Web and InternetWeb and InternetPart IPart I

ST: Introduction to Web Interface Design ST: Introduction to Web Interface Design Prof. Angela GuercioProf. Angela Guercio

Spring 2007Spring 2007

What to expect…What to expect…

Title of the course: Title of the course:

Web Interface DesignWeb Interface Design

Today we focus our attention to the Today we focus our attention to the word word WEBWEB

in the next classes we will focus our in the next classes we will focus our attention to the word INTERFACE and attention to the word INTERFACE and then to the word DESIGNthen to the word DESIGN

ObjectivesObjectives

In this lecture, you will learn about:In this lecture, you will learn about:

The definition of world wide webThe definition of world wide web

The difference between Web and Internet.The difference between Web and Internet.

The way computers communicateThe way computers communicate

The protocol of communication of the InternetThe protocol of communication of the Internet

How computers communicate on a channel.How computers communicate on a channel.

Some basic definitions of Web related itemsSome basic definitions of Web related items

The protocol of transmission of the WebThe protocol of transmission of the Web\\

Web Interface DesignWeb Interface Design

What is the Web?What is the Web? World Wide WebWorld Wide Web (or shortly WEB) (or shortly WEB)

is the premier Internet software is the premier Internet software application.application.

It is a application that allows linked It is a application that allows linked documents, called documents, called hypertext hypertext to run to run over the Internetover the Internet

The Web The Web usesuses (is (is NOTNOT) the ) the Internet!Internet!

What is the Internet?What is the Internet?

The Internet (sometimes simply The Internet (sometimes simply called the Net) is a called the Net) is a world-wide world-wide interconnected system of interconnected system of networksnetworks that connects that connects computers around the world.computers around the world.

The word Internet stands for The word Internet stands for InterInterconnected connected NetNetwork of work of networksnetworks

InternetInternetFrom the http://www.infosatellite.com/images/articlepics/internet2_usa_map.jpgFrom the http://www.infosatellite.com/images/articlepics/internet2_usa_map.jpg

NetworkNetwork

A network is a group of two or more A network is a group of two or more computers that are linked together.computers that are linked together.

Two well known types of networks Two well known types of networks are:are: Local Area Networks (LANs)Local Area Networks (LANs)

A network that connects computers in a A network that connects computers in a small geographic areasmall geographic area

Computers in the same building or in a group Computers in the same building or in a group of buildingsof buildings

Computers in the same university small Computers in the same university small campus (Stark)campus (Stark)

Wide Area Networks (WANs)Wide Area Networks (WANs) A network of LANsA network of LANs

How does the Internet work?How does the Internet work?

Computer exchange Computer exchange packetspackets AA packet packet contains a set of data contains a set of data

that are addressed to a specific that are addressed to a specific computercomputer

packet

message

packet

message

TrafficTraffic

The traffic represent the network The traffic represent the network usage at a given moment. usage at a given moment. The data transmitted of the net.The data transmitted of the net.

Congestion can cause delay in data Congestion can cause delay in data transmissiontransmission Internet Traffic ReportInternet Traffic Report

IN CLASS PRACTICE - Go toIN CLASS PRACTICE - Go tohttp://www.internettrafficreport.com/main.htmhttp://www.internettrafficreport.com/main.htmWhat is the current index in Europe?What is the current index in Europe?Which continent has the best traffic Which continent has the best traffic

performance at the moment?performance at the moment?Which router in the continent with the worse Which router in the continent with the worse

performance is the cause of the problem?performance is the cause of the problem?

RouterRouter

A A routerrouter is a dedicated machine that selects is a dedicated machine that selects the best route that the packet should take to the best route that the packet should take to go from the source to the destinationgo from the source to the destination Decision is taken according to traffic and other Decision is taken according to traffic and other

parametersparameters

PingingPinging

PingPing is a network tool used to verify is a network tool used to verify if another computer is active or not.if another computer is active or not.

How it works?How it works? The program sends to the other The program sends to the other

computer an “computer an “echo requestecho request” (Ping?) ” (Ping?) message which is made of 4 packets message which is made of 4 packets

The data are sent over the Net and if The data are sent over the Net and if received the target replies with “received the target replies with “echo echo responseresponse” (Pong!) ” (Pong!)

The tool measures the time for the The tool measures the time for the round trip as well as the number of round trip as well as the number of packets that got lostpackets that got lost

No reply indicates that the target is not No reply indicates that the target is not active.active.

PingingPingingIN CLASS PRACTICE: How to ping? IN CLASS PRACTICE: How to ping? 1.1. Open the Command Prompt Open the Command Prompt 2.2. type type ping ping followed by the name or followed by the name or

the IP address of the computer that the IP address of the computer that you want to pingyou want to ping

Internet ServicesInternet Services

The Internet is a client-service The Internet is a client-service architecturearchitecture A A serverserver is a shared machines that is a shared machines that

provides a service to other machines provides a service to other machines Ex. A Ex. A Web ServerWeb Server is a machine dedicated to is a machine dedicated to

sending, storing and receiving Web Page sending, storing and receiving Web Page documentsdocuments

A A clientclient is a machine that asks for is a machine that asks for services or resources from a serverservices or resources from a server

TCP/IPTCP/IP

The protocol of communication The protocol of communication of the Internet is the TCP/IPof the Internet is the TCP/IP TCP = Transmission Control TCP = Transmission Control

ProtocolProtocol It ensures the reliable delivery of the It ensures the reliable delivery of the

packetspackets IP = Internet ProtocolIP = Internet Protocol

It takes care of how the packets are It takes care of how the packets are routedrouted

IP addressIP address

The IP Address is similar to a phone The IP Address is similar to a phone number or a postal addressnumber or a postal address Each server and client have a unique Each server and client have a unique

address address (the logical name)(the logical name)

loki.cs.kent.eduloki.cs.kent.eduor the corresponding numerical or the corresponding numerical

(IP address)(IP address)

131.123.35.15131.123.35.15

loki.loki.cscs..kent.edukent.edu

TTop-op-LLevel evel DDomainomain comcom eduedu govgov milmil netnet orgorg .it.it .au.au .jp.jp .fr.fr .de.de .uk.uk

Exercise: What is your IP address?Open your Command PromptType ipconfig

IP address (cont.)IP address (cont.)

Domain nameDomain nameMachine nameMachine name

Matching host names and IP Matching host names and IP addresses addresses If you have the logical name If you have the logical name

and you want to find the IP and you want to find the IP address, open the Command address, open the Command Prompt and type:Prompt and type:nslookupnslookup logical_namelogical_name

How to get on the Internet? How to get on the Internet?

Technologies:Technologies: Dial-upDial-up

Requires the use of a Requires the use of a modemmodem and a telephone line 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 It is DSL technology that transmits over the

telephone network in a faster way than the telephone network in a faster way than the conventional modem. conventional modem.

Range from 256 kbit/s (kilobits per second) to Range from 256 kbit/s (kilobits per second) to 24,000kbit/s, depending on DSL technology, line 24,000kbit/s, depending on DSL technology, line conditions and service level implemented. conditions and service level implemented.

Data are transmitted at a frequency that are higher Data are transmitted at a frequency that are higher that the human voice so they not interfere with the that the human voice so they not interfere with the telephone voice communication.telephone voice communication.

Digital CableDigital Cable Requires the use of a cable modem (512 Kbps up Requires the use of a cable modem (512 Kbps up

to 11Mbps) that transfers the data over the cable to 11Mbps) that transfers the data over the cable television infrastructuretelevision infrastructure

What is the Web?What is the Web?

Returning back to the word Web….Returning back to the word Web…. World Wide WebWorld Wide Web (or shortly WEB) is (or shortly WEB) is

the premier Internet software the premier Internet software applicationapplication.. It is a application that allows linked It is a application that allows linked

documents, called documents, called hypertext, hypertext, to run over to run over the Internetthe Internet

Question:Question:

How do I access a document?How do I access a document?

URLURL

A URL (Uniform Resource Locator) is A URL (Uniform Resource Locator) is the global address of documents and the global address of documents and other resources that are on the Web.other resources that are on the Web. It is formed by a IP address or the It is formed by a IP address or the

domain name and the protocol (ex. http) domain name and the protocol (ex. http) that should be used to access the page that should be used to access the page

Ex:Ex: http://http://www.cnn.comwww.cnn.com ftp://cs.kent.edu/~aguercio/index.htmlftp://cs.kent.edu/~aguercio/index.html

Web ProtocolsWeb Protocols

HTTP (Hyper Text Transfer Protocol) HTTP (Hyper Text Transfer Protocol) describes how messages are describes how messages are formatted and transmitted from the formatted and transmitted from the Web server to the Web browser.Web server to the Web browser.

FTP (File Transfer Protocol) is used FTP (File Transfer Protocol) is used to transfer files from one machine to to transfer files from one machine to another over the Internet. another over the Internet. It works in similar way as HTTP which It works in similar way as HTTP which

transfer pages but it is used to transfer transfer pages but it is used to transfer filesfiles

Other Web terms….Other Web terms….

Web Bowser:Web Bowser: The software The software application that displays Web pagesapplication that displays Web pages NetscapeNetscape Internet ExplorerInternet Explorer SeaMonkeySeaMonkey Mozilla FirefoxMozilla Firefox

Web server:Web server: the computer that serves the computer that serves the requests sent from the Web the requests sent from the Web BrowsersBrowsers

Other Web terms….(cont.)Other Web terms….(cont.)

Web Page:Web Page: is a document on the is a document on the Web. Web. It is accessed with a unique URL It is accessed with a unique URL

addressaddress It may contain any type of media It may contain any type of media

such as text, images, sounds, such as text, images, sounds, video.video.

The document is called The document is called hypertexthypertext because it contains because it contains hyperlinkshyperlinks to to other documents.other documents.

Other Web terms….(cont.)Other Web terms….(cont.)

Hyperlink:Hyperlink: is an element of an is an element of an electronic document which electronic document which indicates an address in the indicates an address in the same document or outside the same document or outside the document. document. To follow the link, click on it and To follow the link, click on it and

you will be moved from the current you will be moved from the current document to the referred one.document to the referred one.

ConclusionConclusion

We have learned….We have learned….

The definition of Internet and of World The definition of Internet and of World Wide WebWide Web

How computers communicate over the How computers communicate over the InternetInternet

How to get connected to the InternetHow to get connected to the Internet

Basic terminology related to the Internet Basic terminology related to the Internet and to the Web.and to the Web.