1. 2013Dr. Ali Rodan 1 Handout 1 Fundamentals of the Internet

2. 2013Dr. Ali Rodan 2 The Internet A "network of networks" that consists of millions of smaller domestic, academic, business, and government networks. – Worldwide, publicly accessible Mixing computing and communications technologies. electronic mailonline chatfile transfer World Wide Web Carrying information and services, such as electronic mail, online chat, file transfer, and the interlinked Web pages and other documents of the World Wide Web.

3. 2013Dr. Ali Rodan 3 Packets and Routing Data is transmitted on the internet by packet switching using the standard Internet Protocol (IP) Packet – a unit of information carriage Packet switching – process of moving packets from one node (computer device) to another

4. 2013Dr. Ali Rodan 4 Internet, Packets and Routing At the sender, data is broken into packets and sent to the nearest node (router) At each router, it sends the packet to another router that is closer to the final destination At the receiver, packets are reassembled to get the original data A simple analogy: mailing system

5. 2013Dr. Ali Rodan 5 TCP/IP and Domain Names Basic task of IP – moving packets as quickly as possible from one router to another Yet, it doesn’t check whether packets are delivered successfully, thus need TCP TCP (Transmission Control Protocol) – disassemble/reassemble packets, error checking, ACK packets

6. 2013Dr. Ali Rodan 6 TCP/IP and Domain Names We need some sort of address in order to identify different nodes, as if every house has a mailing address in order to receive mail from others The one used by Internet Protocol is called IP address Every host on the Internet has a unique IP address, made up of four numbers. E.g.. 192.56.215.131, each number is between 0 and 255

7. 2013Dr. Ali Rodan 7 TCP/IP and Domain Names The numbers in an IP address is hard to remember, while names are easier Domain Name System – a mapping between the human-readable name (domain name) of a host and its IP address A domain name consists of two or more parts, e.g. cs.ju.edu.jo The rightmost label conveys the top-level domain, e.g. jo

8. 2013Dr. Ali Rodan 8 TCP/IP and Domain Names Each label to the left specifies a subdomain, in our example, subdomain is ju (University of Jordan), and sub-subdomain is cs (computer science). A top-level domain contains of multiple subdomains, each subdomain can contain multiple sub- subdomain, so on. The database contains the mapping between a domain name and an IP address is stored on a DNS server.

9. 2013Dr. Ali Rodan 9 The World Wide Web Introduced in 1990 by Tim Berners-Lee A system of interlinked, hypertext documents accessed via the Internet. – With a web browser, a user views web pages that may contain text, images, and other multimedia and navigates between them using hyperlinks. – Hypertext refers to text on a computer that will lead the user to other, related information on demand

10. 2013Dr. Ali Rodan 10 World Wide Web hypertext documents are WebPages (documents on the WWW) created using a special kind of document formatting or “markup” language called HyperText Markup Language (HTML). HTML is sent or received over the network using HyperText Transfer Protocol (HTTP).

11. 2013Dr. Ali Rodan 11 What is Web Browser ? A Web browser is a software that enables a user to display and interact with the Web’s rich multimedia content such as text, images, and other information. The Web could be the World Wide Web, a local area network, or a web page on your own machine. Microsoft Internet Explorer or Netscape Navigator – The appearance of a Web page may differ between browsers.

12. 2013Dr. Ali Rodan 12 Client-Server Model A web browser (client) lets a user request a resource. A web server takes the client request and gives something back to the client. Clients and servers know HTML. Client Request Response

13. 2013Dr. Ali Rodan 13 Scripting Languages Scripting languages, which can be embedded within HTML, commonly are used to add functionality to a Web page. Scripting languages came about largely because of the development of the Internet as a communications tool. JavaScript, ASP, JSP, PHP, Perl and Python are examples of scripting languages.InternetJavaScriptASP JSPPHPPerlPython

14. 2013Dr. Ali Rodan 14 URLs and Client-Server Model Each document/resource on the WWW needs to have an identifier in order to be accessed by others. A Uniform Resource Identifier (URI), is a compact string of characters used to identify or name a resource. A Uniform Resource Locator (URL) is a URI which provides means of obtaining the resource by describing its network “location”.

15. 2013Dr. Ali Rodan 15 URL & Hyperlinks URL (Uniform/Universal Resource Locator) – Web page address – typing in Address field HTTP (HyperText Transfer Protocol) – Protocol for transferring data over the Internet HTTPS (Secure HyperText Transfer Protocol) – Protocol for transferring encrypted data over the Internet. Hyperlinks – Graphical or textual elements Click to link to another Web page Loads new page into browser window

16. 2013Dr. Ali Rodan 16 URLs and Client-Server Model Two things are given by the URL – Exact location of the document – The method or protocol by which to retrieve and display the document Example, http://www2.ju.edu.jo/sites/academic/a.rodan/default.aspx http:// – specifies the protocol www2.ju.edu.jo – specifies the host name / domain name sites/academic/a.rodan/default.aspx – specifies the path of the document on the host

17. 2013Dr. Ali Rodan 17 Goal of This Course HTML – Focuses on writing HTML files. JavaScript – Teaches programming language and programming language principles. Client-side applications – Teaches how to create Internet-based and Web- based applications.

18. 2013Dr. Ali Rodan 18 Online Resources http://www.w3.org/ – The World Wide Web Consortium (W3C). http://www.w3schools.com/ – Full Web Building Tutorials - All Free

19. 2013Dr. Ali Rodan 19 Putting it All Together