Unit-1: Web technologies lecturenotes P.R.Engineering college

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UNIT 1
WEB ESSENTIALS: CLIENTS, SERVERS AND COMMUNICATION
 INTERNET
The Internet is a global system of interconnected computer networks that use 
the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide. It 
is a network of networks that consists of millions of private, public, academic, 
business, and government networks, of local to global scope, that are linked by a 
broad array of electronic and optical networking technologies. The Internet carries a 
vast range of information resources and services, such as the inter-linked hypertext
documents of the World Wide Web (WWW) and the infrastructure to support 
electronic mail.
A Very Brief History of the Internet
Late 1960's to early 1970's
Dept. of Defense Advanced Research Projects Agency (ARPA)
¨ ARPANET served as basis for early networking research as well as a 
central backbone during the development of the Internet. 
¨ TCP/IP evolved as the standard networking protocol for exchanging data 
between computers on the network. 
Mid-To-Late 1970's 
Basic services were developed that make up the 
Internet: - Remote connectivity 
- File Transfer 
- Electronic mail 
1979-80 
Usenet systems for newsgroups 
1982
Internet gopher
1991
Public introduction to World Wide Web (mostly text based)
- In the early 1990s, the developers at CERN spread word of the 
Web's capabilities to scientific audiences worldwide. 
- By September 1993, the share of Web traffic traversing the NSFNET 
Internet backbone reached 75 gigabytes per month or one percent. By July 1994 it 
was one terabyte per month. 
1994
Prior to this time the WWW was not used for commercial business purposes
- The Internet is one-third research and education network 
- Commercial communications begin to take over the majority of Internet 
trafficIT2353 WEBTECHNOLOGY PREC
2
 BASIC INTERNET PROTOCOLS
The Internet set of networks are all based on IP, the Internet Protocol. ``The 
Internet Protocol (IP) takes care of addressing, or making sure that the routers know 
what to do with your data when it arrives." Data is transmitted in a series of small 
chunks, called packets, each approximately 1200 characters in length. The header of 
each packet includes the destination address of the system to receive the packet. The
address of that system is the IP address. All IP addresses consist of four fields of 
numbers ieach one less than 256. Any packet containing IP addresses in the form
132.246.xxx.xxx
are for systems owned by NRC (actually, it is more precise to say that they are 
destined for systems behind the main NRC National Capital Region router). The 
routers in the network use this number to decide where to forward each packet.
 About TCP/IP
TCP and IP were developed by a Department of Defense (DOD) research 
project to connect a number different networks designed by different vendors into a 
network of networks (the "Internet"). It was initially successful because it delivered a 
few basic services that everyone needs (file transfer, electronic mail, remote logon) 
across a very large number of client and server systems. Several computers in a small 
department can use TCP/IP (along with other protocols) on a single LAN. As with all 
other communications protocol, TCP/IP is composed of layers:
 IP - is responsible for moving packet of data from node to node. IP 
forwards each packet based on a four byte destination address (the IP 
number). The Internet authorities assign ranges of numbers to different 
organizations. The organizations assign groups of their numbers to 
departments. IP operates on gateway machines that move data from 
department to organization to region and then around the world.
 TCP - is responsible for verifying the correct delivery of data from 
client to server. Data can be lost in the intermediate network. TCP adds 
support to detect errors or lost data and to trigger retransmission until 
the data is correctly and completely received.
Sockets - is a name given to the package of subroutines that provide access to
TCP/IP on most systems.
 Network of Lowest Bidders
The Army puts out a bid on a computer and DEC wins the bid. The Air Force puts 
out a bid and IBM wins. The Navy bid is won by Unisys. Then the President decides 
to invade Grenada and the armed forces discover that their computers cannot talk to 
each other. The DOD must build a "network" out of systems each of which, by law, 
was delivered by the lowest bidder on a single contract.IT2353 WEBTECHNOLOGY PREC
3
The Internet Protocol was developed to create a Network of Networks (the 
"Internet"). Individual machines are first connected to a LAN (Ethernet or Token 
Ring). TCP/IP shares the LAN with other uses (a Novell file server, Windows for 
Workgroups peer systems). One device provides the TCP/IP connection between the 
LAN and the rest of the world. To insure that all types of systems from all vendors 
can communicate, TCP/IP is absolutely standardized on the LAN. However, larger 
networks based on long distances and phone lines are more volatile. In the US, many
large corporations would wish to reuse large internal networks based on IBM's SNA.

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Unit-1: Web technologies lecturenotes

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Web technology - Subject

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P.R.Engineering college

Unit-1: Web technologies lecturenotes P.R.Engineering college

Unit-1: Web technologies lecturenotes in Web technology - Subject uploaded at P.R.Engineering college

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