly. The most obvious advantages of the product are related to the fact that it is included in MS Office. This provides the following advantages, common to all MS Office products:

ü the same short user training time as with other MS Office programs;

ü rich customization options in style Excel formulas(the product itself is designed in an interface close to Excel);

ü the ability to adapt the product to your specifics by programming or buying ready-made solutions created on the basis of VBA.

You can enter resources into a project and assign them to tasks to determine which resource is responsible for completing which assignment. This helps not only plan the recruitment of personnel for the project, but also calculate the amount of equipment required and the volume Supplies. When entering resources calendar plans Tasks are supplemented with the following resource information:

s Labor

s Units

s Work time in calendar units

MS PowerPoint- a program for creating and conducting presentations, which is part of MS Office. Today, PowerPoint is the most popular tool for visual presentation of information.

The main problems that arise when creating a presentation are not technical, but content and design. The content side is entirely on the conscience of the author of the presentation, and there are specific recommendations for design:

s font size: 24-52 pt (heading), 18-32 pt (plain text);

s font color and background color should contrast (the text should be legible, but not hurt the eyes);

s font type: smooth sans-serif (Arial) for body text, decorative fonts can sometimes be used for headings if widely available;

s italics, underlining, bold, capital letters are recommended to be used only for semantic highlighting of a text fragment;

s the color scheme should consist of no more than two or three colors that can be combined with each other;

s illustrations are designed to supplement textual information, to present it in a visual form;

s information blocks should be placed horizontally, blocks related in meaning - from left to right;

s information blocks should not be too many (about 3-6)

MS Access– relational database management system. It has a wide range of features, including linked queries, links to external tables and databases. Thanks to VBA language, you can write applications that work with databases in Access.

The term "relational" means that the theory is based on a mathematical concept attitude. The word table is often used as an informal synonym for the term "relationship".

Information in relational database data is presented in the form of a set of related tables or one tables, the lines of which characterize the combined properties of individual objects that make up the table, and are called records Database. The columns of the table describe the individual properties of each object and are called fields Database.

Access allows you to create links between tables, which allows you to share data from different tables and thereby avoid unnecessary duplication of data, save computer memory, and increase the speed and accuracy of information processing.

The convenience of manipulation and the speed of information processing in the DBMS depend on how fully the specificity of the stored information is reflected in the database. To do this, the information placed in the database fields must be assigned to one of nine types:

· text fields designed to store character information. Text fields can contain letters, numbers, punctuation, spaces, and other characters. Text fields must not exceed 255 characters;

· memo fields designed to store long (up to 64000 characters) texts. This type of field can store text containing multiple sentences or paragraphs. However, the number of operations with MEMO fields is less than the number of manipulations with text fields;

· numeric fields are intended to store numeric values ​​that are not monetary amounts. Numeric fields, in turn, are:

o byte– for storing integers from 0 to 255;

o whole– for storing integers from -32768 to 32767;

o long integer– for storing integers from -2147483648 to 2147483647;

o single floating point- for storing fractional numbers with six decimal places;

o double floating point- for storing fractional numbers with ten decimal places;

· date/time fields designed to store date and time information. They allow you to manipulate data, for example, determine the time interval that has elapsed from one date to another. There are several date/time representation formats;

· money fields are numeric fields of a special format and are intended for storing information about monetary amounts and for operations with them. When working with monetary amounts, Acces uses the types of currencies that are set by default in Windows environment;

· field Counter– a special type of numeric field, the value of which is automatically increased when entered into the table for each new record. The first entry is assigned the value 1, the second entry is assigned the value 2, and so on. The value assigned to the entry entered can no longer be changed;

· boolean fields designed to store information that takes one of two values ​​"Yes" or "No" (Yes / No);

· OLE fields contain information created by others Windows applications, including graphics. OLE field sizes are limited by the hardware capabilities of the computer;

· hyperlink fields are intended for storing addresses-links to files on hard disks or to pages on the Internet (Intranet).

Despite its undeniable advantages, the Access DBMS is limited in its ability to work with large amounts of information. In Access, the maximum table file size is 2 GB, and the number of fields in tables and reports - up to 255. The number of characters in a text field is no more than 255, and in a record (except for MEMO and OLE fields) - up to 4000.

Access, when working with a database, interacts differently with the hard drive than other programs. A new version of the modified entry is written to disk as soon as the keyboard cursor is moved to another line.

Main components of MS Access:

Table builder;

Screen form builder;

Query Builder

Printable Report Builder.

Today, a huge part of the world's population interacts with computers on an ongoing basis, someone is obligated to work, someone is looking for information on the Web, and someone just spends time playing games. Everyone has their own needs, which means that the computer must meet them. And if we are talking about “hardware” (the technical component of a computer), then everything is less clear: the newer, the better. But here is the “software” ( software) part requires special attention.

Each computer runs on a specific operating system, of which there are a great many, each of which is suitable for certain tasks, available equipment, and so on. Therefore, an important factor is the choice of this operating system.

There is a fairly massive list of operating systems, but this article will focus on three pillars that have greatly influenced the industry and occupy the bulk of all operating systems: Windows, MacOS and Linux.

Proprietary operating systems

To begin with, it is worth clarifying that there are proprietary OSes, those that are distributed under the manufacturer's license. These include Windows, which are listed below, and MacOS. Even though both systems can be downloaded on the Web (stealed), the right thing to do is to purchase a license from the distribution company and activate it.

The advantage of such systems is their development, a huge amount of high-quality software and competent technical support that will help in case of problems.

“Free” operating systems

These include almost the entire Linux family, with the exception of some developments with accounting or other professional software. These operating systems can be downloaded absolutely free of charge and installed on any computer without a twinge of conscience.

Such systems are created by independent developers together with the community, therefore, in most cases, the quality of programs leaves much to be desired, but such systems are much more secure and work more stable than their proprietary competitors.

Windows

Absolutely everyone who has ever dealt with a computer knows about this Microsoft product. In particular, this applies to the super-successful release of Windows 7. List of operating Microsoft systems spans ten generations. They are extremely popular all over the world and occupy almost 90% of the market. Which speaks of unparalleled leadership.

• Windows XP;
• Windows Vista;
• Windows 7;
• Windows 8;
• Windows 10;

The list intentionally starts with Windows XP, as it is the most old version which has remained in use to this day.

Chrome OS

An underdeveloped product from Google, which is limited only to web applications and the browser of the same name. This system is not competitive with Windows and Mac, but is made with an eye to the future, when web interfaces can replace "real" software. Installed by default on all Chromebooks.

Installing multiple systems and using virtual machines

Since each platform has its pros and cons, it is often necessary to work with several at once. Computer developers know this, so they offer users the opportunity to install two or three systems on a disk at once.

This is done simply. All you need is a system distribution kit (a disk or flash drive with the installation material loaded on them) and free space on the hard drive. All modern operating systems offer to allocate space during installation and create a boot mechanism that will show a list of operating systems when the computer boots. Everything is done in a semi-automatic mode and is within the power of any user.

On the Apple computers available special utility- BootCamp which is designed to be simple and seamless Windows installation next to macOS.

There is another way - installing a virtual system inside a real one. For this, programs are used: VmWare and VirtualBox, which can emulate the operation of a full-fledged computer and run operating systems.

Instead of a conclusion

The list of operating systems for the computer is not limited to the above. There are a lot of products from different companies, but they are all quite specific and do not deserve the attention of an ordinary user. The choice should be made between Windows, MacOS and Linux, as they can cover most of the needs and are quite easy to learn.

Windows operating system features.

Standardization of the user interface (techniques and methods for managing hardware and software) GUI user interface in Windows is based on the idea of ​​a window interface, which is also adopted in a number of other modern operating systems (for example, UNIX). Each program has its own window, in which messages are exchanged with the user. For clarity, Windows widely uses icons (pictograms) depicting individual programs;

optimal management of large-capacity RAM;

the ability to easily connect new external devices(plug and play) The operating system can programmatically determine the purpose of such a device, find out what options for its settings are possible, and choose the most suitable one;

integration of program functions (the ability to use objects created by means of another program in a particular program). It is possible to exchange data between applications, which allows, for example, information created in a spreadsheet to be transferred to a text document via the clipboard. OLE technology;

multitasking (the ability to simultaneously run multiple applications and easily switch from one program to another). Multitasking mode allows you to run several applications at the same time, for example, a word processor, a database, a game and switch between them;

micronucleus architecture.

The current trend in operating system development is to move much of the system code down to the user level while minimizing the kernel. We are talking about an approach to building a kernel, called the microkernel architecture (microkernel architecture) of the operating system, when most of its components are independent programs. In this case, the interaction between them is provided by a special kernel module called the microkernel. The microkernel runs in privileged mode and handles interprogram communication, CPU usage scheduling, primary interrupt handling, I/O operations, and basic memory management.

Rice. 1.4 Microkernel operating system architecture

The remaining components of the system communicate with each other by passing messages through the microkernel.

The main advantage of the microkernel architecture is the high degree of modularity of the operating system kernel. This greatly simplifies adding new components to it. In a microkernel operating system, you can load and unload new drivers, file systems, etc. without interrupting its operation. The process of debugging kernel components is greatly simplified, since a new version drivers can be loaded without restarting the entire operating system. The components of the operating system kernel are not fundamentally different from user programs, so you can use the usual tools to debug them. At the same time, the microkernel architecture of the operating system introduces additional overhead associated with message passing, which significantly affects performance. In order for a microkernel operating system to be as fast as monolithic kernel operating systems, it is necessary to carefully design the partitioning of the system into components, trying to minimize the interaction between them. Thus, the main difficulty in creating microkernel operating systems is the need for very careful design.

Object Oriented Approach

Although micronucleus technology laid the foundations modular systems able to develop in a regular manner, it has not been able to fully ensure the expansion of systems. Currently, this goal is most consistent with an object-oriented approach, in which each software component is functionally isolated from others.

The main concept of this approach is "object". An object is a unit of programs and data that interacts with other objects by receiving and transmitting messages. An object can be a representation of some particular thing - application program or a document, as well as some abstractions - a process, an event.

Programs (functions) of an object determine the list of actions that can be performed on the data of this object. A client object can access another object by sending a message requesting some function of the server object.

Objects can describe the entities they represent in varying degrees of detail. To ensure continuity in the transition to a more detailed description, developers are offered a mechanism for inheriting the properties of existing objects, that is, a mechanism that allows generating more specific objects from more general ones. For example, given a "text document" object, a developer can easily create a "text document in Word 6.0" object by adding the appropriate property to the base object. The inheritance mechanism allows you to create a hierarchy of objects, in which each lower-level object acquires all the properties of its ancestor.

The internal data structure of an object is hidden from view. You cannot arbitrarily change the data of an object. In order to get data from an object or put data into an object, you must call the corresponding object functions. This isolates the object from the code that uses it. The developer can access the functions of other objects, or build new objects by inheriting the properties of other objects, without knowing anything about how they are constructed. This property is called encapsulation.

Thus, the object appears to the outside world as a "black box" with a well-defined interface. From the point of view of the developer using the object, as long as the external response of the object remains unchanged, no change in the internal implementation matters. This makes it possible to easily replace one implementation of an object with another, for example, in the event of a change in hardware; however, the complex software environment in which the objects being replaced will not require any changes.

On the other hand, the ability of objects to appear as a "black box" allows you to pack into them and represent as objects already existing applications without changing anything in them.

Using an object-oriented approach is especially effective when creating actively developing software, for example, when developing applications designed to run on different hardware platforms.

Fully object-oriented operating systems are very attractive to system programmers because, using system-level objects, programmers will be able to delve deep into operating systems to adapt them to their needs without violating the integrity of the system.

But this approach has especially great prospects in the implementation of distributed computing environments. While currently the different packages currently running on the network are statically linked sets of programs, in the future, using an object-oriented approach, they can turn into a single set of dynamically linked objects, where each object quickly sets and breaks communication with other objects to perform tasks that are relevant at the moment. Applications built for such an object-based network environment can run by accessing multiple objects dynamically, regardless of their location on the network and regardless of their operating environment.

Since any object-oriented application is a set of objects, it is desirable for a developer to have standard tools for managing objects and organizing their interaction. When using and developing object-oriented applications in heterogeneous distributed environments, you also need tools that simplify access to network objects. When a request is made to any object in a distributed environment, regardless of whether the required object is located on the same computer or on one of the remote ones, the object must be searched transparently, a message is sent to it, and a response is returned. To ensure transparent discovery of objects, all of them must be provided with links stored in directories. Hence the very difficult problem of organizing a directory service that allows programmers to name and search for objects in a network that, in general, can be scattered all over the world.

However, despite the mentioned difficulties and problems, the object-oriented approach is one of the most promising trends in software design.

OLE Tools

For Windows users object-oriented approach manifests itself when working with programs that use Microsoft's OLE technology. In the first version of OLE, which debuted in Windows 3.1, users could insert objects into client documents. Such objects established a link to data (in the case of binding) or contained data (in the case of embedding) in a format recognized by the server program. To launch the server program, users double-clicked on an object, whereby they passed the data to the server for editing. OLE 2.0, currently available as a Windows 3.1 extension, redefines the client document as a container. When the user double-clicks on an OLE 2.0 object inserted in a container document, it is activated in the same location. Imagine, for example, that the container is Microsoft document Word 6.0, and the inserted object is a set of cells in Excel 5.0 format. When you double-click on a spreadsheet object, Word menus and controls magically change to Excel menus. As a result, as long as the spreadsheet object has focus, the word processor becomes a spreadsheet.

The infrastructure required to support such complex object interactions is so extensive that Microsoft calls OLE 2.0 "1/3 of the operating system." Object storage, for example, uses a docfile, which is really a miniature file system contained within a normal MS-DOS file. Docfile has its own internal mechanisms for subdirectory, lock, and transaction (i.e., commit-revert) semantics.

The most notable shortcoming of OLE is the lack of network support, and this will be of the highest priority in the development of future versions of OLE. The next major iteration of OLE will appear in a distributed, object version of Windows called Cairo, expected in 1995.