PPT ON INTERNET AND WORLD WIDE WEB

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Internet And World Wide Web Presentation Transcript:
1.The World Wide Web

2.The World Wide Web
1989-1990 – Tim Berners-Lee invents the World Wide Web
Means for transferring text and graphics simultaneously
Client/Server data transfer protocol
Communication via application level protocol
Text mark up language
Simple and easy to use
Requires a client application to render text/graphics

3.Architecture
The WWW today is a distributed client-server service, in which a client using a browser can access a service using a server. However, the service provided is distributed over many locations called sites. Each site holds one or more documents, referred to as Web pages. Each Web page, however, can contain some links to other Web pages in the same or other sites. In other words, a Web page can be simple or composite. 

4.    Assume we need to retrieve a Web page that contains the biography of a famous character with some pictures, which are embedded in the page itself. Since the pictures are not stored as separate files, the whole document is a simple Web page. It can be retrieved using one single request/ response transaction.

5.    Now assume we need to retrieve a scientific document that contains one reference to another text file and one reference to a large image. The main document and the image are stored in two separate files in the same site (file A and file B); the referenced text file is stored in another site (file C). Since we are dealing with three different files, we need three transactions if we want to see the whole document. The first transaction (request/response) retrieves a copy of the main document (file A), which has a reference (pointer) to the second and the third files.

6. A very important point we need to remember is that file A, file B, and file C in Example 2 are independent Web pages, each with independent names and addresses. Although references to file B or C are included in file A, it does not mean that each of these files cannot be retrieved independently. A second user can retrieve file B with one transaction. A third user can retrieve file C with one transaction.

7.The World Wide Web Components
Structural Components
Clients/browsers – to dominant implementations
Servers – run on sophisticated hardware
Caches – many interesting implementations
Internet – the global infrastructure which facilitates data transfer
Semantic Components
Hyper Text Transfer Protocol (HTTP)
Hyper Text Markup Language (HTML)
eXtensible Markup Language (XML)
Uniform Resource Identifiers (URIs)

8.The World Wide Web Structure
Clients use browser application to send URIs via HTTP to servers requesting a Web page
Web pages constructed using HTML (or other markup language) and consist of text, graphics, sounds plus embedded files
Servers (or caches) respond with requested Web page
Or with error message
Client’s browser renders Web page returned by server
Page is written using Hyper Text Markup Language (HTML)
Displaying text, graphics and sound in browser
Writing data as well
The entire system runs over standard networking protocols (TCP/IP, DNS,…)

9.Uniform Resource Identifiers
Web resources need names/identifiers – Uniform Resource Identifiers (URIs)
Resource can reside anywhere on the Internet
URIs are a some what abstract notion
A pointer to a resource to which request methods can be applied to generate potentially different responses
A request method is eg. fetching or changing the object
Most popular form of a URI is the Uniform Resource Locator (URL)

10.WEB Documents

11.Overview of Network Security

12.What is “Security”
Freedom from risk or danger; safety.
2.     Freedom from doubt, anxiety, or fear; confidence.

3.     Something that gives or assures safety, as:
 A group or department of private guards: Call building security if a visitor acts suspicious.
 Measures adopted by a government to prevent attack.
 Measures adopted, as by a business or homeowner, to prevent a crime

13.Why do we need security?
Protect vital information while still allowing access to those who need it
Trade secrets, medical records, etc.
Provide authentication and access control for resources
Guarantee availability of resources

14.Who is vulnerable?
Financial institutions and banks
Internet service providers
Pharmaceutical companies
Government and defense agencies
Contractors to various government agencies
Multinational corporations
ANYONE ON THE NETWORK

15.The Problem of Network Security
The Internet allows an attacker to attack from anywhere in the world from their home desk.
They just need to find one vulnerability:  a security analyst need to close every vulnerability.

Source: Power Point Presentations

PPT ON INTRODUCTION TO INTERNET

Presentation On Introduction To Internet
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Introduction To Internet Presentation Transcript:
1.Internet

2.Intoduction
A computer network, often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications among users and allows users to share resources. 
A computer network allows sharing of resources and information among interconnected devices.
 In the 1960s, the Advanced Research Projects Agency (ARPA) started funding the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. 

3.It was the first computer network in the world.Development of the network began in 1969, based on designs developed during the 1960s. 

4.Purpose
Computer networks can be used for several purposes:
Facilitating communications. Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.
Sharing hardware. In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printer.

5.Sharing files, data, and information. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks.
Sharing software. Users connected to a network may run application programs on remote computers.
Information preservation.

6.Types of networks based on physical scope
Local area network
A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. 

7.Personal area network
A personal area network (PAN) is a computer network used for communication among computer and different information technological devices close to one person. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless devices. The reach of a PAN typically extends to 10 meters.

8.Wide area network
A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. 

9.Metropolitan area network
A Metropolitan area network is a large computer network that usually spans a city or a large campus.

10.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

Source: Power Point Presentations

PPT ON THE INTERNET, INTRANETS AND EXTRANETS

Presentation On The Internet, Intranets, and Extranets
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The Internet, Intranets, and Extranets   Presentation Transcript:

1. An Overview of Telecommunications and Networks
Telecommunications: the electronic transmission of signals for communications
Telecommunications medium: anything that carries an electronic signal and interfaces between a sending device and a receiving device

2. Networks
Computer network: the communications media, devices, and software needed to connect two or more computer systems or devices
Network nodes: the computers and devices on the networks

3. Basic Processing Strategies
Centralized processing: all processing occurs in a single location or facility
Decentralized processing: processing devices are placed at various remote locations
Distributed processing: computers are placed at remote locations but connected to each other via a network

4. Terminal-to-Host, File Server, and Client/Server Systems
Connecting computers in distributed information processing:
Terminal-to-host: the application and database reside on one host computer, and the user interacts with the application and data using a “dumb” terminal
File server: the application and database reside on the one host computer, called the file server
Client/server: multiple computer platforms are dedicated to special functions, such as database management, printing, communications, and program execution

5. Network Types
Personal area network (PAN)
Local area network (LAN)
Metropolitan area network (MAN)
Wide area network (WAN)
International network

6. Communications Software and Protocols
Communications software: software that provides a number of important functions in a network, such as error checking and data security
Network operating system (NOS)
Network management software
Communications protocol: a standard set of rules that controls a telecommunications connection

 7. Use and Functioning of the Internet
Internet: a collection of interconnected networks, all freely exchanging information
ARPANET
The ancestor of the Internet
A project started by the U.S. Department of Defense (DoD) in 1969
Internet Protocol (IP): communication standard that enables traffic to be routed from one network to another as needed

8. How the Internet Works
The Internet transmits data from one computer (called a host) to another
If the receiving computer is on a network to which the first computer is directly connected, it can send the message directly
If the receiving computer is not on a network to which the sending computer is connected, the sending computer relays the message to another computer that can forward it

9. The Internet
The internet A network of networks
The internet transmits data from one computer (called a host) to another
Internet networks Linked networks that work much the same way -- they pass data around in packets, each of which carries the addresses of its sender and receiver

10. Internet
Unlike online services, which are centrally controlled, the Internet is decentralized by design. Each Internet computer, called a host, is independent. Its operators can choose which Internet services to use and which local services to make available to the global Internet community. Remarkably, this anarchy by design works exceedingly There are a variety of ways to access the Internet. It is also possible to gain access through a commercial Internet Service Provider (ISP).

11. How the Internet Works
Transport control protocol (TCP)
A protocol that operates at the transport layer and is used in combination with IP by most Internet applications
Backbone
An Internet high-speed, long distance communications links (like a bus; wire that connects nodes)
Uniform resource locator (URL)
An assigned address on the Internet for each computer E.g., http://www.studygalaxy.com/

12. For more please refer our PPT.
Thank You.

Source: Power Point Presentations