support (the communication channel) to transfer the data between two pieces of
equipment. 2. Local Area Network (LAN). Computer networks having a small ...
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D. On Literacy Database 4. Computer Communication Network: E-Mail & INTERNET Mrs. Indu Gupta State Informatics Officer, Rajasthan National Informatics Centre, Jaipur India 1. Introduction Low cost, high computation power user friendly interfaces in desktops have made computers a very popular and useful tool for wide areas of activity. This power remains localised at the desktop, creating an artificial restrictive atmosphere in this age of open interactive systems. Communication merged with computers makes it possible to share developments, thoughts, and costly resources resulting in optimum utilisationof available technology. Any two or more computers connected together form a computer network, which can share resources and files with each other. Communication models essentially means an exchange of information using a commonly understood set of norms known as protocols. Because of varied platforms and internal architecture of the systems, varied communication architecture is available such as DNA (DEC's Distributed Network Architecture), SNA (Systems Network Architecture) etc. International Standards Organisation (ISO) developed a reference model called OSI, Open Systems Interconnection which permits interconnection of systems of different options by respecting the standards and protocols of this model. This model consists of seven layers: Layer 7: the application layer, provides an interface with the OSI transfer mechanism for the user of an open system (such as an operator or an application programme). Layer 6: the presentation layer, permits systems which exchange data to interpret these independently of their syntactical representation in the system. Layer 5: the session layer, defines the organisation of the dialogue between distant applications. Layer 4: the transport layer, guarantees a constant quality of service for data transfer to the higher layer, regardless of the type of network actually used. Layer 3: the network layer, defines the protocol capable of routing the data through one or more intermediate communication nodes. Layer 2: the data link layer, permits the exchange of data without change between adjacent equipment. * Presented at LRC Training Workshop in Jaipur, India (26 Sep. - 5 Oct. 1996)
Layer 1: the physical layer, provides physical support (the communication channel) to transfer the data between two pieces of equipment. 2. Local Area Network (LAN) Computer networks having a small number of nodes, located either in an office or in a building normally within a limited geographical area of a few kilometres is called a LAN. Such networks are owned by organisation themselves. They have high data transfer rates of 10 Mbps (Megabits per second). 3. Wide Area Network (WAN) Computer networks consisting of nodes spread over a wide geographical area like different cities or far off places is called a WAN. The data transfer speeds are relatively lower. National Informatics Centre’s NICNET which connects all District and State Headquarters is an example of such a WAN. 4. Metropolitan Area Network (MAN) A need was felt for connecting the LAN owned by various users within one city. This is possible by laying of optical fibre cables or by laying high speed dedicated telecommunication lines. The MAN are useful as they handle most of the local data traffic thus reducing the effective WAN load, e.g., connecting ministries in New Delhi to the host computer in New Delhi itself. The wide area network cost is very high and it is more economical to share the network by setting up close user groups or virtual networks for the organisation from the managed data network services. The local area network owned by the organisation could have the network connected using routers etc. 5. Services on Computer Networks (1) On-Line Databases Access (2)E-mail (3)INTERNET (4) EDI (5) Remote login facility 6. E-Mail Mail provides a comfortable, flexible environment for sending and receiving electronically. Simply speaking, E-mail is nothing but sending a file from your account across the Internet to someone else’s account. The general format of mail command is: Mail[options][recipients….] 1
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Layer 1: the physical layer, provides physical support (the communication channel) to transfer the data between two pieces of equipment. 2. Local Area Network (LAN) Computer networks having a small number of nodes, located either in an office or in a building normally within a limited geographical area of a few kilometres is called a LAN. Such networks are owned by organisation themselves. They have high data transfer rates of 10 Mbps (Megabits per second). 3. Wide Area Network (WAN) Computer networks consisting of nodes spread over a wide geographical area like different cities or far off places is called a WAN. The data transfer speeds are relatively lower. National Informatics Centre’s NICNET which connects all District and State Headquarters is an example of such a WAN. 4. Metropolitan Area Network (MAN) A need was felt for connecting the LAN owned by various users within one city. This is possible by laying of optical fibre cables or by laying high speed dedicated telecommunication lines. The MAN are useful as they handle most of the local data traffic thus reducing the effective WAN load, e.g., connecting ministries in New Delhi to the host computer in New Delhi itself. The wide area network cost is very high and it is more economical to share the network by setting up close user groups or virtual networks for the organisation from the managed data network services. The local area network owned by the organisation could have the network connected using routers etc. 5. Services on Computer Networks (1) On-Line Databases Access (2)E-mail (3)INTERNET (4) EDI (5) Remote login facility
"Recipients" mean the receivers of the message. Incoming mail is stored in a standard file for each user, called mailbox for that user. When mail is called to read messages, the mailbox is the default place to find them. As messages are read, they are marked to be moved to secondary file for storage, unless specific action is taken, so that the messages need not be seen again. This secondary file is called the box and is normally located in the user’s HOME directory. Messages can also be saved in the files named by the user. Messages remain in secondary file until forcibly removed. 7. Options The options start with a dash (-). Some of the important options are: -e Test for presence of mail -f [file name] Read messages from file name instead of mailbox, mail box is the default name. -H Print header summary only. -i Ignore interrupts. -N Do not print initial header summary. -u user Read User’s mailbox. This is only effective as user’s mailbox is not read protected. -U Convert uucp style of addresses to Internet standards. 8. E-mail practice session #1 (Send yourself a Message) Notes: Please assume as Press (1)
$mail loginname The host will reply with a new line saying: Subject: (System)
(2) Test Message Number One (This is the subject of you message). This will move the cursor to the line below Subject: Note that, unlike most word processors, the mail program will not wrap your text at the end of the line. Use the at the end of each line to keep all your text on the screen.
6. E-Mail Mail provides a comfortable, flexible environment for sending and receiving electronically. Simply speaking, E-mail is nothing but sending a file from your account across the Internet to someone else’s account. The general format of mail command is: Mail[options][recipients….] 2
(3) This is my first test message via electronic mail (e-mail) This is my first message via electronic (e-mail). As I type this I am learning the basics of composing and sending text messages. Soon I will be able to send e-mail like this to anyone with an email address.
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4) Press The system will reply with EOT (end of text) and the host prompts will appear. These four steps will constitute the sending of mail to a user in general. 9. Input Mode Commands (Tilde Escapes) The following important commands may be entered only from input mode by beginning a line with the tilde escape character (~) ~! Shell-command Execute the shell command and return. ~. Simulate end of file (terminate message input) ~? Print a summary of tilde escapes. ~c name… Add the names to the carbon copy (cc) list. ~f (msglist) Forward the specified messages. The messages are inserted into the message without alternation. ~r filename ~< filename Read in the text from specified file. ~s string… Set the subject line to string. ~t name…Add the given names to the To list. 10. E-Mail Practice Session #2 (Send a message to some user say ‘guest’ and yourself. The message text is already ready in a file ‘xx’)
11. E-MAIL PRACTICE SESSION #3 (Reading your messages) When reading mails, mail is in command mode. A header summary of the first several messages are displayed, followed by a prompt indicating mail can accept regular commands. If there is no mail, the system will prompt that there is no mail and host prompt will reappear. Ex Step 1 $ mail The system will display the following; Mail version SMT 4.0 Thu Jan 1 12:00:00 EST type? for help “/var/mail/loginname”: 1 message 1 new >N 1 Logname Sun Jan 1 17:54 Text Message Number One >N 2 Logname Sun Jan 1 18:00 Text Message Number Two
30/852 20/600
New message Message number in the message list. Command prompt of the mail program. Logname tells from whom you the mail. Sun Jan 1 18.00 Day, date and time the message was sent. 20/600 number of lines/number of characters in the message. Text Message… Subject of the message.
N2
(1) $ mail guest loginname The system will prompt with string. Subject: (system) (2) Test message Number two (This is the subject of your message) (3) ~r xx (This will include a message from the file ‘xx’) (4)
Press EOT message will come from system and the host prompt ‘$’ will appear.
Note: Before pressing , you can try other input mode commands. Be sure that all the commands should be given at first column if a line i.e. a the beginning of a line.
Step 2: t1 It will display message number 1 on the screen. (The number of following the ‘t’ or ‘p’ tells the mail program which message to type out. If you do not use a number, it will tell the “current” message ). Message 1: From loginname Sun Jan 1 17:54:50 Return-Path: : : To: loginname Subject: Test Message Number One Status: R This is my first test message via electronic mail (e-mail). As I type this I am learning the basics of composing and sending test messages. Soon I will be able to send e-mail like this to anyone with an e-mail address. ? 3
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Note: to see message No. 2, you can use t2 or p2. Regular command (command at ? prompt) are of the form: [command] [msglist] [arguments] If no command is specified in command mode, print is assumed. A msglist is a list of message identifies separated by spaces, which may include: n Message number n . The current message. ^ The first undeleted message. $ The last message. * All messages. n-m An inclusive range of message numbers. user All messages from user. /string All messages with string in the subject line (case ignored). :c All messages of type c, where c is one of: d deleted messages n new messages o old messages r read messages u unread messages Note that the context of the command determines whether this type of message specification makes sense. Default for msglist if the current message. Other arguments are usually arbitrary whose usage depends on the command involved.
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Some of the important mail commands (commands at ?) are: ! Shell-command Execute shall command and return. # Comment Null command (comment). This may be useful in -mailrc files. = Print the current message number. ? Print a summary of commands. copy [filename] copy [msglist] filename Copy messages to the file without marking the messages as saved. Otherwise equivalent to the save command. delete [msglist] Delete messages from the mailbox. If autoprint is set, the next message after the last one is printed. dp [msglist] dt [msglist] Delete the specified messages from the mailbox and print the next message after the last one deleted. Roughly
equivalent to a delete command followed by a print command. edit [msglist] Edit the given messages. exit xit Exit from mail without changing the mailbox. No messages are saved in the mbox. from ‘[msglist] Prints the header summary for the specified message. help prints a summary of commands. hold [msglist] preserve [msglist] Holds the specified messages in the mailbox. list Prints all commands available. No explanation is given. print [msglist] type [msglist] Print the specified messages. If crt is set, the messages longer than the number of lines specified by the crt variable are paged through the command specified by the PAGER variable. The default command is "more"pg. quit Exit from mail, storing messages that were read in mbox and unread messages in the mailbox. Messages that have been explicitly saved in a file are deleted. reply [msglist] respond [msglist] Send a response to the author of each message in the msglist. The subject line is taken from the first message. If records is set to a file name, the response is saved at the end of that file. save [msglist] Save the specified messages in a file whose name is, derived from the author of the first message. The name of the file is taken to be the author’s name with all network addressing stripped off. See also the Copy commands and outfolder. save [filename] save [msglist] filename Save the specified messages in the give file. The file is created if it does not exist. The message is deleted from the mailbox when mail terminates unless keep save is set.
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undelete [msglist] Restore the specified deleted messages. Will only restore messages deleted in the current mail session. If autoprint is set, the last message of those restored is printed. write [msglist] filename Write the given messages on the specified file, minus the header and training blank line. Otherwise equivalent to the save command. Ex 4: Keeping Your Message Step 1: $mail Step 2: p1 Step 3: ? preserve Step 4: ? q The system will display following message.
Ex 5:
Ex 6:
Ex 7:
Ex 8:
Ex 9:
"Held 1 message in/var/mail/loginname” $ Answering a mail. Step 1: $mail Step 2: ? Reply [message] The system will fill ‘To’ and subject line, you have to enter the message text only. Step 3: Here is an answer to our original message. Step 4: Saving a mail message. Step 1: $mail Step 2: ?save 1 This will save message ‘1’ or current message in the ‘mbox’. The message will be appended. Step 3: ? preserve Step 4: ? q The system will display following message. "Held 1 message in/var/mail/loginname” $ Saving a message in a file. Step 1: $mail Step 2: ?save 1 myfile This will save the message ‘1’ in the file ‘myfile’. Deleting a mail message. Step 1: $small Step 2: & delete 1 This will erase the message ‘1’. Viewing mail commands. Step 1: $mail Step 2: ?? It will display mail commands.
mail commands type next
print messages goto and type next message
edit messages give header lines of messages delete [msglist] delete messages undelete [msglist] restore delete messages save [msglist] fileappend messages to file reply [msglist] reply to message, including all recipients Reply [msglist] reply to the authors of the messages preserve [msglist] preserve messages in mailbox mail user mail to specific user quit quit, preserving unread messages xit quit, preserving all messages header print page of active message headers !command shell escape cd [directory] chdir to directory or home if none given list list all commands (no explanations) top [msglist] print top 5 lines of messages z [+/–] display next [last] page of 10 headers [msglist] is optional and specifies messages by number, author, subject or type. The default is the current message. edit [msglist] from [msglist]
Internet E-mail Addresses An Internet E-mail address consists of (i) login name (ii) host name and (iii) domain name General format of E-mail address is: @host_name.domain_name.logname The host_name .domain_name makes full host name of system e.g.
[email protected] [email protected] [email protected] In the above E-mail address: user1, guest and user5 Login names. Alpha, hub and beta Systems names nic.in Domain name. Ex 10: Sending a mail to another system. As an example, let us send an E-mail to the address
[email protected] Step 1: $ mail
[email protected] The system will display ‘Subject :’string and ask you to enter subject of the message (step 2) Step 2: This is a test mail from alpha m/c. (subject of the message) Step 3: Enter following text in the body of message. Step 4: 5
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INTERNETNAVIGATINGTOOLS With a resource as large as the Internet, just finding the information or software or resources we need can be quite challenging. Fortunately, there is a set of tools that enables us to find what we are looking for in a relatively comfortable and productive way. In particular, we will focus on four tools: 1. Gopher - A utility that permits us to ‘go for’ information in lots of places. 2. Archie - A utility that permits us to find files that we can then ‘send’ to our own computer. 3. WAIS - A Wide Area Information Server utility that permits us to look for information on a variety of hosts without having to be connected with where the information is located, or how to get to it. 4. World Wide Web - A system that provides access to documents wherever they are located. Each one of these serves a particular purpose. Mastery of all four of them can directly enhance our ability to use the Internet more effectively. GOPHER PRACTICE SESSION #1 Step 1. Login to your host computer. Step 2. Type the following command: (at the command prompt: $) Gopher Step 3. You will get a screen as follows: Root gopher server: gopher.tc.umn.edu. 1. Information About Gopher/ 2. Computer Information/ 3. Internet file server (ftp) sites/ • • Press? For help, q to Quit, u to go up a menu Page: 1/1 The Main Gopher Screen. Note: To select any item in the menu, use up or down arrow keys to move the ‘pointer’ (— >) up or down. Press to select, or, you may just type the number of your selection, and then press . Step 4: Select any item. Step 5: Press q to Quit. You should be back at your host prompt. GOPHER PRACTICE SESSION #2 Step 1. To start the Gopher program again, type the command and gopher at the UNIX system prompt. The main Gopher screen appears.
Gopher
At the end of each menu choices is a special character (or group of characters) that tells you what the menu 6
item will do. Menu items that end with a slash (/) will take you to another menu with more choices. Menu items that end with the characters allow you to search through a database. Menu items that end with a period (.) are files that will be down loaded (with D option) and displayed when you select them. Step 2. Select item 1, which gives more information about Gopher. Select item 1 Step 3. Move back to the main menu by using the u command. Type u Step 4. Select item 8, other Gopher and Information Servers, to see another interesting screen. Select item 8 Step 5. On this menu, select item 1 (All the Gopher Servers in the World). This menu alphabetically lists Gopher servers set up around the World. Select Item 1 Step 6. Return to the other Gopher and Information Servers screen by typing u. Type u Step.7. Selecting item 3 on this menu brings up the Search titles in Gopherspace using veronica menu. Select Item 3 Step 8. Select item 10, FAQ (FrequentlyAsked Questions about veronica) to know more about veronica (another navigating tool). Select Item 10 Step 9. Press S to Save or D to Download this FAQ file. Step 10. As an example search, you should select item 3.
Find GOPHER DIRECTORIES by Title Word(s) (Via NYSERNet) Step 11. When the system asks what you want to search or, type Clinton. Press Enter to begin the search, to move to next screen of menu, b for previous screen and u to exit. You can use similar techniques to look for Gopher menu titles for almost any topic. GLOSSARY OF TERMS FOR INTERNET RESOURCES Archie – A tool (software) for finding files stored on anonymous FTP sites. You need to know the exact file name or a sub-string of it. ARPANet (Advanced Research Projects Administration Network) – The precursor to the Internet.
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Developed in the 60’s and early 70‘s by the US Department of Defence as an experiment in side-area networking that would survive a nuclear war. Anonymous FTP (File Transfer Protocol) – The procedure of connecting to a remote computer, as an anonymous or guest user, in order to transfer public files back to your local computer. (See also: FTP and Protocols) Bandwidth – A measure of how much “stuff” you can send thorough a connection. Usually measured in bitsper-second. BBS (Bulletin Board System) – A computerised meeting and announcement system that allows people to carry on discussions, upload and download files and make announcements without the people being connected to the computer at the same time. BITNET – A cooperative computer network interconnecting over 2,300 academic and research institutions in 32 countries. Originally based on IBM’s RSCS networking protocol. BITNET supports mail, mailing lists, and file transfer. Now merging with CSNET and running the RSCS protocol over TCP/IP protocol (BITNET II), the network will be called Computer Research and Education Network (CREN). Client-Server Interface – A programme that provides an interface to remote programmes (called clients), most commonly across a network, in order to provide these clients with access to some service such as databases, printing, etc. In general, the clients act on behalf of a human end-user (perhaps indirectly). CREN – Computer Research and Education Network is the new name for the merged computer networks, BITNET and Computer Science Network (CSNET). It supports electronic mail and file transfer. Domain Name System (DNS) – The Internet naming scheme which consists of a hierarchical sequence of names, from the most specific to the most general (left to right), separated by dots, for example nic.ddn.mil. (See also: IP Address). Downloading – The electronic transfer of information from one computer to another, generally from a larger computer to a smaller one such as a microcomputer. Electronic Bulletin Board – A shared file where users can enter information for other users to read or download. Many bulletin boards are set up according to general topics and are accessible throughout a network. FAQ (Frequently Asked Questions) – FAQs are documents that lit and answer the most common questions
on a particular subject. There are hundreds of FAQs on diverse subjects. FAQs are usually written by people who have tired of answering the same question over and over. FTP – File Transfer Protocol allows a user to transfer files electronically from remote computers back to the user’s computer. Part of the TCP/IP/TELNET software suite. Gateway – Used in different senses (e.g., Mail Gateway, IP Gateway), but most generally, a computer that forwards and routes data between two or more networks of any size. Gopher – Gopher is a client-server program which provides a way to access what we want without having to know where it is. Gopher systems are topical and menu-based; they let you navigate to the information you are looking for on the basis of what kind of information it is, and what subject it is about. Host Computer – In the context of networks, a computer that directly provides service to a user. In contrast to a network server, which provides services to a user through an intermediary host computer. HTML (HyperText Markup Language) – The coding language used to crate Hypertext documents for use on the World Wide Web. In HTML you can specify that a block of text or a word is ‘linked’ to another file on the Internet by surrounding them with codes called "tags", which indicates how they should appear. HTML files are meant to be viewed using a World Wide Web client program, such as Lynx, Mosaic, Netscape, etc. HTTP (HyperText Transport Protocol) – The protocol for moving hypertext files across the Internet. Requires a HTTP Client programme on one end and an HTTP Server programme on the other end. HTTP is the most important protocol used in the World Wide Web Hypertext – Generally, any text that contains “links” to other documents words or phrases in the document that can be chosen by a reader and which cause another document to be retrieved and displayed. Internet – The series of interconnected networks that includes local area, regional, and national backbone networks. Networks in the Internet use the same telecommunications protocol (TCP/IP) and provide electronic mail, remote login, and file transfer services. IP (Internet protocol) – The Internet standard protocol that provides a common layer over dissimilar networks, used to move packets among host computers and through gateways if necessary. 7
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IP Address – The numeric address of a computer connected to the Internet, also called Internet address. Jughead – Jughead, developed at the University of Utah, is a software programme which allows for searching in Gopher menus (see Veronica). It is different from Veronica in that Jughead typically limits searches to the menus of a local on-site Gopher or to the top few levels of Gopher menus around the world. Listserve Lists (or listservers) – Electronic discussion of technical and non-technical issues conducted by electronic mail over BITNET using LISTSERVE protocols. Similar lists, often using the UNIX readnews or rn facility, are available exclusively on the Internet. Internet users may subscribe to BITNET listservers. Participants subscribes via a central service, and lists often have a moderator who manages the information flow and content. NIC (Network Information Centre) – A NIC provides administrative support, user support, and information services for a network. NREN – The National Research and Education Network is a proposed national computer network to be build upon the foundation of the NSF backbone network, NSFnet. NREN would provide high speed interconnection between other national and regional networks. SB 1067 is the legislative bill proposing NREN. OPAC – Online Public Access Catalog, a term used to describe any type of computerised library catalog. OSI (Open Systems Interconnection) – This is the evolving international standard under development at ISO (International Standards Organisation) for the interconnection of co-operative computer systems. An open system is one that conforms to OSI standards in its communications with other systems. Protocol – A mutually determined set of formats and procedures governing the exchange of information between systems. Remote Access – The ability to access a computer from outside a building in which it is housed, or outside the library. Remote access requires communications hardware, software, and actual physical links, although this can be as simple as common carrier (telephone) lines or as complex as Telnet login to another computer across the Internet. Shareware – Microcomputer software, distributed through public domain channels, for which the author expects to receive compensation. 8
NOTE: 1 EDSTATS-Plus is developed by UNESCO, Paris and is available free of chargefrom UNESCO Division of Statistics, 7 Place de Fontenoy, 75732 Paris 07SP, France, Fax (33)1-45-66-4844. 2 UNESCO (1995): Guidelines on Preparing a National EDI Report, UNESCO Division of Statistics, Paris. 3 PopMap software is developed by the United Nation Funds for Population Activities and can be obtained free of charge from United Nations, Statistics Division, New York, 10017 (USA), FAX - 1 (212) 963-4116
