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Web Server Technology

Web Server Technology. The Internet. The Internet is a global WAN – a network of networks It is based on a client-server network model Hundreds of thousands of web-servers throughout the world provide resources and services to millions of clients

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Web Server Technology

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  1. Web Server Technology Unit 10 Website Design and Development

  2. The Internet • The Internet is a global WAN – a network of networks • It is based on a client-server network model Hundreds of thousands of web-servers throughout the world provide resources and services to millions of clients • Communication between computers on the Internet largely takes place using the TCP/IP protocol, although other protocols, such as FTP, are also used Unit 10 Website Design and Development

  3. How the web works • The client-server model • Client and server operate on machines which are able to communicate through a network • The server waits for requests from a client • Server receives a requests from a client • Performs a the requested work • Or lookup the requested data • And send a response to the client • Servers: file servers, web servers, name servers • Clients: browsers, email clients Unit 10 Website Design and Development

  4. Web browsers and servers • A browser: is a program that can retrieve files from the world wide web and render text, images, or sounds encoded in the files. • i.e. IE, Chrome, Mozilla • A web server: is an application which waits for client requests, fetches requested documents from disk and transmits them the client. • i.eApache • Microsoft (IIS) • Sun What is the market share of these Web Servers? Unit 10 Website Design and Development

  5. The Application Layer Protocols Layer 7 of the OSI 7 Layer model is called the application layer. • This layer defines Application layer protocols. • The most common application layer protocols used between clients and web servers include: • HTTP (Hyper Text Transfer Protocol) • HTTPS (Hyper Text Transfer Protocol Secure) • FTP (File Transfer Protocol) Unit 10 Website Design and Development

  6. URL When a website or page is requested the URL (Uniform Resource Link) is typed into the browser. • A URL tells a webbrowser (e.g. Firefox, Internet Explorer) where to look for a specified resource • Clicking a hyperlink sends a HTTP request to the host web server (HTTP is the is the transfer protocol used for the transfer of pages on the Web. It works in conjunction with TCP/IP) The URL will consist of http://www.hastingsonline.ac.uk/index.html:80 Protocol Server Name The resource (file) *The Port Number What do you remember about DNS? Unit 10 Website Design and Development

  7. url format • <scheme>://<server-domain-name>/<pathname> • <scheme> which protocol to use • http: in general • file: which tells the client the document is on a local machine • ftp: file transfer protocol • <server-domain-name> identifies the server system • i.e. www.sussexcoast.ac.uk • <pathname> tells the server where to find the file • http://sussexcoast.ac.uk/index.html Unit 10 Website Design and Development

  8. Data transmission over the Internet – IP and DNS • Each computer on the Internet has its own unique IP address (e.g. 193.61.29.155) • Users can not possibly remember long, abstract strings of numbers like IP addresses • To make it easier to remember, a Domain Name System (DNS) is used to convert IP addresses to domain names • The DNS has a hierarchical structure with several levels • The root domain (Internet root domain) • Top-level domains (e.g. .edu, .com, .gov, etc.) • Second-level domains (e.g. Amazon, Birkbeck, Google) • Third level domains (sales, finance, Home Office) Unit 10 Website Design and Development

  9. DNS Hierarchical Structure Unit 10 Website Design and Development

  10. DNS TLD’s • TLD’s (Top Level Domains) know about the location of a DNS server for individual domains but only forward the request rather than resolve the request. • Examples of top level domains include: • .com –commercial companies (Verisign) • .org –non-commercial (public interest registry) • .gov –US government use. • .edu –education use. • .ac.uk –UK academic/educational use. • http://www.iana.org Unit 10 Website Design and Development

  11. DNS CCTLD’s • CCTLD’s (Country Code Top Level Domains) • Examples of CCTLD’s and their allocation. • .au –Australia • .bb –Barbados • .ca –Canada • .de –Germany • .is –Iceland • http://www.iana.org Unit 10 Website Design and Development

  12. Task Carry out research into: • The top 3 web servers with the highest market share • Give advantages and disadvantages of each • What are web hosting companies and what services can they offer • The advantages and disadvantages of running web servers vs the use of web hosting companies. Share sources of information with a short summary on to your shared workspace Unit 10 Website Design and Development

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