Ways to work with email. Possibilities of using information transmission media
Email- a means of exchanging information prepared in electronic form between people with access to a computer network.
The main applications of e-mail are personal correspondence and work with certain Internet information resources, such as mailing lists, off-line news groups and e-mail file transfer systems.
Mail server - a program that forwards messages from mailboxes to other servers or to the user’s computer at the request of his mail client.
Mailboxes are created on the mail server for users with a specific username and password for access. The client part of the service is represented by an email client.
Mail client (mailer)- a program that helps you compose and send emails, receive and display letters on the user's computer.
Work with mail can be carried out off-line. This means that in order to receive and send mail at the appointed time, you establish a connection with the provider. Then you give a command to your mail client, by which it connects to your mail server, sends prepared letters and collects messages that have arrived in your mailbox over the past period on your local computer. You can write letters and read messages received from the server in offline mode, that is, without an Internet connection.
Thus, email allows you to freely exchange electronic messages even when the sender and recipient are not online at the same time.
Email(e-mail – electronic mail) is one of the earliest information services Internet. It allows you to transmit letters containing text or files in binary code (graphics, sound, programs) through computer networks.
The postal service is based on two application protocols: SMTP And POP3 . By SMTP correspondence is sent from the computer to the server, and POP3 - receiving incoming messages.
Providing e-mail special mail servers handle this. Mail servers receive messages from clients and forward them along the chain to the recipients' mail servers, where these messages are accumulated. When a connection is established between the recipient and his mail server, incoming messages are automatically transferred to the recipient's computer.
There is a wide variety of client email programs. For example, Microsoft Outlook Express , included in the operating system Windows;The Bat!;Eudora Pro etc. These programs perform the following functions: text preparation; reading, saving and deleting correspondence; entering an address; commenting and forwarding correspondence; import (reception and conversion to the desired format) of other files.
IN Internet There are also many free email services. For example:Hotmail( http :// www . hotmail . com );AltaVista( http :// altavista . digital . com );Usa.net( http :// www . USA . net );Mail.ru( http :// www . mail . ru ), and etc.
The difference between these services and mail received through a provider using a mail program is that working with a free mailbox occurs using a browser. The universal qualities of such mail are its accessibility from anywhere, from any computer with access to Internet which has a browser and a fairly high level of anonymity.
The email address consists of [email protected]
Today, courts often accept electronic correspondence as written evidence. However, for this she must have legal force. Meanwhile, clear and uniform rules and methods for determining the legitimacy of virtual correspondence have not yet been developed, which leads to a large number of problems.
Let's look at several ways to give emails legal force.
Long gone are the days when the only means of communication were letters written on paper. The development of economic relations between economic entities is no longer conceivable without the use of information technology. This is especially true when counterparties are located in different cities or even countries.
Communication via electronic communications helps reduce material costs, and also allows as soon as possible develop a common position on specific issues.
However, such progress should not be considered only in terms of positive side. Various disputes often arise between subjects of economic relations; to resolve them, they turn to the courts. The court makes a decision based on an assessment of the evidence provided by the parties.
At the same time, the relevance, admissibility, reliability of each evidence separately, as well as the sufficiency and interconnection of the evidence in their totality are analyzed. This rule enshrined both in the Arbitration Procedure Code of the Russian Federation (clause 2 of Article 71) and in the Code of Civil Procedure of the Russian Federation (clause 3 of Article 67). In the process of determining the admissibility and reliability of the evidence provided, the court often asks questions, the solution of which significantly affects the outcome of the case.
Usage electronic document management in relations between economic entities is regulated by the norms of the Civil Code of the Russian Federation. In particular, in paragraph 2 of Art. 434 states: an agreement in writing can be concluded by exchanging documents via electronic communication, which makes it possible to reliably establish that the document comes from a party to the agreement.
In accordance with paragraph 1 of Art. 71 Code of Civil Procedure of the Russian Federation and paragraph 1 of Art. 75 of the Arbitration Procedure Code of the Russian Federation, written evidence is business correspondence containing information about circumstances relevant for the consideration and resolution of the case, executed in the form digital recording and received via electronic communication.
To use electronic documents in legal proceedings, two conditions must be met. Firstly, as already indicated, they must have legal force. Secondly, the document must be readable, that is, it must contain information that is generally understandable and accessible to perception.
This requirement follows from the general rules of legal proceedings, which presuppose the immediacy of judges’ perception of information from sources of evidence.
Often the court refuses to include it as evidence in the case materials. email correspondence, which does not meet the above conditions, and subsequently makes a decision that does not satisfy the legitimate requirements of the interested party.
Let's consider the main ways to legitimize electronic correspondence before and after the start of proceedings.
Working with a notary
If the proceedings have not yet begun, then to give electronic correspondence legal force, you need to involve a notary. In paragraph 1 of Art. 102 of the Fundamentals of Legislation on Notaries (Fundamentals) states that, at the request of interested parties, a notary provides evidence necessary in court or an administrative body if there are reasons to believe that the provision of evidence will subsequently become impossible or difficult. And in paragraph 1 of Art. 103 of the Fundamentals stipulates that in order to secure evidence, the notary inspects written and material evidence.
According to paragraph 2 of Art. 102 Fundamentally, a notary does not provide evidence in a case that, at the time interested parties contact him, is being processed by a court or administrative body. Otherwise, the courts recognize notarized electronic correspondence as inadmissible evidence (Resolution of the Ninth AAS dated March 11, 2010 No. 09AP-656/2010-GK).
It is worth recalling that, based on Part 4 of Art. 103 Fundamentals, provision of evidence without notifying one of the parties and interested parties is carried out only in urgent cases.
In order to inspect evidence, a protocol is drawn up, which, in addition to a detailed description of the notary’s actions, must also contain information about the date and place of the inspection, the notary conducting the inspection, the interested parties participating in it, and also list the circumstances discovered during the inspection. The emails themselves are printed and filed with a protocol, which is signed by the persons participating in the inspection, by a notary and sealed with his seal. By virtue of the Determination of the Supreme Arbitration Court of the Russian Federation dated April 23, 2010 No. VAS-4481/10, the notarial protocol for the inspection of an electronic mailbox is recognized as appropriate evidence.
Currently, not all notaries provide services for certification of emails, and their cost is quite high. For example: one of the notaries in Moscow charges 2 thousand rubles for one page of the descriptive part of the protocol.
A person interested in providing evidence applies to a notary with a corresponding application. It should indicate:
- evidence to be secured;
- the circumstances that are supported by this evidence;
- the grounds for which evidence is required;
- absence of a case in court proceedings at the time of contacting a notary general jurisdiction, arbitration court or administrative body.
Notaries inspect the contents email box or remotely, that is, they use remote access to a mail server (this may be the server of a provider providing an electronic communication service under a contract; a mail server of a domain name registrar or a free Internet mail server), or directly from the computer of the interested person on which the program for working with by email(Microsoft Outlook, Netscape Messenger, etc.).
During a remote inspection, in addition to the application, the notary may need permission from the domain name registrar or Internet provider. It all depends on who exactly is supporting the work. mailboxes or electronic mail server under contract.
Certification from the provider
Resolutions of the Ninth AAS dated 04/06/2009 No. 09AP-3703/2009-AK, dated 04/27/2009 No. 09AP-5209/2009, FAS MO dated 05/13/2010 No. KG-A41/4138-10 stipulate that the courts also recognize the admissibility of electronic correspondence , if it is certified by the Internet service provider or domain name registrar who are responsible for managing the mail server.
The provider or domain name registrar certifies electronic correspondence at the request of an interested party only if it manages the mail server and such right is specified in the service agreement.
However, the volume of electronic correspondence can be quite large, which in turn can complicate the process of providing paper documents. In this regard, the court sometimes allows the provision of electronic correspondence on electronic media. Thus, the Arbitration Court of the Moscow Region, making a Decision dated August 1, 2008 in case No. A41-2326/08, referred to the admissibility of electronic correspondence provided to the court on four CDs.
But when considering the case in the appellate instance, the Tenth AAC, by its Resolution dated 10/09/2008 in case No. A41-2326/08, recognized the reference to electronic correspondence as unfounded and canceled the decision of the court of first instance, indicating that the interested party did not submit any documents provided for by the concluded parties agreement.
Thus, emails relating to the subject of the dispute must be submitted to the court in writing, and all other documents can be submitted on electronic media.
Confirming the contents of letters by referring to them in subsequent paper correspondence will help prove the facts stated in virtual correspondence. The use of other written evidence is reflected in the Resolution of the Ninth AAS dated December 20, 2010 No. 09AP-27221/2010-GK. Meanwhile, the court, when considering the case and assessing the evidence provided by the parties, has the right not to consider paper correspondence with links to electronic correspondence admissible.
He only takes it into account and makes a decision based on a comprehensive analysis of all the evidence presented.
Get help from an expert
If the proceedings have already begun, then to give electronic correspondence legal force it is necessary to exercise the right to attract an expert. In paragraph 1 of Art. 82 of the Arbitration Procedure Code of the Russian Federation stipulates that in order to clarify issues that arise during the consideration of a case that require special knowledge, the arbitration court appoints an examination at the request of a person participating in the case, or with the consent of the persons participating in it.
If the appointment of an examination is prescribed by law or a contract, or is required to verify an application for falsification of the evidence presented, or if an additional or repeated examination is necessary, the arbitration court may appoint an examination on its own initiative. The appointment of an examination for the purpose of verifying the evidence presented is also provided for in Art. 79 Code of Civil Procedure of the Russian Federation.
In the application for appointment forensics it is necessary to indicate the organization and specific experts who will carry it out, as well as the range of issues for which the interested party decided to apply to the court to order an examination. In addition, information about the cost, timing of such an examination should be provided and deposited with the court full amount to pay for it. The involved expert must meet the requirements established for him in Art. 13 of the Federal Law “On State Forensic Expert Activities in the Russian Federation”.
Attachment to the case materials as evidence of an expert's opinion on the authenticity of electronic correspondence is confirmed by judicial practice (Decision of the Moscow Arbitration Court dated 08/21/2009 in case No. A40-13210/09-110-153; Resolution of the Federal Antimonopoly Service of the Moscow Region dated 01/20/2010 No. KG-A40 /14271-09).
Based on the contract
In paragraph 3 of Art. 75 of the Arbitration Procedure Code of the Russian Federation notes that documents received via electronic communication are recognized as written evidence if this is specified in the agreement between the parties. Accordingly, it is necessary to indicate that the parties recognize the equal legal force of correspondence and documents received via fax, the Internet and other electronic means of communication as the originals. In this case, the contract must specify the email address from which electronic correspondence will be sent, and information about confidant authorized to conduct it.
The contract must stipulate that the designated email address is used by the parties not only for work correspondence, but also for the transfer of work results, which is confirmed by the position of the FAS MO in Resolution No. KG-A40/12090-08 dated January 12, 2009. The Decree of the Ninth AAS dated December 24, 2010 No. 09AP-31261/2010-GK emphasizes that the contract must stipulate the possibility of using e-mail for approval terms of reference and making claims regarding the quality of services provided and work performed.
In addition, the parties may provide in the agreement that notifications and messages sent by email are recognized by them, but must be additionally confirmed within a certain period by courier or by registered mail(Resolution of the Thirteenth AAS dated April 25, 2008 No. A56-42419/2007).
To summarize, we can say that today there is a practice of courts using electronic correspondence as written evidence. However, taking into account the requirements of procedural legislation regarding the admissibility and reliability of evidence, virtual correspondence is taken into account by the court only if it has legal force.
In this regard, there arises a large number of problems, since a unified methodology for determining the legitimacy of electronic correspondence has not yet been formed. The right of an interested party to contact a notary in order to secure evidence is enshrined, but there is no regulatory act of the Ministry of Justice of the Russian Federation regulating the procedure for the provision of such services by notaries. As a result, there is no single approach to determining their value and forming a clear mechanism for implementing this right.
There are several ways to give electronic correspondence legal force in order to present it as evidence in court: securing electronic correspondence from a notary, certification from an Internet provider, by reference to emails in further paper correspondence, as well as confirmation of their authenticity by forensic examination.
A competent approach to the timely provision of electronic correspondence as written evidence will allow business entities to fully restore their violated rights when resolving disputes.
7 TECHNOLOGY CLIENT / SERVER Mail server - a program that forwards messages from mailboxes to other servers or to the user’s computer at the request of his mail client Mail client (meller) - a program that helps compose and send electronic messages, receive and display letters on the user’s computer
9 MODERN INTERNET MAIL Internet mail protocols: SMTP (simple mail transfer protocol) is a mail protocol used for sending messages from a client computer to a mail server, as well as for sending mail between servers. Used on outgoing information servers
10 MODERN INTERNET MAIL Internet mail protocols: POP3 (Post Office Protocol) or IMAP (Message Access Protocol) - protocols for gaining access to a mailbox on a server and sending messages to a client computer. Used on incoming mail servers
12 EMAIL ADDRESS Example address:
13 “ENVELOPE” FORMAT OF AN ELECTRONIC LETTER To: (To:) - (email address is indicated) Copy: (Cc:) - (to whom else should the same letter be sent; the addressees will see each other) Hidden copy: (Bcc:) - (the recipient will not know who else you sent this letter to) Subject: (Subject:) - (the essence of the information being sent)
14 PROBLEMS AND LIMITATIONS Type transmitted information Universally (without possible losses) transmitted only text information on English language The most commonly used Cyrillic encodings: KOI8-R (for Unix OS) CP1251 (for MS Windows) CP866 (for MS DOS)
15 CODING OF EIGHT-BIT CHARACTERS AND BINARY ETTINGS Uuencode is an encoding method that allows you to reduce an eight-bit encoding to a seven-bit encoding text ASCII MIME (Multipurpose Internet Mail Extension, multipurpose email extensions) is a standard according to which a letter can contain text, pictures, video and binary data
25 STYLE AND ETIQUETTE Checking spelling and grammar Sparing use of CAPITAL LETTERS (THE ELECTRONIC EQUIVALENT OF SCREAMING!!!) Punctuation: !!!?????!! - expression of confusion - interpreted as an impartial expression
28 CREATE A FREE MAILBOX ON WWW Open home page one of the servers: Select the command to create a mailbox Sign me Up... or Receive mailing address or Registration
30 SECURITY AND ENCRYPTION To ensure security, there are special means, such as encryption and digital signature. Both of these concepts are related to cryptography Encryption makes the contents of the message incomprehensible to the uninitiated Digital signature verifies the author of the message
31 SECURITY AND ENCRYPTION Support for S/MIME (Secure Multipurpose Internet Mail Extention) standard Asymmetric encryption (personal and public key i) the public key can be sent to the recipient along with a digital signature. It is used to encrypt messages sent to you; the private key is stored on your PC and is used to decrypt messages from your recipient
34 MAILING LISTS. DEFINITION Mailing list - a special address whose mailbox processes special program- mailing list server (dispatcher) Mailing server - a thematic server that collects information on certain topics and forwards it to subscribers in the form of emails Controlled lists Uncontrolled lists
35 WORKING WITH MAILING LISTS Mailing server address Requests for help, subscription and unsubscription are sent to the mailing server address in the form of an email (Subject field is empty!)
36 WORKING WITH MAILING LISTS Mailing list address Articles for mailing are sent to the mailing list address
37 STANDARD COMMANDS FOR WORKING WITH THE NEWSLETTER SERVER help (send a list of commands for working with the mailing server) list (get addresses available lists mailings) subscribe list_name Your_name (subscribe to a specific list) signoff (for listserv) or unsubscribe (for majordomo) list_name (to unsubscribe)
38 NEWS GROUPS (TELECONFERENCES). DEFINITION Newsgroup (teleconference) - a network forum organized for discussion and exchange of news on a specific topic Usenet - a global distributed system for discussion, including many news groups stored on servers around the world NNTP - News Transfer Protocol
39 CLIENT/SERVER TECHNOLOGY News server is a program that provides access to news groups hosted on this server. Example news server address news.unibel.by Newsreader (client program for reading news) - a program that uses the NNTP protocol to transfer news group messages from the news server Examples of news clients: Outlook Express, Netscape Collabra
40 TYPES OF NEWS GROUPS Unmoderated (unmanaged) news groups - anyone can send a message there or reply to a message in this group Moderated (managed) news groups - all messages and replies are controlled by the moderator (manager) of this group, who has the right to select articles
41 NAMES OF TELECONFERENCES The name of the conference is organized hierarchically into categories and subcategories For example, fido.networks.bel-internet – news group FidoNet networks dedicated to discussion network problems(networks), in particular, Internet problems in Belarus (bel-internet)
42 MAIN FEATURES OF THE NEWS CLIENT Creation account for news server Connect to a specific news server View available groups news Receive and read articles Subscribe to and unsubscribe from a group Send an article to a group or author Work offline
44 IRC. TECHNOLOGY CLIENT/SERVER IRC servers - programs that ensure the functionality of the IRC system and store information about channels and connected users IRC system - several IRC servers connected to each other IRC client - a program for connecting to an IRC server and conducting a conversation. Client example: mIRC
46 FEATURES OF MS NETMEETING Connect to a directory server (ILS server), view the list of users registered on the server Call a specific user through a directory server or local network by IP address or join an ongoing call. Participants have equal rights
47 MS NETMEETING FEATURES Organization of a meeting at a scheduled time (the meeting is controlled by a leader with special powers) Chat with meeting participants by entering text from the keyboard Collaboration with graphics on a common Board
49 INTERNET PAGING DEFINITION Internet paging is a system that allows you to register in your server system and receive a unique paging number. Using this system you can find and call a person who has a paging number and is currently connected to the Internet
50 INTERNET PAGER ICQ. MAIN FEATURES The most popular Internet pager ICQ. A play on words I Seek You (I'm looking for you) or Registration in the ICQ server system and receiving a UIN (Universal Internet Number) Every time you connect to the Internet ICQ program determines the current IP address of your computer and sends it to the central server
51 INTERNET PAGER ICQ. MAIN FEATURES Automatic search for specified people on the ICQ network and creation of your own list of subscribers for constant communication Calling the interlocutor by his UIN and sending a message with an offer to establish contact Conversation (Chat) in real time Exchange of messages, letters and files
52 INTERNET TELEPHONY. DEFINITION Internet telephony is a system that allows you to conduct a conversation in real time, one of the links of which is the Internet IP telephony service telephone communication, in which for transmission sound signal networks using the IP protocol are used
53 EXAMPLES OF PROGRAMS IMPLEMENTING INTERNET TELEPHONY MS NetMeeting Special program for input, forwarding and playback audio information Speak Freely ( Internet program Phone (
54 INTERNET TELEPHONY. MAIN FEATURES Transmitting audio for one subscriber Coding (encryption) of a signal to ensure the confidentiality of conversations Transmitting audio for a group of subscribers and conducting an audio conference Working in answering machine mode Exiting to telephone network through special telephone gateways
55 LITERATURE Modern self-instruction manual for working on the Internet. Fast start. - M.: TRIUMPH Publishing House, p. A modern tutorial for working on the Internet. The most popular programs. - Ed. Komyagina V.B. - "TRIUMPH Publishing House" - Moscow, p. Bradley F. Shimmy. Effective use Email. "Enter" series. Rostov-on-Don: “Phoenix”, – 304 p.
56 REFERENCES Cox J., Kok T., Heidrick E. - Microsoft Internet Explorer 4: short course. - St. Petersburg: Peter, p. Bogumirsky B. - Windows 98 Encyclopedia (second edition). - St. Petersburg: Peter Kom, p. Using the Internet: Per. from English / J. Honeycutt et al. - 4th ed. - K.;M.; SPb: Publishing house. Williams House, p.
EXAMINATION TICKET No. 1
1. Physical and logical structure disk. Disk structure. Physical (low-level) disk formatting. Logical (high-level) disk formatting. Disk logical devices. File system FAT.
HDD consists of one or more metal plates, each of which is coated on one or both sides magnetic material. Thin concentric rings are marked on each side of each plate - tracks.
Track numbering starts from 0 from the outer edge to the center. As the disk spins, an element called the head reads or writes binary data.
The set of tracks of the 1st radius on all surfaces of all plates is called cylinder. Each track is divided into sectors or blocks, so that all tracks have an equal number of sectors. The sector has a fixed size – 512 bytes.
Tracks and sectors are created as a result of the procedure physical or low level formatting . The low-level disk format does not depend on the type of OS that will be installed. Disk layout under specific type file system performs the procedure high-level (logical) formatting. When working with a disk, the OS uses its own unit of disk space, called cluster.
Cluster it is a group of related sectors. The cluster size is a multiple of the power of 2.
At high level formatting a cluster size is created and the following is written to the disk: information necessary for the operation of the file system, information about damaged areas of the disk, OS loader - a program responsible for initializing the OS after turning on the power or restarting the computer. Before high-level formatting, the disk may be partitioned into sections.
Chapter– continuous part physical disk, which the OS provides to the user as a logical device.
Logical device functions as if it were a separate physical disk. The user accesses a logical device by symbolic names. Only one file system can be created on each logical device. On different logical devices file systems can be located on the same physical disk different types. On a FAT file system logical space is divided into two areas: system and data area. The system area is created during high-level formatting and consists of: 1. boot record, 2. reserved sectors, 3. allocation table FAT files. The primary sector of the logical disk contains the file system loader. The data area of a logical disk is divided into clusters and contains directories. A file or directory in length occupies an integer number of clusters; if the file occupies more than one cluster, then these clusters are organized into a chain of clusters. The location of files in a cluster is determined using a FAT table of file sizes, in which each cluster has its own element. Elements 0 and 1 are service elements, the number of the first cluster starts with 2ki. Cluster numbers correspond to table elements. FAT elements determine the position of clusters in the chain and its state. When creating and writing a file, the OS performs the following functions: 1. Creates a description of the file in a free directory element. 2. Searches for a free FAT element and places a link to it in the directory element (this is how the first cluster of the first chain is filled. 3. The number of the next occupied cluster or the sign of the last cluster in the chain is placed in this FAT element
2. Binary decryptors. Purpose. Circuit implementation. Functional description. Circuit implementation. Increasing dimension. Arbitrary playback scheme logical functions using a decoder.
Decoder – a code converter, and specifically a binary decoder – converts a binary code into code 1 from N.
A binary decoder having n inputs must have 2 n outputs corresponding to the number different combinations in n-bit binary code.
Depending on the input binary code, one and only one of the output circuits is excited at the decoder output. If some of the input sets are not used, then the decoder is called incomplete, and its number of outputs is less than 2n.
Circuit implementation:
IN symbol decryptors are marked with the letters DC. The decoder inputs are usually designated by binary weights. In addition to information inputs, the decoder usually has one or more operation enable inputs designated as EN. If there is permission on this input, the decoder operates in the manner described above; if it is absent, all decoder outputs are passive. If there are several enable inputs, then the operation enable signal is formed as a conjunction of the signals of the individual inputs. Often the decoder has inverse outputs. In this case, there is only one exit null value, and all the rest are single. If the operation of the decoder is disabled, a logical one will be present at all its outputs.
The functioning of the decoder is described by a system of conjunctions:
Circuit implementation.
High pin count IC packages are notoriously difficult to manufacture and expensive. From this point of view, decoders are extremely unsuccessful circuits, since they have a simple internal structure and a small number of circuit elements, and many external pins. For placement in a regular inexpensive case, only a decoder with 4 information inputs is suitable. There are no larger “sized” decoders in the IC series.
Dimension increase:
The low capacity of standard decryptors raises the question of increasing their capacity. From low-bit decoders it is possible to build a circuit equivalent to a decoder of higher bit capacity. To do this, the input word is divided into fields. The bit depth of the low-order bits field corresponds to the number of inputs of the available decoders. The remaining field of the most significant bits is used to receive signals to enable the operation of one of the decoders that decodes the field of the least significant bits.
As an example in Fig. A diagram of decoding a five-bit binary code using decoders “3-8” and “2-4” is shown. To obtain the required 32 outputs, a column of four “3-8” decoders is compiled. The "2-4" decoder accepts the two most significant bits of the input code. The energized single output of this decoder unlocks one of the column decoders at its enable input. The selected column decoder decrypts the least significant three bits of the input word.
Each input word corresponds to the excitation of only one output. For example, when decoding the word x 4 x 3 x 2 x 1 x 0 = 11001 2 = 25 10, at the input of the first tier decoder there is code 11, which excites its output number three (shown with a cross), which allows the operation of DC4. The code 001 is valid at the DC4 input, so one will appear at its first output, i.e. at the 25th output of the circuit as a whole, which is what is required.
Scheme for reproducing arbitrary logical functions using a decoder .
Decoders, together with OR circuits, can be used to reproduce arbitrary logical functions. By collecting the necessary terms using the OR circuit, you can obtain any function of a given number of arguments.
In Fig. As an example, a diagram for generating two functions is shown 
And 
.
To check the correctness of the scheme, it is convenient to translate the functions F 1 and F 2 into SDNF.
3. Means of information exchange on the Internet. E-mail (The concept of “E-mail”. Methods of working with e-mail.) Search engines (The concept search engine, principles of operation of search engines. Organization of information search on the Internet).
Means of information exchange on the Internet:
Newsgroups (newsgroups)
IRC (Internet Relay Chat, conversation over the Internet) or Chat
Means of communication in real mode time (transfer of text, sound, image) and joint work with applications
Internet paging
Internet telephony
Audio and video conferences
Email- a means of exchanging electronic letters between people with access to a computer network.
Ways to work with email
Through an email client installed on the user's computer (an email program such as Outlook, Bat, etc.).
working directly with a mail server (directly with a corporate mail server, aayandex server, mail.ru, etc.) via a web interface
Search system- a software and hardware complex with a web interface that provides the ability to search for information on the Internet. A search engine usually means a website on which the system interface is located. Software part search engine is search engine (search engine) - a set of programs that provides the functionality of a search engine and is usually a trade secret of the search engine developer company.
Related information.
Rice. 12. Mixed topology
Only in a network with a full mesh topology there is a separate communication line to connect each pair of computers. In all other cases, the question inevitably arises of how to organize the sharing of communication lines by several computers on the network. As always when sharing resources, the main goal here is to reduce the cost of the network.
IN computer networks They use both individual communication lines between computers and shared ones, when one communication line is alternately used by several computers. In the case of using shared communication lines, a complex of problems arises associated with their joint use, which includes both purely electrical problems of ensuring the required quality of signals when connecting several receivers and transmitters to the same wire, and logical problems of dividing access to these lines in time .
Exist various ways solving the organization's problem sharing to shared communication lines. Inside the computer, there are problems separating communication lines between various modules also exist - an example is access to the system bus, which is controlled either by the processor or a special bus arbiter. In networks, organizing shared access to communication lines has its own specifics due to the significantly longer time it takes for signals to propagate over long wires; moreover, this time can be different for different pairs of computers. Because of this, link access negotiation procedures can take an excessive amount of time and lead to significant losses in network performance.
Despite all these difficulties, in local networks shared communication lines are used very often. However, in last years There has been a tendency to abandon shared data transmission media in local networks. This is due to the fact that the reduction in network cost achieved in this way comes at the cost of performance.
An important problem that needs to be taken into account when connecting three or more computers is the problem of their addressing. There are several requirements for the network node address and its destination scheme.
The address must uniquely identify a computer on a network of any size.
The address must have a hierarchical structure, convenient for building large networks.
The address must be convenient for network users, which means that it must have a symbolic representation, for example, www.cisco.com.
Since all of the above requirements are difficult to combine within the framework of any one addressing scheme, in practice several schemes are usually used at once, so that the computer simultaneously has several address-names. Each address is used in the situation when the corresponding type of addressing is most convenient. And so that there is no confusion and the computer is always uniquely identified by its address, special auxiliary protocols are used that can determine addresses of other types using an address of one type.
The most widely used are two node addressing schemes.
Symbolic addresses or names. These addresses are designed to be remembered by people and therefore usually carry meaning. Symbolic addresses are easy to use in both small and large networks. To work in large networks, a symbolic name can have a complex hierarchical structure. All individual pieces of information separated by a "." are called domains. For example, the email address of the Minsk State Linguistic University has next view: mslu.unibel.bv. where mslu is the name of the university, unibel is the name of the provider to which the university server is connected, and by is the abbreviated name of the Republic of Belarus (Byelorussia).
Among the domains, there is a certain hierarchy. The domain at the end of the address is called a domain top level. It identifies the geographic region of the network, its type, or the type of organization to which the message is sent. Thus, in the USA, the last domain usually denotes the type of organization: commercial (.com), educational (.edu), government (.gov), etc.
Numeric compound addresses. Symbolic names are convenient for humans, but due to their variable format and potentially large length, they are not very economical to transmit over a network. Therefore, to work in large networks, numerical compound addresses of fixed and compact formats are used as node addresses. A typical representative of this type of address is an IP address. IP address- This unique name, under which every computer connected to the Internet is known to all other computers in the world. worldwide network. An IP address is usually written as a sequence of four regular decimal numbers, each of which is in the range from 0 to 255. When writing, numbers are separated from each other by dots. For example, 147.120.3.28 or 255.255.255.255 - these are two IP addresses. Whenever a message is sent to any computer on the Internet, the IP address is used to indicate the address of the sender and recipient. To automatically convert domain names of an email address into the IP address of a computer on the Internet, a special program is used - DNS (Domain Names System).
The main directions of using the Internet are: obtaining information and exchanging information. The means of information exchange include:
1. Email.
2. Teleconferences (newsgroups) and mailing lists.
3. File sharing.
4. Audio and video conferences.
5. Programs for communication and collaboration in real time.
6. Paging systems.
7. Internet telephony.
Search tools information resources:
1. Search engines.
2. Thematic catalogs.
3. Metasearch engines.
4. Accelerated search programs.
Email(e-mail or e-pistles) is a means of exchanging letters electronically between people with access to a computer network. The basic concept of email is message. A message is understood as text transmitted over communication lines in a network from one user to another. A message can be considered an “electronic” version of a regular letter. An email message or letter consists of two parts: the header of the letter and the body of the letter. The header of the email contains the email addresses of the recipient and sender, its subject and the date it was sent.
To be able to send and receive messages by email, you need a so-called mail package. It usually includes the following programs:
1. Mail server.
2. Transport program.
3. Mail client.
Mail server– a program that forwards messages from mailboxes to other servers or to the user’s computer at the request of his mail client.
The mail server program manages the transmission of messages between clients and the Internet. If you are using a UNIX network operating system, then the UUCP (Unix-to-Unix Copy Protocol) program can serve as a mail server. UNIX systems). When using other networks operating systems The SMTP (Simple Mail Transfer Protocol) program is used as a mail server. This system requires transport program . Such a program delivers messages to mail servers. They can be, for example, a POP (Post Office Protocol) server. mail center) or IMAP (Internet Mail Access Protocol) server. The mail server then delivers the message to the final recipient.
Mail client (mailer) – a program that helps to compose and send electronic messages, receive and display letters on the user’s computer.
The mail client provides the ability to read a received letter and write a response offline, that is, without connecting to the Internet. There are quite a lot of email clients. Thus, for OS/2, Mac OS and UNIX operating systems, the Eudora mail program is used. For computers running Windows OS, they are widely used mail programs Microsoft: MS OUTLOOK, INTERNET MAIL, EXCHANGE, OUTLOOK EXPRESS and Netscape NETSCAPE MESSENGER. To transmit non-text information (audio and video files, multimedia data) by e-mail, the MIME (Multipurpose Internet Mail Extensions) standard is used.
Mailing list server is a program containing data about email addresses clients, answers to frequently asked questions, price lists, etc. Such a server analyzes messages received at its address and makes a decision on how and what to respond. If a message arrives from a new client, the mailing list server automatically remembers the client's email address.
Operations with outgoing messages include:
· preparing a message;
· addressing;
· attaching files to messages;
· sending messages.
Operations with incoming messages include:
· notification of mail arrival;
· reading mail;
· preparing a response;
· redirection;
· organization of message storage or deletion.
Newsgroups (newsgroups) and mailing lists.
Teleconference (newsgroup) – an online forum organized for discussion and exchange of news on a specific topic. Most known system newsgroups is Usenet (User Network). Usenet a global, distributed discussion system with multiple newsgroups hosted on servers around the world.
Teleconferences Usenet News also called newsgroups (news groups). There are several tens of thousands of such groups. Each news group has its own name and hierarchical structure (a group may include several subgroups, each subgroup, in turn, may consist of other subgroups, etc.) For example, a news subgroup containing messages about WWW information systems is included in a large group " Computer Engineering» and has the name comp.infosystems.www (i.e. the “Computer Engineering” group, the “Information Systems” subgroup, the “WWW” subgroup). The comp.infosystems.www subgroup includes 10 smaller subgroups: comp.infosystems.www.misk, comp.infosystems.www.users, comp.infosystems.www.providers, etc. There are news groups where education issues are discussed ( edu.), science (sci.), music (music.), etc. For example, fido.networks.bel-internet is a news group of the FidoNet network dedicated to discussing network problems (networks), in particular, Internet problems in Belarus (bel-internet).
Information stored in archives on newsgroup servers is the titles and descriptions of articles, but not the articles themselves. If desired, the user can also receive full articles.
Thus, newsgroups perform functions similar to mailing lists, but use specialized software and their own protocol to do so. There are several tens of thousands of newsgroups dedicated to various issues, from computer protocols before tourism. Messages sent to a newsgroup server are sent from it to all associated servers on which of this message Not yet. On each server, the message is stored for a limited period of time, so this Internet service has a news nature. The main purpose of using newsgroups is to be able to ask a question to many people at the same time and get an answer or helpful advice from a more experienced colleague.
Like any service on the Internet, teleconferencing uses client/server technology.
News server– a program that provides access to news groups hosted on this server. Example of a news server address news.unibel.by. There are special client programs for working with news servers.
Newsreader (client program for reading news)– a program that uses the NNTP protocol to transmit newsgroup messages from a news server.
An example is Outlook program Express from Internet Explorer, which, in addition to mail protocols, also understands the NNTP news transfer protocol. Its rival colleague from the Netscape suite is the Netscape Collabra program.
There are teleconferences in which preliminary screening of messages that are not related to the topic of the conference is carried out. Such conferences are called moderated .
Moderated (managed) newsgroups are teleconferences in which all messages and replies are monitored moderator (managers) of this group who have the right to select articles.
In contrast, in unmoderated newsgroups, any message sent to the group is posted immediately.
Unmoderated (unmanaged) newsgroups are newsgroups in which anyone can post or reply to a message in that group.
In order to send a message to a particular news group, you need to fill out the standard positions in your mail client:
1) name of the teleconference (Newsgroup);
2) topic (Subject);
3) area of distribution (Distribution);
4) keywords (Keywords);
5) abstract (Summary).
The essence of this service is that information on a certain topic is received by a small (unlike Usenet News) circle of users who have subscribed to this mailing list.
Mailing list topics can be varied, such as studying foreign languages, information Technology etc. Mailing lists can be controlled (moderated) or uncontrolled (unmoderated). Controlled lists have a manager (moderator), whose responsibilities include reading all letters coming to this list and filtering out unnecessary information(the so-called “noise”) and the formation of a selection of letters to be sent to subscribers. The mailing itself is carried out automatically by the mailing server. In unmoderated lists, all letters arriving at the list address are sent automatically. In controlled lists, subscription requires the permission of the moderator, and in uncontrolled lists it is carried out automatically.
