Client-server application software

request to server

Client Server

response to client

Client-server application software involves a client program on the user's computer and server program on a remote computer. The idea is that, instead of running application software on each user's machine, the software and data/files are installed on a remote networked computer (server). The user can request the server to send data, files, graphics, and images and sound as and when needed. Instead of transporting entire files across the network, the server sends just the parts requested, and the software that the client program needs to display the files on the user's screen. What is more, the exchanges of requests and responses between the client computer and the server happen so fast and seamlessly that it appears that the two communicating computers actually connect, exchange data and then disconnect, even if their physical locations are separated by thousands of kilometers.

For instance, when a user wants to send an email, he or she uses email client software to compose the message, to attach email address to it, and to dispatch it, i.e. to send the message to an email server. When the message is delivered, the server takes over, splits the message in datagram's, and sends them on their way into the hotchpotch of interconnected data communication networks. The datagram's find themselves at the server on which the addressee has an email box. After reassembling the datagram's into the original message, the receiving server holds the message until the addressee comes by and collects it (with his email client software).

Sending and receiving an email

sender				message transfer			receiver
email	LINE	email		through		email	LINE	email
client		server		INTERNET		server		client

Vocabulary notes:

router – маршрутизатор;

core – ядро;

sub-network – подсеть;

salient – существенный

hotchpotch – неоднородность

backbone – опорная сеть;

Internet protocol suite – межсетевой протокол;

FTP – программа передачи файлов;

to split – разбивать, дробить;

to attach – прикреплять, присоединять;

to reassemble – повторно собирать;

jumble – беспорядок

III. Complete the phrases with prepositions and use them in sentences of your own:

1. the Internet consists … various data communication backbone segments;

2. the Internet protocol suite can be placed … the top … wide variety of communication networks;

3. to split large messages and data files … smaller packets or 'datagram’s that can be sent easily … one computer … another;

4. to reassemble datagram … the original messages and data files … their final destination;

5. to travel … the jumble of national and international communication networks;

6. to be organized … handle digital signals;

7. files are transmitted … means … client-server application software;

8. to transport entire files … the network;

IV. Complete the following sentences:

1. Indeed, the Internet consists of various national and international data communication backbone segments, …;

2. The strength of the Internet protocol suite is that it …;

3. The key Internet protocols are TCP and IP, which …;

4. To each datagram TCP attaches labels, and these are …;

5. On the Internet, files are transmitted by means …;

6. When a user wants to send an email, he or she uses …

V. Answer the following questions:

1. The Internet is only hardware, isn’t it?

2. What are the protocols and what are they used for?

3. How do computers communicate over the Internet?

VI. Read the second part of the text: