internet and the web lecture

04/12/23 Course Introduction 1

Welcome!Welcome!Web DevelopmentWeb Developmentand Programming and Programming

V22.0380V22.0380

Professor: Sana’ OdehProfessor: Sana’ Odeh

[email protected]@cs.nyu.edu


Getting HelpGetting Help If you need help, you always have If you need help, you always have

three options:three options: Office Hours: Office Hours: everyMON. & everyMON. &

Wed, 1:30 - 3:00 pm Wed, 1:30 - 3:00 pm Office 418, Warren Weaver Office 418, Warren Weaver

HallHall Class Class Tutor: available by Tutor: available by

email and at the lab at 14 email and at the lab at 14 Washington Place (6 hours a Washington Place (6 hours a week) week) to help out with any to help out with any homework questions.homework questions.


Course Web SiteCourse Web Site

The Course Web Site is available at:The Course Web Site is available at:http://cs.nyu.edu/courses/fall04/V22.0380-002/http://cs.nyu.edu/courses/fall04/V22.0380-002/

Let’s check it out…Let’s check it out…


I5 AccountsI5 Accounts If you are registered for this course, you If you are registered for this course, you

already have an i5 account.already have an i5 account. Your i5.nyu.edu system uses NYUHome Your i5.nyu.edu system uses NYUHome

NetID as their username, and their NetID as their username, and their central NYU single sign-on password to central NYU single sign-on password to log in. log in.

You need an active NYUHome account to You need an active NYUHome account to login to your i5 account.login to your i5 account.

To set, or change this password, go to: To set, or change this password, go to: http://start.nyu.eduhttp://start.nyu.edu


Lecture NotesLecture Notes

Most lecture notes will be available Most lecture notes will be available as Power Point Slides.as Power Point Slides.

You can easily download these from You can easily download these from the course web site (more later…)the course web site (more later…)


Foundations of Foundations of the Webthe Web


OutlineOutline Foundation of the Internet and the WebFoundation of the Internet and the Web

History of the Internet and the webHistory of the Internet and the web Internet ServicesInternet Services Internet protocolsInternet protocols Internet termsInternet terms Review of Unix commandsReview of Unix commands Review of Pico text editorReview of Pico text editor Basic HTMLBasic HTML

Set up your i5 webpageSet up your i5 webpage


The InternetThe Internet1969, ARPANet1969, ARPANet

After WAR WAR II and during Cold war, US government After WAR WAR II and during Cold war, US government was interested in science and technology research to improve was interested in science and technology research to improve radar signals and communicationsradar signals and communications

The Internet was founded, by a US military network called The Internet was founded, by a US military network called ARPANetARPANet (Advanced Research Projects Agency network)(Advanced Research Projects Agency network)

ARPANet formed in ARPANet formed in 19691969 to research networking. to research networking. They documented the They documented the Internet protocolsInternet protocols Email was developedEmail was developed Networked 4 computers together Government also funded universities for Networked 4 computers together Government also funded universities for

research: research: MIT Multimedia lab was founded, NASA was also formed to distribute funds to MIT Multimedia lab was founded, NASA was also formed to distribute funds to

universities and other centersuniversities and other centers


ARPANet improved Networking ARPANet improved Networking protocolsprotocols

and applicationsand applications

TCP/IPTCP/IP (Transmission Control Protocol/Internet Protocol)(Transmission Control Protocol/Internet Protocol) is is the protocol that is used to connect or the protocol that is used to connect or network computers togethernetwork computers together

Internet Applications especially email, Internet Applications especially email, FTP FTP (File Transfer Protocol)(File Transfer Protocol) and and Telnet Telnet for for transferring files and exchanging messages transferring files and exchanging messages over the Internetover the Internet

In the 1970’s, In the 1970’s, UnixUnix Operating system was Operating system was developed by Berkeley and AT&T. developed by Berkeley and AT&T.

Most of the Internet protocols were Most of the Internet protocols were developed and used on UNIX platformdeveloped and used on UNIX platform

More people were convinced that it was More people were convinced that it was going to be a success. going to be a success.


What is the InternetWhat is the Internet So what is "the Internet"?

The Internet is a gigantic collection of millions of computers, all linked together on a computer network.

The network allows all of the computers to communicate with one another. A home computer may be linked to the Internet using a phone-line modem, DSL

or cable modem that talks to an Internet service provider (ISP).

A computer in a business or university will usually have a network interface card (NIC) that directly connects it to a local area network (LAN) inside the business. The business can then connect its LAN to an ISP using a high-speed phone line like a T1 line.

A T1 line can handle approximately 1.5 million bits per second, while a normal phone line using a modem can typically handle 30,000 to 50,000 bits per second.

ISPs then connect to larger ISPs, and the largest ISPs maintain fiber-optic "backbones" for an entire nation or region.

Backbones around the world are connected through fiber-optic lines, undersea cables or satellite links

In this way, every computer on the Internet is connected to every other computer on the Internet.


1980, PC’s & Networking1980, PC’s & Networking In the 1980's, In the 1980's, personal computerspersonal computers became a common became a common

fixture in homes and offices supplying business with fixture in homes and offices supplying business with computers computers IBM and GatesIBM and Gates Apple computersApple computers

SoftwareSoftware grew into one of the biggest industries in grew into one of the biggest industries in less than a decade. less than a decade.

NetworkingNetworking became a profitable business for became a profitable business for engineers previously restricted to networking engineers previously restricted to networking mainframesmainframes


The Internet opened new doors in 1980's and new company emerged and The Internet opened new doors in 1980's and new company emerged and became successful.became successful.

Bob MetcalfeBob Metcalfe, an engineer from ARPANet, developed , an engineer from ARPANet, developed 3Com3Com. This allowed . This allowed personal computers to be networked and connected to the Internet. Still used personal computers to be networked and connected to the Internet. Still used today and very successful. today and very successful.

Four people from Stanford and BerkeleyFour people from Stanford and Berkeley established established “SUN”.“SUN”. Sun machines are Sun machines are work stations which can crunch numbers faster than mainframes and cheaper. work stations which can crunch numbers faster than mainframes and cheaper.

An engineer from Utah An engineer from Utah created created NovelNovel where operating systems can be where operating systems can be connected together to exchange documentsconnected together to exchange documents

A A couple from Stanfordcouple from Stanford, improved ways of connecting computers together , improved ways of connecting computers together forming “forming “CISCOCISCO” and famous for their routers” and famous for their routers

New company’s emergedNew company’s emerged

Foundation for Super Information HighwayFoundation for Super Information Highway


1989-19901989-1990Transfer of Internet from GovernmentTransfer of Internet from Government

At the beginning of 1989 over 80,000 At the beginning of 1989 over 80,000 host computers were connected to what host computers were connected to what was now called the Internetwas now called the Internet

The US Government officially transferred The US Government officially transferred the governess of the Internet to the the governess of the Internet to the National Science Foundation (NSF)National Science Foundation (NSF)

NSFNSF took control of managing the back took control of managing the back bone of the internet and was then called bone of the internet and was then called the “the “NSFNetNSFNet””

In 1995, the NSF turned control of the In 1995, the NSF turned control of the Internet to a Internet to a consortium.consortium.


World Wide Web (WWW) World Wide Web (WWW) Invented by Tim Berners-Lee Invented by Tim Berners-Lee

CERN, 1989-1990CERN, 1989-1990 Tim invented HTML, the first server and the first web browser Tim invented HTML, the first server and the first web browser

(Lynx)(Lynx) The The World Wide WebWorld Wide Web (now referred to as the (now referred to as the webweb or or WWWWWW) ) The web is one of the Internet services and allows for the The web is one of the Internet services and allows for the

exchanging of documents (video, text, music, images) over the exchanging of documents (video, text, music, images) over the internet using internet using HTTP (Hyper Text Transfer Protocol) protocolHTTP (Hyper Text Transfer Protocol) protocol

Using the Web, you have access to millions of pages of Using the Web, you have access to millions of pages of information. information.

The pages on the web are connected together by The pages on the web are connected together by

hypertext or linkshypertext or links Web pages are written in HTML, Hyper Text Web pages are written in HTML, Hyper Text

Markup languageMarkup language


Web BrowsersWeb BrowsersMosaic, Netscape, Mosaic, Netscape,

and Internet Explorer and Internet Explorer

(I.E.)(I.E.) A A browserbrowser is an is an application program or software application program or software that that

request documents from computers connected to the request documents from computers connected to the internet (servers) around the world and then displays the internet (servers) around the world and then displays the information in the browser window. The browser displays information in the browser window. The browser displays the information according to HTML instructions.the information according to HTML instructions.

LynxLynx, is the first web browser. It is a TEXT based browser , is the first web browser. It is a TEXT based browser invented by Tim Lee.invented by Tim Lee.

MosaicMosaic is the first graphical Web browser which allowed is the first graphical Web browser which allowed you to view you to view multimedia files (music, video, and graphical multimedia files (music, video, and graphical files)files) on the Web. Mosaic was invented by on the Web. Mosaic was invented by Marc AndersonMarc Anderson, a , a student at University of Illinois in student at University of Illinois in 19921992

NetscapeNetscape in in 1994 by Marc Anderson1994 by Marc Anderson Internet Explorer (I. E.)Internet Explorer (I. E.) in in 1995 by Microsoft1995 by Microsoft after congress after congress

passed bill to open web for commercepassed bill to open web for commerce


How web worksHow web worksYour browser formed a connection to a Web server, requested a page and received it. Here are the details:

The browser broke the URL into three parts: n 1. The protocol ("http") n 2. The server name ("www.cnn.com") n 3. The file name (”index.htm")

• The browser communicated with a name server to translate the server name "www.cnn.com" into an IP Address, which it uses to connect to the server machine.

IP Addresses To keep all of the machines on the Internet straight, each machine is assigned a unique address called an IP address. IP stands for Internet protocol, and these addresses are 32-bit numbers normally expressed as four "octets" in a

"dotted decimal number." A typical IP address looks like this:

WEB.nyu.edu has address 128.122.108.74WEB.nyu.edu has address 128.122.108.74 The four numbers in an IP address are called octets because they can have values

between 0 and 255 (28 possibilities per octet )• The browser then formed a connection to the server at that IP address on port 80.

• (the default extension for web. Each internet service has a specify port ) • Following the HTTP protocol, the browser sent a GET request to the server, asking for the file

"http://computer.cnn.com/index.htm." • The server then sent the HTML text for the Web page to the browser. * The browser read the HTML tags and formatted the page onto your screen.


Your computer is running a web browser

Computer is running a web server

Your browser requests a webpage

Server sends back the page or document


Web Servers and Web Servers and browsersbrowsers

ServersServers are software that allows a computer are software that allows a computer connected to the Internet to store information connected to the Internet to store information or documents (text, images, video, sound.. or documents (text, images, video, sound.. Etc..) and then delivers or sends back these Etc..) and then delivers or sends back these documents to the browserdocuments to the browser

Browser is the clientBrowser is the client: the browser requests : the browser requests the documents and the server deliver the the documents and the server deliver the documents back to browserdocuments back to browser

Both the browser and the server understand Both the browser and the server understand the the HTTPHTTP ( (HyperText Transfer ProtocolHyperText Transfer Protocol) ) language and that’s how they communicate language and that’s how they communicate togethertogether


Java and JavaScript - 1995Java and JavaScript - 1995Interactivity on the web vs. static HTML Interactivity on the web vs. static HTML

documentsdocuments

JavaJava is a very powerful programming is a very powerful programming language for the web invented by language for the web invented by SUNSUN Allows for real-time interactivity (chat, Allows for real-time interactivity (chat,

videoconferencing)videoconferencing)

JavaScript:JavaScript: is a language invented by is a language invented by Netscape to use with HTML for Netscape to use with HTML for Dynamic and interactive web pages Dynamic and interactive web pages


Internet ServicesInternet Services& &

ProtocolsProtocols


Internet ServicesInternet ServicesAre applications, software that run on Are applications, software that run on the Internet using different protocolsthe Internet using different protocols

World Wide Web (WWW)World Wide Web (WWW) or the Web which or the Web which exchanges documents using HTTP protocolsexchanges documents using HTTP protocols

Ws_FTP:Ws_FTP: Download and upload files on the Download and upload files on the Internet to and from you computer using FTP (File Internet to and from you computer using FTP (File transfer protocol). transfer protocol).

TenetTenet EmailEmail ChatChat


Internet ProtocolsInternet Protocols

PPPPPP: Point to Point Protocol, used to connect a Personal : Point to Point Protocol, used to connect a Personal computer to the Internet via modemcomputer to the Internet via modem

SMTPSMTP: Simple Mail Transfer Protocol, used to send (route) e-: Simple Mail Transfer Protocol, used to send (route) e-mail over the Internetmail over the Internet

FTPFTP: File transfer protocol. Download and upload files on the : File transfer protocol. Download and upload files on the Internet to and from you computerInternet to and from you computer

HTTPHTTP: Hypertext Transfer Protocol are: Hypertext Transfer Protocol areset of rules for exchanging files (text, graphic images, sound, set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web.video, and other multimedia files) on the World Wide Web.


How does the web work?How does the web work?

Documents can be exchanged over the web using Documents can be exchanged over the web using HTTP protocolHTTP protocol Web Web browsers allows you to request documentsbrowsers allows you to request documents and then and then display display

them for you using HTMLthem for you using HTML Web Servers allows you to store documents and then send them Web Servers allows you to store documents and then send them

to browsers upon requestto browsers upon request Both servers and browser understands and communicate Both servers and browser understands and communicate HTTP HTTP

protocolprotocol or language or language The web uses an addressing scheme that every computer on the The web uses an addressing scheme that every computer on the

Net understandsNet understands


Domain name (nyu.edu)Domain name (nyu.edu)•Domain names are the next level of Internet addressing. Just like street names is followed by city and state.

•Domain names create single identity for a series of computers associated with a company or an institution

•A domain name locates an organization or other entity on the Internet. It is usually the organization or company’s trademark.Every company or organization has to apply for its unique domain name and it has to be approved by ICANN (International NON-Profit group that administers the domain-name system) or other private companies such as register.comFor example, nyu.edu is the domain name or the NYU website Lets look at how to obtain a domain name:

http://www.networksolutions.com to see if domain is available


DNS: Domain Name DNS: Domain Name SystemSystem

A centralized database includes a A centralized database includes a complete lists of domain names and IP complete lists of domain names and IP addresses which are distributed addresses which are distributed throughout the Internet in a hierarchy of throughout the Internet in a hierarchy of authority.authority.

There is probably a DNS server within There is probably a DNS server within close geographic proximity to your access close geographic proximity to your access provider that maps the domain names in provider that maps the domain names in your Internet requests or forwards them your Internet requests or forwards them to other servers in the Internet. to other servers in the Internet.


Who controls the Who controls the Internet?Internet? Not one person, company or government owns the Not one person, company or government owns the

InternetInternet Its truly collaborative, collective enterpriseIts truly collaborative, collective enterprise There are organizations that have influence and There are organizations that have influence and

together form a collective body to guide the Internet together form a collective body to guide the Internet and the web:and the web: The World Wide Web Consortium (W3C):The World Wide Web Consortium (W3C): sets specification sets specification

for HTML and the webfor HTML and the web The Internet Engineering Task Force (IETF)The Internet Engineering Task Force (IETF) focuses on focuses on

the evolution of the Internet and making sure it runs the evolution of the Internet and making sure it runs smoothsmooth

The Internet Architecture Board (IAB): responsible for The Internet Architecture Board (IAB): responsible for defining the backbone of the Internetdefining the backbone of the Internet

The Internet Society (ISOC):The Internet Society (ISOC): made up of organizations, made up of organizations, governments, non profit, communities, Academics, governments, non profit, communities, Academics, professionals. The group comments on Internet polices, professionals. The group comments on Internet polices, politics, and oversee other boards such as IETFpolitics, and oversee other boards such as IETF

The Internet Assigned Authority (IANA) and the Internet The Internet Assigned Authority (IANA) and the Internet Network Information Center (InterNIC).Network Information Center (InterNIC). This group is This group is responsible for ip and domain name addressingresponsible for ip and domain name addressing


Who controls the backbone of the Who controls the backbone of the Internet?Internet?

Regional and long-distance phone Regional and long-distance phone companies, backbone ISP’s, cable and companies, backbone ISP’s, cable and satellite companies, and U.S satellite companies, and U.S government contribute in significant government contribute in significant ways to the telecommunication ways to the telecommunication infrastructure that supports the Internetinfrastructure that supports the Internet

Companies like Sprint, MCI and AT&T Companies like Sprint, MCI and AT&T make lots of money by leasing access to make lots of money by leasing access to the Internetthe Internet

Lets look at MCI global networkLets look at MCI global network http://global.mci.com/about/network/maps/?flash=1&theme=http://global.mci.com/about/network/maps/?flash=1&theme=


Bandwidth: speed in which data travel on the netBandwidth: speed in which data travel on the net Low speed (PPP or modem) : Modem connections 28,000k, 56,000K is the fastestLow speed (PPP or modem) : Modem connections 28,000k, 56,000K is the fastest

High-speed connection to the InternetHigh-speed connection to the Internet ISDN, Cable Modem, DSL, T1, T3ISDN, Cable Modem, DSL, T1, T3

ISDN (Integrated Service Digital Network): ISDN (Integrated Service Digital Network): Digital transmission over telephone lines. Its speed is up to Digital transmission over telephone lines. Its speed is up to 128Kbps. Available from Telephone company.128Kbps. Available from Telephone company.

Cable Modem: Cable Modem: connects you PC to a local cable TV line and receives data at connects you PC to a local cable TV line and receives data at 1.5-10 Mbps1.5-10 Mbps (Millions bits per (Millions bits per second). RCN Cablessecond). RCN Cables

DSL(Digital subscriber line): DSL(Digital subscriber line): Digital transmission of data over telephone line. Available from Telephone Digital transmission of data over telephone line. Available from Telephone company. company.

Speed is about Speed is about 1-10 Mbps. 1-10 Mbps. T1: The T-carrier system T1: The T-carrier system transmits at transmits at 1- 3 Mbps 1- 3 Mbps. .

Used by ISP’sUsed by ISP’s T2: The T-carrier system T2: The T-carrier system transmits at transmits at 6.3 Mbps6.3 Mbps. .

Used by ISP’sUsed by ISP’s T3: Also used by ISP’s. 44 MbpsT3: Also used by ISP’s. 44 Mbps T4: used by ISP’s. 274 MbpsT4: used by ISP’s. 274 Mbps


Internet TermsInternet Terms

URL- (Uniform Resource Locator) is URL- (Uniform Resource Locator) is the address of a the address of a filefile or a or a web pageweb page on the on the

webweb An example of a URL :An example of a URL : http://www.nyu.edu/http://www.nyu.edu/


Internet TermsInternet Terms

Router:Router: A piece of hardware that is configures A piece of hardware that is configures with software to route data from a LAN to a with software to route data from a LAN to a phone line- long distancephone line- long distance

Routers act as traffic cops, allowing only Routers act as traffic cops, allowing only authorized machines to transmit/receive data authorized machines to transmit/receive data into a local area network. into a local area network. It handles security It handles security issuesissues


On the Internet, the term "host" means any computer that has full two-way access to other computers on the Internet. A host has a specific "local or host number" that, together with the network number, forms its unique IP address. www.nyu.edu is the host for NYU

HostHost


HTMLHTML

•HTML (Hypertext Markup Language) is the set of "markup" symbols or codes inserted in a file intended for display on a World Wide Web browser.

•The markup tells the Web browser how to display a Web page's text, images, sound and video files for the user.

•The individual markup codes are referred to as elements (but many people also refer to them as tag).


Lets review information on Lets review information on setting up your i5 account web setting up your i5 account web

pagepage

Review secure applications needed to Review secure applications needed to connectconnect

Review UNIX commandsReview UNIX commands http://cs.nyu.edu/courses/fall04/V22.0380-002/http://cs.nyu.edu/courses/fall04/V22.0380-002/

•


Internet backboneInternet backbone

The backbone of the InternetThe backbone of the Internet is owned is owned by major Internet Service Providers by major Internet Service Providers (ISP’s)(ISP’s) such as such as AT&T, MCI, SPRINT, AT&T, MCI, SPRINT, UUNet, GTEUUNet, GTE

The Internet backbone allows for The Internet backbone allows for information to be exchanged and information to be exchanged and applications to run such as Telnet, FTP, applications to run such as Telnet, FTP, web, mail using different protocolsweb, mail using different protocols

internet and the web lecture

Documents

transfer of internet

internet usin

connector network computers

course web site

web development

web history

personal computers

computers ibm