Welcome Web Development and Programming V22'0380

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Welcome!Web Developmentand Programming
V22.0380

• Professor Sana Odeh
• odeh_at_cs.nyu.edu

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Getting Help

• If you need help, you always have three options
• Office Hours everyMON. Wed, 130 - 300 pm
• Office 418, Warren Weaver Hall
• Class Tutor available by email and at the lab
  at 14 Washington Place (6 hours a week) to help
  out with any homework questions.

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Course Web Site

• The Course Web Site is available at
• http//cs.nyu.edu/courses/fall04/V22.0380-002/
• Lets check it out

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I5 Accounts

• If you are registered for this course, you
  already have an i5 account.
• Your i5.nyu.edu system uses NYUHome NetID as
  their username, and their central NYU single
  sign-on password to log in.
• You need an active NYUHome account to login to
  your i5 account.
• To set, or change this password, go to
  http//start.nyu.edu

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Lecture Notes

• Most lecture notes will be available as Power
  Point Slides.
• You can easily download these from the course web
  site (more later)

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Foundations of the Web
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Outline

• Foundation of the Internet and the Web
• History of the Internet and the web
• Internet Services
• Internet protocols
• Internet terms
• Review of Unix commands
• Review of Pico text editor
• Basic HTML
• Set up your i5 webpage

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The Internet1969, ARPANet

• After WAR WAR II and during Cold war, US
  government was interested in science and
  technology research to improve radar signals and
  communications
• The Internet was founded, by a US military
  network called ARPANet (Advanced Research
  Projects Agency network)
• ARPANet formed in 1969 to research networking.
• They documented the Internet protocols
• Email was developed
• Networked 4 computers together Government also
  funded universities for research
• MIT Multimedia lab was founded, NASA was also
  formed to distribute funds to universities and
  other centers

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ARPANet improved Networking protocolsand
applications

• TCP/IP (Transmission Control Protocol/Internet
  Protocol) is the protocol that is used to connect
  or network computers together
• Internet Applications especially email, FTP
  (File Transfer Protocol) and Telnet for
  transferring files and exchanging messages over
  the Internet
• In the 1970s, Unix Operating system was
  developed by Berkeley and ATT.
• Most of the Internet protocols were developed and
  used on UNIX platform
• More people were convinced that it was going to
  be a success.

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What 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.

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1980, PCs Networking

• In the 1980's, personal computers became a common
  fixture in homes and offices supplying business
  with computers
• IBM and Gates
• Apple computers
• Software grew into one of the biggest industries
  in less than a decade.
• Networking became a profitable business for
  engineers previously restricted to networking
  mainframes

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• New companys emerged
• Foundation for Super Information Highway

• The Internet opened new doors in 1980's and new
  company emerged and became successful.
• Bob Metcalfe, an engineer from ARPANet, developed
  3Com. This allowed personal computers to be
  networked and connected to the Internet. Still
  used today and very successful.
• Four people from Stanford and Berkeley
  established SUN. Sun machines are work stations
  which can crunch numbers faster than mainframes
  and cheaper.
• An engineer from Utah created Novel where
  operating systems can be connected together to
  exchange documents
• A couple from Stanford, improved ways of
  connecting computers together forming CISCO and
  famous for their routers

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1989-1990Transfer of Internet from Government

• At the beginning of 1989 over 80,000 host
  computers were connected to what was now called
  the Internet
• The US Government officially transferred the
  governess of the Internet to the National Science
  Foundation (NSF)
• NSF took control of managing the back bone of the
  internet and was then called the NSFNet
• In 1995, the NSF turned control of the Internet
  to a consortium.

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World Wide Web (WWW) Invented by Tim Berners-Lee
CERN, 1989-1990

• Tim invented HTML, the first server and the first
  web browser (Lynx)
• The World Wide Web (now referred to as the web or
  WWW)
• The web is one of the Internet services and
  allows for the exchanging of documents (video,
  text, music, images) over the internet using HTTP
  (Hyper Text Transfer Protocol) protocol
• Using the Web, you have access to millions of
  pages of information.
• The pages on the web are connected together by
  hypertext or links
• Web pages are written in HTML, Hyper Text Markup
  language

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Web BrowsersMosaic, Netscape, and Internet
Explorer (I.E.)

• A browser is an application program or software
  that request documents from computers connected
  to the internet (servers) around the world and
  then displays the information in the browser
  window. The browser displays the information
  according to HTML instructions.
• Lynx, is the first web browser. It is a TEXT
  based browser invented by Tim Lee.
• Mosaic is the first graphical Web browser which
  allowed you to view multimedia files (music,
  video, and graphical files) on the Web. Mosaic
  was invented by Marc Anderson, a student at
  University of Illinois in 1992
• Netscape in 1994 by Marc Anderson
• Internet Explorer (I. E.) in 1995 by Microsoft
  after congress passed bill to open web for
  commerce

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How web works

• Your 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
• 1. The protocol ("http")
• 2. The server name ("www.cnn.com")
• 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 128.122.108.74
• 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.

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Computer is running a web server
Your computer is running a web browser
Your browser requests a webpage
Server sends back the page or document
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Web Servers and browsers

• Servers are software that allows a computer
  connected to the Internet to store information or
  documents (text, images, video, sound.. Etc..)
  and then delivers or sends back these documents
  to the browser
• Browser is the client the browser requests the
  documents and the server deliver the documents
  back to browser
• Both the browser and the server understand the
  HTTP (HyperText Transfer Protocol) language and
  thats how they communicate together

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

• Java is a very powerful programming language for
  the web invented by SUN
• Allows for real-time interactivity (chat,
  videoconferencing)
• JavaScript is a language invented by Netscape to
  use with HTML for Dynamic and interactive web
  pages

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Internet Services Protocols
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Internet ServicesAre applications, software that
run on the Internet using different protocols

• World Wide Web (WWW) or the Web which exchanges
  documents using HTTP protocols
• Ws_FTP Download and upload files on the Internet
  to and from you computer using FTP (File transfer
  protocol).
• Tenet
• Email
• Chat

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Internet Protocols

• PPP Point to Point Protocol, used to connect a
  Personal computer to the Internet via modem
• SMTP Simple Mail Transfer Protocol, used to send
  (route) e-mail over the Internet
• FTP File transfer protocol. Download and upload
  files on the Internet to and from you computer
• HTTP Hypertext Transfer Protocol are
• set of rules for exchanging files (text, graphic
  images, sound, video, and other multimedia files)
  on the World Wide Web.

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How does the web work?

• Documents can be exchanged over the web using
  HTTP protocol
• Web browsers allows you to request documents and
  then display them for you using HTML
• Web Servers allows you to store documents and
  then send them to browsers upon request
• Both servers and browser understands and
  communicate HTTP protocol or language
• The web uses an addressing scheme that every
  computer on the Net understands

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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 companys 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.com
• For 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

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DNS Domain Name System

• A centralized database includes a complete lists
  of domain names and IP addresses which are
  distributed throughout the Internet in a
  hierarchy of authority.
• There is probably a DNS server within close
  geographic proximity to your access provider that
  maps the domain names in your Internet requests
  or forwards them to other servers in the
  Internet.

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Who controls the Internet?

• Not one person, company or government owns the
  Internet
• Its truly collaborative, collective enterprise
• There are organizations that have influence and
  together form a collective body to guide the
  Internet and the web
• The World Wide Web Consortium (W3C) sets
  specification for HTML and the web
• The Internet Engineering Task Force (IETF)
  focuses on the evolution of the Internet and
  making sure it runs smooth
• The Internet Architecture Board (IAB)
  responsible for defining the backbone of the
  Internet
• The Internet Society (ISOC) made up of
  organizations, governments, non profit,
  communities, Academics, professionals. The group
  comments on Internet polices, politics, and
  oversee other boards such as IETF
• The Internet Assigned Authority (IANA) and the
  Internet Network Information Center (InterNIC).
  This group is responsible for ip and domain name
  addressing

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Who controls the backbone of the Internet?

• Regional and long-distance phone companies,
  backbone ISPs, cable and satellite companies,
  and U.S government contribute in significant ways
  to the telecommunication infrastructure that
  supports the Internet
• Companies like Sprint, MCI and ATT make lots of
  money by leasing access to the Internet
• Lets look at MCI global network
• http//global.mci.com/about/network/maps/?flash1
  theme

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Bandwidth speed in which data travel on the net

• Low speed (PPP or modem) Modem connections
  28,000k, 56,000K is the fastest
• High-speed connection to the Internet
• ISDN, Cable Modem, DSL, T1, T3
• ISDN (Integrated Service Digital Network)
  Digital transmission over telephone lines. Its
  speed is up to 128Kbps. Available from Telephone
  company.
• Cable Modem connects you PC to a local cable TV
  line and receives data at 1.5-10 Mbps (Millions
  bits per second). RCN Cables
• DSL(Digital subscriber line) Digital
  transmission of data over telephone line.
  Available from Telephone company.
• Speed is about 1-10 Mbps.
• T1 The T-carrier system transmits at 1- 3 Mbps.
  
• Used by ISPs
• T2 The T-carrier system transmits at 6.3 Mbps.
• Used by ISPs
• T3 Also used by ISPs. 44 Mbps
• T4 used by ISPs. 274 Mbps

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Internet Terms

• URL- (Uniform Resource Locator) is
• the address of a file or a web page on the web
• An example of a URL
• http//www.nyu.edu/

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Internet Terms

• Router A piece of hardware that is configures
  with software to route data from a LAN to a phone
  line- long distance
• Routers act as traffic cops, allowing only
  authorized machines to transmit/receive data into
  a local area network. It handles security issues

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Host

• 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

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HTML

• 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).

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Lets review information on setting up your i5
account web page

• Review secure applications needed to connect
• Review UNIX commands
• http//cs.nyu.edu/courses/fall04/V22.0380-002/

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Internet backbone

• The backbone of the Internet is owned by major
  Internet Service Providers (ISPs) such as ATT,
  MCI, SPRINT, UUNet, GTE
• The Internet backbone allows for information to
  be exchanged and applications to run such as
  Telnet, FTP, web, mail using different protocols