Information resources and Internet services. Information resources and services of computer networks

05.11.2019 Windows 7, XP

Keywords:

The World Wide Web
uniform resource locator (URL)
HTTP protocol
file archives
FTP protocol
Email
forum
teleconference
social network
login
password

The Internet attracts users with its information resources and services (services), the most demanded of which are currently:

The World Wide Web;
file archives;
Email;
collective interaction services (forum, teleconference, chat, social network).

In order to use the Internet services, you need to go through authorization on the corresponding sites, that is, enter your username and password in a special form.

Login- this is a combination of various symbols that the service associates with the user; in other words, this is the username under which it will be "seen" by other network users. Therefore, the login should not be an incoherent set of characters; it is desirable that the login is memorable, somehow associated with the user. Login must be unique. The same login can be used on different sites and services.

Password- this is a combination of various symbols confirming that it is the owner of the login who intends to use the login. The password should be known only to the user and should be such that it would be difficult for outsiders to guess it. It is advisable to adhere to the following rules when generating a password:

the password must not be the same as the login;
the password must be at least six characters long (letters, numbers, punctuation marks, etc.);
characters in the password should not form any words, numbers, abbreviations associated with the user;
the password must be simple enough for the user to remember.

6.3.1. The World Wide Web

The World Wide Web, or WWW, is a service through which network users gain access to information resources stored on computers in different parts of the world. The WWW is based on Web pages and Web sites, where information is presented in the form of hypertext and hypermedia documents.

You have already repeatedly traveled the World Wide Web using browsers, following hyperlinks; searched for answers to your questions using search engines using keywords.

Problem 1... The table lists the requests to the search server. The | symbol is used to denote the logical OR operation in queries, and the & symbol is used for the logical AND operation.

Graphically plot the number of pages that the search engine will find for each query. Arrange the request numbers in descending order of the number of pages that the search engine will find for each request.

Solution... Let's graphically depict the results of executing queries using Euler circles:

Another possibility of searching for the desired document on the Internet is using the address of the document.

A document's Internet address - its URL (Uniform Resource Locator) consists of the following parts:

protocol name with signs: // at the end of the name;
domain name of the server with / at the end of the name;
the full name of the file on the server where it is located.

Consider an example of an address (URL):

http: // fcior.edu.ru/card/701/algebraicheskie-uravneniya.html

The first part of the address is the name of the protocol. It defines the type of document. The HTTP: // entry indicates that this is a Web page (HTTP - Hyper Text Transfer Protocol). For other types of documents, the protocols may be different.

The second part of the address is the domain name of the server that stores the page.

http: // fcior.edu.ru/ card / 701 / algebraicheskie-uravneniya.html

The third part of the address is the full name of the file, including the path to the file, that is, all directories that must be sequentially entered in order to open the required file.

http://fcior.edu.ru/ card / 701 / algebraicheskie-uravneniya.html

Task 2... The ftp.net file located on the txt.org server is accessed via the http protocol. In the table, fragments of the file address are coded with letters from A to G. Write down the address of the specified file on the Internet and the sequence of letters encoding this address.

Solution... The first part of the file address is the name of the protocol:

The second part of the address is the name of the server (the computer on which the file is located):

The third part of the address is the full name of the file on the computer:

Answer: http://txt.org/ftp.net, GVZHEDBA.

6.3.2. File archives

There are many file archives on the Internet - a kind of library that stores files with software, graphics, music and other information.

User access to files in file archives is possible both via the HTTP protocol and the special file transfer protocol FTP (File Transfer Protocol). FTP allows you to connect to file archive servers, browse directory contents, and upload files from or to a server. If the transfer of a file was interrupted for any reason, the FTP protocol provides a means to resume the file, which is very convenient when transferring large files.

The file address on the file archive server includes the file access protocol, server name, and fully qualified file name. So, if the htm.exe file located on the com.edu server is accessed via the ftp protocol, then its address will be written as follows:

ftp: //com.edu/htm.exe

Many files received via FTP are compressed, that is, reduced in size. Compressed files take up less disk space and are transferred faster over the network. The names of such files usually end with the extensions zip, arj, rаr and others, depending on the type of archiving program in which they were created. After copying the compressed file, it should be unpacked, i.e. restore its original form.

6.3.3. Email

Electronic mail (e-mail) is a system for the exchange of messages (letters) between subscribers of computer networks. It has several advantages over regular mail, namely:

high speed of message forwarding;
the ability to send, in addition to text documents, attached files containing graphics, sound, etc .;
the ability to simultaneously send letters to several recipients at once.

Currently, e-mail (postal service) is one of the main services of the Internet. Any Internet user can create his own mailbox - a named area of disk storage on the mail server of his provider, where incoming and outgoing mail will be placed. The user who registered his mailbox receives an email address that looks like:<имя_пользователя>@.

First part (<имя_пользователя>) is selected by the user himself; second part (<имя_сервера>) is rigidly linked to the server on which the user registered his mailbox. The @ symbol is used as a separator between the parts of the address.

Below is an example of an email address:

The mail server periodically scans the mailboxes of subscribers and sends outgoing correspondence over the network (Fig. 6.6).

Rice. 6.6.
How e-mail works

Unlike other Internet services, e-mail uses not one, but two protocols:

SMTP (Simple Mail Transfer Protocol) - for sending mail;
POP3 protocol (Post Office Protocol 3 - post office protocol, version 3) - for receiving mail.

Since anyone and anyone has the right to send mail, the SMTP protocol does not imply the identification of the sender. The letter should be received by the person to whom it is addressed; here identification of the recipient (by login and password) is required, which is provided by the POP3 protocol.

Users can view e-mail messages either using special programs (mail clients), or through the Web interface.

Each of these methods has its own advantages and disadvantages. The advantage of email clients is that when using them, there is no need for a permanent connection to the Internet. The Internet is needed for a short time to download messages from the mail server to the user's computer. All user correspondence (both received and sent) is stored on this computer. The disadvantage of this method is that access to the mailbox is carried out only from the computer on which the mail client configured for a specific user is installed.

When using the Web-interface, work with e-mail is carried out using a browser, into the window of which a special hypertext page of the postal service website is loaded. In this case, all the user's correspondence is stored in his mailbox on the mail service server. Access to messages is carried out from any computer connected to the network, however, in order to read the correspondence, in this case, an Internet connection is required.

Currently, the most popular email clients are Microsoft Outlook Express (included in the standard delivery of the Microsoft Windows operating system) and Mozilla Trunderbird (Fig. 6.7).

Rice. 6.7.
Logos of the most common email clients - Microsoft Outlook Express and Mozilla Trunderbird

An example of a postal service is mail.ru, the largest electronic mail system in Russia.

In our time, the service of instant exchange of small text messages in real time has become widespread. ICQ is the most well-known program used for this purpose. Each ICQ user is assigned a personal ICQ number. Unlike e-mail, in which there is a possibility of delayed message delivery, messages in ICQ are transmitted in real time.

6.3.4. Networked Collaboration

Network users have the opportunity to take part in various forms of collective interaction - teleconferences, forums, chats, social networks.

Teleconference is a system for the exchange of information on a specific topic between network users. It is not limited by time and can last for months and years. First, the opening of a conference on a specific topic is announced on the computer network. The newsgroup receives its email address. Then a subscription is made to participate in this teleconference. After that, each user who subscribes to the conference receives all its materials in his mailbox. In turn, by sending a letter to the address of the conference, the user knows that it will reach all its participants. Most conferences are regulated by moderators - the participants, whose duties include viewing messages and making decisions - whether to publish these messages (send to all conference participants) or not.

To organize communication between visitors to the Web site, Web forums are organized. The forum offers a set of discussion sections. Registered on the site users, sending their messages, can create topics within the sections and conduct discussions within these topics. The message and all the replies to it form a "thread" of the forum. Unregistered users receive the status of guests who can view forum threads, but are not allowed to participate in discussions. Compliance with the rules is monitored by moderators who have the right to edit, move and delete other people's posts in a specific section or topic.

Chat room(English chat - to chat) is a group communication service that involves the exchange of messages over a computer network in real time. A characteristic feature is real-time communication, which distinguishes chat from a forum.

Recently, among Internet users, the so-called social networks have become widespread - interactive multi-user Web sites, the content of which is filled by the network participants themselves. Such sites are automated social media that allow communication between groups of users with a common interest.

6.3.5. Netiquette

There are unspoken rules of conduct on the Internet, the so-called netiquette. Briefly, the essence of netiquette can be expressed in one phrase: "Respect your invisible partners on the Web!"

Here are the basic rules of netiquette, which it is advisable to adhere to in mail correspondence, as well as when using other services of the Internet.

Identify yourself clearly.
Know and respect your addressee.
Please include the subject of your message.
Write correctly, concisely; Let's give a clear answer to the question posed.
In text messages, you can express emotions using small pictures called emoticons.
Do not ask for confirmation of receipt of a message unnecessarily.
Avoid spam - meaningless, intrusive or rude messages addressed to another person or group of people.
Do not rely on complete confidentiality of your correspondence.

The most important thing

A document posted on the Internet has an address - URL. User access to documents posted on Web sites is possible via the HTTP protocol.

File archive - storage on the Internet of files with software, graphics, music and other information. Access to file archives is possible via the FTP file transfer protocol.

Electronic mail (e-mail) is a system of exchange of messages (letters) between subscribers of computer networks.

The main forms of collective interaction are teleconferences, forums, chats, social networks.

Login is a combination of characters associated with the user. Password - a combination of characters confirming that it is the owner of the login who intends to use the login.

Questions and tasks

Information resources of the Internet

The World Wide Web

The global Internet attracts users with its information resources and services (services), which are regularly used by about a billion people in all countries of the world.

The rapid development of the Internet, which has been taking place over the past 15 years, is primarily due to the emergence of the World Wide Web. The World Wide Web is a loose translation of the English phrase "World Wide Web", often referred to as WWW or Web.

World Wide Web Technology. The World Wide Web uses hypertext technology, in which documents are linked using hyperlinks.

As link pointers Web pages can use text fragments that are highlighted with color and underlining, as well as graphics that are highlighted with a frame. Activating the link pointer on the original Web page (for example, clicking with the mouse) leads to a transition to the desired Web page (Figure 6.10).

The World Wide Web are hundreds of millions of Internet Web servers containing hundreds of billions of Web pages that use hypertext technology.

The web page can be multimedia, that is, it can contain various multimedia objects: graphics, animation, sound and video.

The web page can be interactive, that is, contain forms with fields that are used when registering users of free e-mail, when shopping in online stores, etc.

Thematically related Web pages are usually in the form Website, that is, an integral system of documents linked together into a single whole with the help of links.

Web page address. Currently, the Internet's Web servers host an enormous number of Web pages. You can find a Web page on the Internet by using a Web page address.

Web page address includes a method of accessing the document and the name of the Internet server that hosts the document.

The Hyper Text Transfer Protocol (HTTP) is used to access Web pages. When recording a protocol, its name is followed by a colon and two slashes: http: //

As an example, let's write down the address of the title page of the Computer Science and Information Technology Web site. The page is located on the server iit.metodist.ru, therefore, the address takes the form:

http://iit.metodist.ru

Browsers. Browsing web pages is carried out using special viewers - browsers. Currently, the most common browsers are Internet Explorer, Mozilla, and Opera.

The browser window (Fig. 6.11) contains the standard elements of the application window:
- window menu containing sets of commands File, Edit, View, Favorites, Service and reference;
- a toolbar, the buttons of which allow you to switch from one Web page to another (buttons Forward, Back, Home), as well as manage the process of their loading (buttons Stop, Refresh);
- text field Address:, into which the Internet address of the desired Web page is entered from the keyboard or selected from the list;
- the work area in which web pages are viewed.

Rice. 6.11. Internet Explorer, Mozilla and Opera browsers

Virtual travel on the World Wide Web. If the computer is connected to the Internet, then you can launch one of the browsers and go on a virtual trip on the World Wide Web. The browser will automatically load the initial Web page (the address of the Web page from which the journey begins can be changed using your browser settings).

When a Web page is opened in a browser on a user's computer, it travels a long way from a remote Internet server through communication channels through several intermediate Internet servers. The speed of loading a Web page depends not on the distance to the Web server, but on the number of intermediate servers and the quality of the communication lines through which information is transmitted from server to server. There may be a situation where a Web page loads much faster from a server on a different continent than from a server on a nearby street.

To go to another web page in the text box Address: you must enter its Internet address. Many Web pages contain hyperlinks to other Web pages, so further travel on the World Wide Web can be continued by activating one of them.

In the process of reading a book (textbook, reference book, encyclopedia), it is often required to return to the material read. For a faster search for the desired page, so-called "bookmarks" are often inserted into the book. In the process of surfing the World Wide Web, it is advisable to save the Internet addresses of interesting Web pages as "bookmarks" in the browser. To visit such a page, it will be enough to activate one of the "bookmarks".

Control questions

1. What is the function of hyperlinks in the technology of the World Wide Web?

2. What parts does a web page address consist of?

6.5. Short answer assignment. Record the address of the Web page stored on an Internet server registered in the first-level domain ru, the second-level domain schools, and which has its own name www.

Email

Electronic mail (e-mail) is the most common service on the Internet. It is historically the first information service of computer networks and does not require the obligatory availability of high-speed and high-quality communication lines.

Email has several significant advantages over regular mail. The most important of these is the speed at which messages are sent. If a letter by regular mail can go to the addressee for days and weeks, then a letter sent by e-mail reduces the transmission time to several tens of seconds or, in the worst case, to several hours.

Another advantage is that an email can contain not only a text message, but also attachments (programs, graphics, sound, etc.). In addition, e-mail allows you to send a message to several subscribers at once, forward letters to other addresses, etc.

E-mail address. In order for an e-mail to reach the addressee, in addition to the message itself, it must contain the e-mail address of the recipient of the letter.

The first part of the usename mail address has an arbitrary character and is set by the user himself when registering a mailbox. The second part server.ru is the name of the Internet mail server on which the user has registered his mailbox.

E-mail address is written in a specific form and consists of two parts, separated by the @ symbol: [email protected]

The e-mail address is written only in Latin letters and should not contain spaces. For example, if the mail server has the name metodist.ru, then the names of users' mailboxes will look like:

[email protected]

E-mail addresses are stored on the user's computer in the Address Book database. The address book contains the subscriber's name, e-mail address, phone number and other data (Fig. 6.12).

Rice. 6.12. Database "Address Book"

Functioning of e-mail. An Internet user can register a mailbox on the provider's mail server, in which transmitted and received emails will be accumulated.

The mail program is used to create a mail message on the local computer. At this stage, in addition to writing the text of the message, you must specify the address of the recipient of the message (you can take it from the "Address Book"), the subject of the message and attach files to the message, if necessary.

The message transfer process begins by connecting to the Internet and delivering the message to your mailbox on a remote mail server. The mail server will immediately send this message through the Internet mail server system to the recipient's mail server in their mailbox.

To receive a letter, the addressee must connect to the Internet and deliver mail from his mailbox on a remote mail server to his local computer (Fig. 6.13).

Mail programs usually provide the user with numerous additional services for working with mail (choosing addresses from the address book, automatically sending messages to specified addresses, etc.).

Outlook Express mail program. To work with e-mail, special mail programs are required. The mail program Outlook Express, which is included in the Windows operating system, is very popular. After launching Outlook Express, the application window appears, which consists of four parts (Fig. 6.14).

Rice. 6.14. Outlook Express window

In the upper left part of the window there is a list of folders in which emails are stored:
- Inbox- contains received letters;
- Outbox- contains letters sent from the moment of creation to the moment of delivery from the user's local computer to the provider's mail server;
- Sent- contains all letters delivered to the mail server;
- Deleted- contains deleted messages;
- Drafts- contains letter templates.

The user can create their own folders for storing thematically grouped emails.

The list of contacts is located in the lower left part of the window, which provides access to information stored in the Address Book database (e-mail addresses, phone numbers, etc.).

The right window is divided into two parts. At the top, a list of messages stored in the selected folder is displayed.

The content of the selected message is displayed at the bottom of the right window.

Web-based e-mail. Some mail servers provide users with the ability to work with e-mail using a Web interface. Work with Web-mail can be done using any browser. An essential feature of Web mail is that all messages are permanently stored on the remote mail server, and not on the user's local computer.

Many Web mail servers offer anyone who wants to register a free mailbox. Registered users must enter their login and password, after which they can enter the mail system. For new users, the registration procedure is offered (Fig. 6.15).

Rice. 6.15. Login to Webmail

Control questions

1. What are the advantages of email over regular mail?

2. What are the parts of an email address?

3. How does email work?

Self-study assignments

6.6. Short answer assignment. Write down the e-mail address registered by the user fio on the zmail.ru mail server.

File archives

File archive servers. Tens of thousands of Internet servers are file archive servers and store hundreds of millions of files of various types (programs, device drivers, graphics and sound files, etc.). The presence of such file archive servers is very convenient for users, since many of the necessary files can be "downloaded" directly from the Internet.

File servers are supported by many software companies and manufacturers of computer hardware and peripherals. The software placed on such servers is freely distributed or shareware, and therefore, by "downloading" this or that file, the user does not violate the copyright law for the software.

File download managers. For the convenience of users, many file archive servers (freeware.ru, www.freesoft.ru, www.download.ru) have a Web interface, which allows working with them using browsers. Browsers are integrated systems for working with various Internet information resources and therefore include file download managers.

However, it is more convenient to use specialized file download managers for working with file archives, which allow you to continue downloading the file after the connection to the server is broken. File download managers provide the user with detailed information in numerical and graphical form about the file download process (file size, volume of the downloaded part, including percentage, download speed, elapsed and remaining download time, etc.).

Some file download managers achieve an increase in download speed by splitting the file into parts and downloading all the parts at the same time. For example, in the FlashGet file download manager, the download process for each part of a file is displayed graphically at the bottom of the application window (Figure 6.16).

File address on the file archive server. Access to files on file archive servers is possible both via the HTTP protocol and the special file transfer protocol FTP (File Transfer Protocol). The FTP protocol allows not only uploading files from remote file archive servers to a local computer, but also vice versa, transferring files from a local computer to a remote server.

File address includes the method of accessing the file and the name of the Internet server that hosts the file.

If the FTP file transfer protocol is used as a way to access the file.exe stored on the ftp.metodist.ru server, the file address will be written as follows:

ftp://ftp.metodist.ru/file.exe

Control questions

1. What files are usually stored on file archive servers?

2. What are the parts of the file address on the file archive server?

Self-study assignments

6.7. Short answer assignment. Make a note of the address of the program.exe file stored on a computer registered in the first-level domain w, the second-level domain schools and which has its own name ftp.

Chatting in Internet

Recently, communication on the Internet in real time has become more and more widespread. Increased data transfer rates and increased computer performance enable users to not only exchange real-time text messages, but also make audio and video communications.

Real-time communication servers. There are thousands of servers on the Internet that provide real-time communication. Any user can connect to such a server and start communicating with one of the visitors to this server or participate in a group meeting.

The simplest way to communicate "talk", or chat(English chat) is an exchange of messages typed from the keyboard. You enter a message using the keyboard, and it is displayed in a window that all meeting participants can see at the same time.

If your computer, as well as the computers of the interlocutors, are equipped with a sound card, microphone and headphones or speakers, then you can exchange audio messages. However, a "live" conversation is possible simultaneously only between two interlocutors.

In order for you to be able to see each other, that is, exchange video images, Web cameras must be connected to the computers.

Interactive communication using the ICQ system. In recent years, interactive communication through ICQ servers has become very popular (this three-letter abbreviation is formed from the consonance of the words "I seek you").

The ICQ interactive communication system integrates various forms of communication: e-mail, text messaging (chat), Internet telephony, file transfer, searching the network for people, etc. (Fig. 6.17).

Rice. 6.17. ICQ interactive communication program

Currently, the ICQ system has nearly 200 million registered users, with each user having a unique identification number. After connecting to the Internet, the user can start communicating with any user registered in the ICQ system and currently connected to the Internet.

Internet telephony. Internet telephony is used for the transmission of voice data over the Internet computer network. Providers of Internet telephony use special equipment to connect the Internet computer network and the regular telephone network. The user can use Internet telephony services and call directly from a computer (see Fig. 6.18) or from a regular phone, having previously dialed the number of the Internet telephony provider.

It is beneficial to use Internet telephony for calls to remote settlements and countries of the world, since a minute of such communication is much cheaper than the tariffs for long-distance and international telephone communication.

Control questions

1. What forms of real-time communication exist on the Internet?

Mobile Internet

Mobile telephone network. At present, the mobile telephone network has covered almost the entire world, and the number of mobile phone users is approaching one billion people. The exchange of information between mobile phones is carried out using a network consisting of antennas of cellular stations, interconnected by information transmission channels.

The mobile network allows you to transfer not only voice messages, but also data. Using mobile phones, you can exchange short text messages SMS as well as multimedia messaging MMS that allow you to send ringing tones for phones and graphics (for example, photos taken with the camera built into your phone).

Data exchange between the mobile telephone network and the computer network of the Internet. The mobile telephone network and the Internet computer network allow the transmission of data and voice messages, and therefore it is advisable to combine their information resources. Mobile phone operators and Internet providers provide the ability to transfer data between these networks (Figure 6.18).

Data exchange between networks allows, for example, to transfer e-mail messages from a mobile phone to an Internet mailbox, and from a computer connected to the Internet, send SMS messages to a mobile phone.

Internet access using a mobile phone. Many models of mobile phones have a built-in modem, so for wireless Internet access, you just need to connect your mobile phone to your computer and call your provider. Once your computer is connected to the Internet, you can “surf” the World Wide Web, work with e-mail, “download” files and use any other Internet resources, just like a normal cable connection. The disadvantage of such a connection is the low data transfer rate (no more than 9.6 Kbps) and the high cost per minute of the connection.

Full high-speed Internet access from a mobile phone can be carried out using the technology GPRS, at which the maximum possible data transfer rate is 170 Kbps (this is approximately 3 times faster than dial-up access). It is important that this technology provides immediate access to the Internet, without the need to dial up to an Internet provider and allows simultaneous conversation on a mobile phone and data exchange between the computer and the Internet.

You can connect a mobile phone to a computer in different ways: using a cable to the COM port, using a cable to a USB port, or wirelessly to an infrared port (Fig. 6.19).

To access information resources of the Internet directly from mobile phones, you can use WAP-browsers... WAP sites are specially adapted for the capabilities of a mobile phone (two-color graphics, small screen and small memory) and contain news, weather forecast, exchange rates, etc. From WAP sites, you can send an e-mail message or take part in a WAP chat.

Control questions

1. What is the difference between Internet telephony and mobile Internet?

2. What data can be transferred from the mobile telephone network to the computer network Internet? From the Internet to a mobile network?

Sound and video on the Internet

Sound and video files have a large information volume. To transfer such files over computer networks in standard digital formats, high-bandwidth communication lines are required. High quality digital stereo sound with a sampling rate of 48,000 times per second and a coding depth of 16 bits requires a bit rate equal to:

16 bits × 48,000 s -1 = 1,536,000 bits / s = 1,500 kbps "1.5 Mbps.

Digital video of the television standard requires a data transmission rate of about 240 Mbps for image transmission.

To reduce the volume of audio and video files without visible loss of quality, special methods of file compression are used, based on the removal of audio or video information that is not perceived by humans.

Streaming audio and video. Technologies for the transmission of streaming audio and video have become widespread on the Internet. These technologies transfer audio and video files in chunks to the local computer buffer, allowing them to be streamed even when using a dial-up connection. Reducing the bit rate on a channel can lead to temporary dropouts in audio or skipping video frames.

To listen to streaming audio and watch streaming video, multimedia players (Windows Media Player, WinAmp, etc.) are used. During playback of a streaming media file, the user receives information about the bit rate and can adjust the playback quality.

There are quite a few radio and television stations broadcasting over the Internet. Widely popular are Web cameras installed in various parts of the world (on city streets, in museums, in nature reserves, etc.) and continuously transmitting images (Fig. 6.20).

Control questions

1.Why is it necessary to compress audio and video files when transferring over the Internet?

World Wide Web The World Wide Web (WWW) is a service for accessing network users to information resources stored on computers in different parts of the world. The backbone of the WWW is Web pages and Web sites. Task 1. The table shows the requests to the search server. The | symbol is used to denote the logical OR operation in queries, and the & symbol is used for the logical AND operation. 1France | Spain | History 2France & Map & History 3France | History 4France & History Show graphically the number of pages that the search engine will find for each query. Arrange the request numbers in descending order of the number of pages.

Answer:) 2) 3) 4) France Spain History France History France History Map Solving problem 1France | Spain | History 2France & Map & History 3France | History 4France & History

Document address on the Internet - its URL (Uniform Resource Locator) consists of the following parts: Server domain name with a / at the end of the name Full name of the file on the server where it is located Protocol name with signs: // at the end of the name Consider example address (URL): fcior.edu.ru/card / 701 / algebraicheskie-uravneniya.html The entry indicates that this is a Web page (HTTP - Hyper Text Transfer Protocol). Domain name of the server where the page is stored. The fully qualified file name, including the path to the file, that is, all directories that must be sequentially navigated to open the required file. Document address on the Internet

А.net Bftp В: // Гhttp Д / Е.org Жtxt Solution. The first part of the file address is the name of the protocol: ГВ txt.org SAME / ftp DB.net А The second part of the address is the name of the server (the computer on which the file is located): The third part of the address is the full name of the file on the computer: Solving the problem Task 2. Access to the ftp.net file located on the txt.org server is carried out via the http protocol. In the table, fragments of the file address are coded with letters from A to G. Write down the address of the specified file on the Internet and the sequence of letters encoding this address. Answer: GVZHEDBA.

File archives FTP authorization General scheme of FTP work Transferring data in active mode Transferring data to a server Transferring data between two FTP servers File archives are a kind of library storing files with software, graphics, music and other information. Access to files in file archives is possible using the following protocols: HTTP - protocol for transferring hypertext documents; FTP is a special file transfer protocol.

File archives ftp: // com.edu/ htm.exe ProtocolServerFile The file address on the file archive server includes the file access protocol, server name, and full file name. Many files received via FTP are compressed. Their names end with the extensions zip, arj, rar, etc. After copying a compressed file, it should be unpacked, that is, restore its original form.

E-mail E-mail () is a system for exchanging messages (letters) between subscribers of computer networks. High speed of message forwarding Ability to forward attached files containing graphics, sound Ability to simultaneously send letters to several recipients at once Benefits of e-mail Any Internet user can create his own mailbox - a named area of disk memory on the mail server of his provider, where incoming and outgoing correspondence will be placed.

@. UsernameDomainnameCountry code E-mail address The e-mail address looks like this: The first part is chosen by the user; the second part is rigidly connected with the server on which the user registered his mailbox. The separator between the parts of the address is

The sender types the message, specifies the recipient's address and sends the letter to the outgoing mail server. The outgoing mail server sends the message to the specified address. On the Internet, the letter is forwarded to the incoming mail server specified in the recipient's address. The incoming mail server places the message in the recipient's mailbox. The recipient opens his mailbox and gains access to the letters received to him The scheme of e-mail

Mail Protocols E-mail uses two protocols: SMTP - to send mail; POP3 protocol - for receiving mail. Since anyone and anyone has the right to send mail, the SMTP protocol does not imply the identification of the sender. The letter should be received by the person to whom it is addressed; here identification of the recipient (by login and password) is required, which is provided by the POP3 protocol. Mail Server User 1 User 2 SMTP SMTP POP

Viewing messages Method Advantages Disadvantages Mail client Internet connection while downloading messages Access to the mailbox only from a computer with the mail client installed Web interface Access to mailbox from any computer To read correspondence, you need a network connection Ways to view messages

Networked collective interaction Forms of collective interaction Teleconference Forum Chat Social network A system of information exchange between network users. Unlimited in time Offers a set of discussion chapters. Real-time group communication service Interactive multi-user websites

Netiquette There are unspoken rules of conduct on the Internet, the so-called netiquette. Briefly, the essence of netiquette can be expressed in one phrase: "Respect your invisible partners on the Web!" Basic rules of netiquette Clearly identify yourself Know and respect your recipient Indicate the subject of the message Write competently You can express emotions using emoticons Do not ask for confirmation of receipt of a message unnecessarily Avoid spam Do not rely on complete confidentiality of correspondence

Most importantly, a document posted on the Internet has an address - a URL. User access to documents posted on Web sites is possible via the HTTP protocol. File archive - storage on the Internet of files with software, graphics, music and other information. Access to file archives is possible via the FTP file transfer protocol. E-mail () is a system for exchanging messages (letters) between subscribers of computer networks. The main forms of collective interaction are teleconferences, forums, chats, social networks.

Questions and Tasks Describe the organization and purpose of the service is a browser? Give examples of browsers. What documents are called hypertext documents? The table shows the queries to the search engine: 1Bulldog & Collie & Grooming 2Bulldog & Collie 3Collie 4Collie | leaving Graph graphically the number of pages that the search engine will find for each query. Arrange the request numbers in descending order of the number of pages that the search engine will find for each request. What is a URL? What is its structure? Analyze the addresses of the following documents: 1) september.ru/2007/11/01.htm 2) 3) On the edu.ru server there is a file demo.rar, which can be accessed via the ftp protocol. Fragments of the address of this file are encoded with letters from A to G. Write down the sequence of these letters, which encodes the address of the specified file on the Internet. А.rar Bdemo В: // Г / Дftp Е.edu Ж.ru What protocols are used for user access to information stored in file archives? What are the main advantages of email over regular mail? What is the structure of an email address? Describe in general terms how email works. Imagine that you need to connect with a stranger or very busy person. You were able to get this person's mobile phone number and email address. What kind of communication, in your opinion, is more convenient to use in this situation? Justify your answer. What are the ways to work with e-mail messages? Analyze the merits and demerits of each. What are the similarities and differences between forms of online collaboration such as teleconference, forum, and chat? What do you know about social media What is login? Can I use the same login on different sites? What is a password? What rules should be followed when choosing a password? Why is it not recommended to use the same password on different sites? What is the basic rule of netiquette and what is spam? Learn the history of this term.

The World Wide Web (WWW) is a service for accessing network users to information resources stored on computers in different parts of the world. The backbone of the WWW is Web pages and Web sites. Supporting Synopsis The File Transfer Protocol FTP provides access to file archives containing software, graphics, music and other information. Exchange of messages (letters) between subscribers of computer networks is carried out by e-mail (e-mail). Teleconferences, forums, chats, social networks are the main forms of collective interaction on the Internet.

Sources of information 1. 7a75fef34e81 / ftp3.swf - FTP authorization - connections 7a75fef34e81 / ftp3.swf 2.c3cdcc5ba1a1 / ftp1.swf - General FTP operation scheme http://files.school-collection.edu.ru/dlrstore/fb31e305-aee0 430e c3cdcc5ba1a1 / ftp1.swf 3.d8ba87868f1d / ftp4.swf - data transfer in active mode d8ba87868f1d / ftp4.swf bff6f / ftp5.swf - data transfer in passive mode bff6f / ftp5.swf c8f8dc74 / ftp5.swf c8f9dc74 / ftp5.swf c8f9dc74 / ftp5.swf server 5649c8f9dc74 / ftp8.swf c362d3a / ftp2.swf data transfer session between two FTP servers c362d3a / ftp2.swf 7.a348f7100c4e / ftp4.swf - data transfer in active mode a348f7100c4e / ftp4.swf / ba2361.f passive mode 538ba2361f41 / ftp5.swf netiquette eaf.jpg - email logo 7eaf.jpg 11.if - Microsoft-Outlook-Express logo http: // if

Sources of information Mozilla Trunderbird logo http://warezatut.net/uploads/posts/ / jpeg 13. ze = article_large mail.ru logo http:// ze = article_large 14.avait.jpg - ICQ logo http://images.lpcdn.ca/ 924x615 / 201106/02 / avant-reseaux-sociaux-y- avait.jpg envelope server computer network server

World Wide Web The World Wide Web (WWW) is a service for accessing network users to information resources stored on computers in different parts of the world. The backbone of the WWW is Web pages and Web sites. The presentation of information on the WWW is based on the capabilities of hypertext links. Hypertext is text that contains links to other documents. This allows you to quickly and easily move from one document to another. Linked documents can be scattered across the globe.

@. User name Domain name Country code E-mail address The e-mail address is as follows: The first part is chosen by the user himself; the second part is rigidly connected with the server on which the user registered his mailbox. The separator between the parts of the address is

Questions and Tasks Describe the organization and purpose of the service is a browser? Give examples of browsers. What documents are called hypertext documents? The table shows the queries to the search engine: 1 Bulldog & Collie & Grooming 2 Bulldog & Collie 3 Collie 4 Collie | leaving Graph graphically the number of pages that the search engine will find for each query. Arrange the request numbers in descending order of the number of pages that the search engine will find for each request. What is a URL? What is its structure? Analyze the addresses of the following documents: 1) september.ru/2007/11/01. htm 2) html 3) html The edu.ru server contains the demo.rar file, which can be accessed via the ftp protocol. Fragments of the address of this file are encoded with letters from A to G. Write down the sequence of these letters, which encodes the address of the specified file on the Internet. А.rar Bdemo В: // Г / Дftp Е.edu Ж.ru What protocols are used for user access to information stored in file archives? What are the main advantages of email over regular mail? What is the structure of an email address? Describe in general terms how email works. Imagine that you need to connect with a stranger or very busy person. You were able to get this person's mobile phone number and email address. What kind of communication, in your opinion, is more convenient to use in this situation? Justify your answer. What are the ways to work with e-mail messages? Analyze the merits and demerits of each. What are the similarities and differences between forms of online collaboration such as teleconference, forum, and chat? What do you know about social media What is login? Can I use the same login on different sites? What is a password? What rules should be followed when choosing a password? Why is it not recommended to use the same password on different sites? What is the basic rule of netiquette and what is spam? Learn the history of this term.

4.7. Information resources of the Internet.

A person who has gained access to the Internet finds himself in a world of practically unlimited information resources. It should be borne in mind that some resources may be paid. Below is a very brief overview of the main network resources.

1) Email.

Electronic mail, or e-mail (from electronic mail - electronic mail), is one of the ways of communication between people. It combines all the virtues of mail, teleprinter, telegraph and fax. Moreover, sending by e-mail is cheaper than the services of each of the considered communication means.

Example email address [email protected]

In the example under consideration, sas is the subscriber's identifier, usually made up of the initial letters of his last name, first name, and patronymic. The one to the right of the @ sign is called a domain and uniquely describes the location of the subscriber [email protected]- a required character in the e-mail address.

2) World Wide Web.

Probably the most interesting, convenient and effective resource that is currently very popular is hypertext network information systemWorldWideWeb(The World Wide Web). The World Wide Web, which for short is called the Web or WWW, is a hypertext (more precisely, hypermedia) information system containing documents linked by links that can be created in various software environments and located on any computer on the Internet.

Hypertext can be considered as text containing links that are associated with the definition, explanation, additions of individual words, phrases, images included in the text under consideration. The most important property of hypertext is automatic access to information associated with the link specified by the user. The search for this information and its display on the screen is carried out using special programs for working with hypertext.

3) Resource address.

From the point of view of the operating system, each web page is a file located on one of the disk devices of the computer playing the role of a web server. Therefore, in order to access a web page, you need to point in one way or another to the file that stores this page.

http://sunsite.unc.edu/boutell/fag/www_fag.html

http - protocol

sunsite.unc.edu - computer domain address

boutell / fag / www_fag.html - file

4) Electronic bulletin boards.

On electronic bulletin boards (in the literature, the abbreviation BBS is often used for Bulletin Board System - bulletin board system) advertisements are posted that are sent by users to everyone who reads them. Electronic boards are analogous to regular bulletin boards, which are posted in public, frequently visited places. You can also draw an analogy with advertisements in newspapers and magazines.

5) Teleconferences.

On the basis of e-mail programs, electronic bulletin boards and other special packages, business meetings, scientific conferences are held, in which several people can participate at their workplaces in different cities or countries.

6) File transfer.

Messages sent over the network can only be ASCII codes. However, by attaching any file to a message, it can also be sent over the network, but only in offline mode. There is another way on the Internet to transfer arbitrary files between computers. This method is based on the protocol FTP(File transfer Protocol), which involves the transfer of files in the so-called operational, or online, mode. This means that for the duration of the file transfer, the sending and receiving computers must be in direct contact with each other (like people talking to each other on the phone).

7) Remote access.

The FTP protocol is quite powerful, but at the same time a limited means of accessing the resources of "foreign" computers on the network. It provides only copying, that is, transferring copies of files from one computer on the network to another. Full access to the resources of computers on the Internet is provided by the protocol telnet(TErminaL over NETwork protocol - remote access protocol). Using this protocol, a user can connect to a computer on the opposite side of the globe and work with it as if it were a personal computer.

8) Search for servers.

As noted above, in order to use ftp or telnet protocols, you need to know the domain address of the corresponding server. If such an address is unknown, then access to the required resource can be significantly hampered. To make it easier to find the right servers on the Internet, a menu-based system for accessing Internet servers has been developed. This system was named GOPHER... The term comes either from the word gopher - a gopher (Minnesota, the birthplace of this system, is considered the state of "golden gophers"), or from the slang term go fer - a prowling man.

9) Databases on the Internet.

A large number of databases are connected to the Internet, containing a huge amount of information on a variety of issues: from information on specific sciences - biology, mathematics, physics - to a collection of anecdotes and fables. As a rule, they are part of a public information system. WAIS(Wide Area Information System). A computer that has special software and provides users with access to the databases of this system is called wais-server.

WAIS connects wais servers around the world with access to over 1000 public and commercial databases. To access WAIS, you need to know the home address of a particular wais server.

Information resources and Internet services. Information resources and services of computer networks

6.3.1. The World Wide Web

6.3.2. File archives

6.3.3. Email

6.3.4. Networked Collaboration

6.3.5. Netiquette

The most important thing

Questions and tasks

Information resources of the Internet

The World Wide Web

Email

File archives

Chatting in Internet

Mobile Internet

Sound and video on the Internet

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