1. Web and Internet Part I ST: Introduction to Web Interface Design Prof. Angela Guercio Spring 2007

2. What to expect… Title of the course: Web Interface Design Today we focus our attention to the word WEB Today we focus our attention to the word WEB in the next classes we will focus our attention to the word INTERFACE and then to the word DESIGN in the next classes we will focus our attention to the word INTERFACE and then to the word DESIGN

3. Objectives In this lecture, you will learn about: The definition of world wide web The definition of world wide web The difference between Web and Internet. The difference between Web and Internet. The way computers communicate The way computers communicate The protocol of communication of the Internet The protocol of communication of the Internet How computers communicate on a channel. How computers communicate on a channel. Some basic definitions of Web related items Some basic definitions of Web related items The protocol of transmission of the Web \ The protocol of transmission of the Web \

4. Web Interface Design What is the Web? World Wide Web (or shortly WEB) is the premier Internet software application. World Wide Web (or shortly WEB) is the premier Internet software application. It is a application that allows linked documents, called hypertext to run over the Internet It is a application that allows linked documents, called hypertext to run over the Internet The Web uses (is  NOT) the Internet! The Web uses (is  NOT) the Internet!

5. What is the Internet? The Internet (sometimes simply called the Net) is a world-wide interconnected system of networks that connects computers around the world. The Internet (sometimes simply called the Net) is a world-wide interconnected system of networks that connects computers around the world. The word Internet stands for Interconnected Network of networks The word Internet stands for Interconnected Network of networks

6. Internet From the http://www.infosatellite.com/images/articlepics/internet2_usa_map.jpg

7. Network A network is a group of two or more computers that are linked together. A network is a group of two or more computers that are linked together. Two well known types of networks are: Two well known types of networks are: Local Area Networks (LANs) Local Area Networks (LANs) A network that connects computers in a small geographic area A network that connects computers in a small geographic area Computers in the same building or in a group of buildings Computers in the same building or in a group of buildings Computers in the same university small campus (Stark) Computers in the same university small campus (Stark) Wide Area Networks (WANs) Wide Area Networks (WANs) A network of LANs A network of LANs

8. How does the Internet work? Computer exchange packets Computer exchange packets A packet contains a set of data that are addressed to a specific computer A packet contains a set of data that are addressed to a specific computer packet message packet message

9. Traffic The traffic represent the network usage at a given moment. The traffic represent the network usage at a given moment. The data transmitted of the net. The data transmitted of the net. Congestion can cause delay in data transmission Congestion can cause delay in data transmission Internet Traffic Report Internet Traffic Report IN CLASS PRACTICE - Go to IN CLASS PRACTICE - Go to http://www.internettrafficreport.com/main.htm What is the current index in Europe? Which continent has the best traffic performance at the moment? Which router in the continent with the worse performance is the cause of the problem?

10. Router A router is a dedicated machine that selects the best route that the packet should take to go from the source to the destination A router is a dedicated machine that selects the best route that the packet should take to go from the source to the destination Decision is taken according to traffic and other parameters Decision is taken according to traffic and other parameters

11. Pinging Ping is a network tool used to verify if another computer is active or not. Ping is a network tool used to verify if another computer is active or not. How it works? How it works? The program sends to the other computer an “echo request” (Ping?) message which is made of 4 packets The program sends to the other computer an “echo request” (Ping?) message which is made of 4 packets The data are sent over the Net and if received the target replies with “echo response” (Pong!) The data are sent over the Net and if received the target replies with “echo response” (Pong!) The tool measures the time for the round trip as well as the number of packets that got lost The tool measures the time for the round trip as well as the number of packets that got lost No reply indicates that the target is not active. No reply indicates that the target is not active.

12. Pinging IN CLASS PRACTICE: How to ping? 1. Open the Command Prompt 2. type ping followed by the name or the IP address of the computer that you want to ping

13. Internet Services The Internet is a client-service architecture The Internet is a client-service architecture A server is a shared machines that provides a service to other machines A server is a shared machines that provides a service to other machines Ex. A Web Server is a machine dedicated to sending, storing and receiving Web Page documents Ex. A Web Server is a machine dedicated to sending, storing and receiving Web Page documents A client is a machine that asks for services or resources from a server A client is a machine that asks for services or resources from a server

14. TCP/IP The protocol of communication of the Internet is the TCP/IP The protocol of communication of the Internet is the TCP/IP TCP = Transmission Control Protocol TCP = Transmission Control Protocol It ensures the reliable delivery of the packets It ensures the reliable delivery of the packets IP = Internet Protocol IP = Internet Protocol It takes care of how the packets are routed It takes care of how the packets are routed

15. IP address The IP Address is similar to a phone number or a postal address The IP Address is similar to a phone number or a postal address Each server and client have a unique address Each server and client have a unique address (the logical name) loki.cs.kent.edu or the corresponding numerical (IP address) 131.123.35.15

16. loki.cs.kent.edu T op- L evel D omain T op- L evel D omain comedugovmilnetorg comedugovmilnetorg.it.au.jp.fr.de.uk.it.au.jp.fr.de.uk Exercise: What is your IP address? Open your Command Prompt Type ipconfig IP address (cont.) Domain name Machine name

17. Matching host names and IP addresses If you have the logical name and you want to find the IP address, open the Command Prompt and type: If you have the logical name and you want to find the IP address, open the Command Prompt and type: nslookup logical_name nslookup logical_name

18. How to get on the Internet? Technologies: Technologies: Dial-up Dial-up Requires the use of a modem and a telephone line Requires the use of a modem and a telephone line Slow (56 Kbps) Slow (56 Kbps) ADSL (Asymmetric Digital Subscriber Line) ADSL (Asymmetric Digital Subscriber Line) It is DSL technology that transmits over the telephone network in a faster way than the conventional modem. It is DSL technology that transmits over the telephone network in a faster way than the conventional modem. Range from 256 kbit/s (kilobits per second) to 24,000kbit/s, depending on DSL technology, line conditions and service level implemented. Range from 256 kbit/s (kilobits per second) to 24,000kbit/s, depending on DSL technology, line conditions and service level implemented. Data are transmitted at a frequency that are higher that the human voice so they not interfere with the telephone voice communication. Data are transmitted at a frequency that are higher that the human voice so they not interfere with the telephone voice communication. Digital Cable Digital Cable Requires the use of a cable modem (512 Kbps up to 11Mbps) that transfers the data over the cable television infrastructure Requires the use of a cable modem (512 Kbps up to 11Mbps) that transfers the data over the cable television infrastructure

19. What is the Web? Returning back to the word Web…. Returning back to the word Web…. World Wide Web (or shortly WEB) is the premier Internet software application. World Wide Web (or shortly WEB) is the premier Internet software application. It is a application that allows linked documents, called hypertext, to run over the Internet It is a application that allows linked documents, called hypertext, to run over the InternetQuestion: How do I access a document?

20. URL A URL (Uniform Resource Locator) is the global address of documents and other resources that are on the Web. A URL (Uniform Resource Locator) is the global address of documents and other resources that are on the Web. It is formed by a IP address or the domain name and the protocol (ex. http) that should be used to access the page It is formed by a IP address or the domain name and the protocol (ex. http) that should be used to access the pageEx: http://www.cnn.com http://www.cnn.com http://www.cnn.com ftp://cs.kent.edu/~aguercio/index.html ftp://cs.kent.edu/~aguercio/index.html ftp://cs.kent.edu/~aguercio/index.html

21. Web Protocols HTTP (Hyper Text Transfer Protocol) describes how messages are formatted and transmitted from the Web server to the Web browser. HTTP (Hyper Text Transfer Protocol) describes how messages are formatted and transmitted from the Web server to the Web browser. FTP (File Transfer Protocol) is used to transfer files from one machine to another over the Internet. FTP (File Transfer Protocol) is used to transfer files from one machine to another over the Internet. It works in similar way as HTTP which transfer pages but it is used to transfer files It works in similar way as HTTP which transfer pages but it is used to transfer files

22. Other Web terms…. Web Bowser: The software application that displays Web pages Web Bowser: The software application that displays Web pages Netscape Netscape Internet Explorer Internet Explorer SeaMonkey SeaMonkey Mozilla Firefox Mozilla Firefox Web server: the computer that serves the requests sent from the Web Browsers Web server: the computer that serves the requests sent from the Web Browsers

23. Other Web terms….(cont.) Web Page: is a document on the Web. Web Page: is a document on the Web. It is accessed with a unique URL address It is accessed with a unique URL address It may contain any type of media such as text, images, sounds, video. It may contain any type of media such as text, images, sounds, video. The document is called hypertext because it contains hyperlinks to other documents. The document is called hypertext because it contains hyperlinks to other documents.

24. Other Web terms….(cont.) Hyperlink: is an element of an electronic document which indicates an address in the same document or outside the document. Hyperlink: is an element of an electronic document which indicates an address in the same document or outside the document. To follow the link, click on it and you will be moved from the current document to the referred one. To follow the link, click on it and you will be moved from the current document to the referred one.

25. Conclusion We have learned…. The definition of Internet and of World Wide Web The definition of Internet and of World Wide Web How computers communicate over the Internet How computers communicate over the Internet How to get connected to the Internet How to get connected to the Internet Basic terminology related to the Internet and to the Web. Basic terminology related to the Internet and to the Web.