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Web and http computer network
- 1. Presented by: Anil Pokhrel BscCSIT5th sem College of Applied Business 1
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- 4. 4 Introduction • The WorldWide Web is a way of exchanging information between computers on the Internet. • The World Wide Web is the network of pages of images, texts and sounds on the Internet which can be viewed using browser software .
- 5. 5 STRUCTURE Clients usebrowser 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
- 6. 6 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,...)
- 7. 7 Internet vs Worldwide web • The Internet is a global system of interconnected computer networks. • Its access is provided by ISPs. • It runs applications like www, ftp, html etc • Web is collection of text documents and other resources, linked by hyperlinks and URLs • Usually accessed by web browsers • Its an application running on Internet
- 8. 8 WWW 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
- 9. 9 Semantic Components: Hyper TextTransfer Protocol (HTTP) Hyper Text Markup Language (HTML) extensible Markup Language (XML) Uniform Resource Identifiers (URIs)
- 10. 10 The Fundamental concept TheHypertext concept Hypertext is text which contains links to other texts. The term was coined by Ted Nelson around 1965. The Hypermedia concept Hypermedia is a term used for hypertext which is not constrained to be text: it can include graphics, video and sound.
- 11. 11 Continue….. WEB Browser • Aweb browser displays a web document and enables users to access web documents. WEB Server • This is a program that waits patiently for the browser to request a web page. The servers looks for the requested information, retrieves it and send it to the browser or sends an error message if the file is not found.
- 12. 12 Uniform Resource Locator(URL) • These are the web addresses. The resource locator is an addressing system .
- 13. 13 Advantages and Disadvantages •Mainly free information • Low cost of initial connection • Rapid interactive communication • Facilitates the exchange of huge volumes of data • Accesible from anywhere • Has become the global media • Danger of overload and excess information • Difficult to filter and prioritize information • No guarantee of finding what one is looking for • No regulation • No quality control over available data
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- 15. 15 The Hypertext TransferProtocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. This is the foundation for data communication for the World Wide Web (i.e. internet) since 1990. Basically, HTTP is a TCP/IP based communication protocol, that is used to deliver data (HTML files, image files, query results, etc.) on the World Wide Web.
- 16. 16 Basic features HTTP isconnectionless HTTP is media independent HTTP is stateless
- 17. 17 Basic architecture The HTTPprotocol is a request/response protocol based on the client/server based architecture where web browsers act like HTTP clients, and the Web server acts as a server
- 18. 18 How http works? Client The HTTP client sends a request to the server in the form of a request method, URI, and protocol version, containing request modifiers, client information, and possible body content over a TCP/IP connection . Server The HTTP server responds with a status line, including the message's protocol version and a success or error code, containing server information, and possible entity-body content.
- 19. 19 Request method GET :The GET method is used to retrieve information from the given server using a given URI. Requests using GET should only retrieve data and should have no other effect on the data. HEAD : Same as GET, but it transfers the status line and the header section only. POST : A POST request is used to send data to the server, for example, customer information, file upload, etc. using HTML forms. PUT : Replaces all the current representations of the target resource with the uploaded content.
- 20. 20 DELETE : Removesall the current representations of the target resource given by URI. CONNECT : Establishes a tunnel to the server identified by a given URI. OPTIONS : Describe the communication options for the target resource. TRACE : Performs a message loop back test along with the path to the target resource.
- 21. 21 1xx: Informational :It means the request has been received and the process is continuing. 100 continue : only a part of the request has been received by the server ,but as long as it has not been rejected ,the client should continue . 2xx: Success : It means the action was successfully received, understood, and accepted. 201 created : the request is complete ,and a new resource is created 3xx: Redirection : It means further action must be taken in order to complete the request. 4xx: Client Error : It means the request contains incorrect syntax or cannot be fulfilled. 404 not found : the server can not find the requested page 5xx: Server Error : It means the server failed to fulfill an apparently valid request.
- 22. 22 Conclusion 1. HTTP isthe protocol used to transfer data to and from the website. 2. WWW is the identifier that indicates that it is a web site and it uses the HTTP protocol. 3. HTTP://anything.com, WWW.anything.com, HTTP://WWW.anything.com leads to the same site. 4. Any prefix that is not reserved to a protocol can be used as a sub domain.
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