Welcome! Web Development and Programming

1. Welcome!Web Developmentand Programming Professor: Sana’ Odeh odeh@cs.nyu.edu Course Introduction

2. Getting Help • If you need help, you always have three options: • Office Hours: • Class Tutor: available by email and at the lab at 14 Washington Place (6 hours a week) to help out with any homework questions. Course Introduction

3. 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 Course Introduction

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

5. Foundations of the Web Course Introduction

6. 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 Course Introduction

7. 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 Course Introduction

8. 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 1970’s, Unix Operating system was developed by Berkeley and AT&T. • Most of the Internet protocols were developed and used on UNIX platform • More people were convinced that it was going to be a success. Course Introduction

9. 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. Course Introduction

10. 1980, PC’s & 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 Course Introduction

11. New company’s 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 Course Introduction

12. 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. Course Introduction

13. 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 Course Introduction

14. 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. • Mosaicis 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 Course Introduction

15. 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. • * The browser read the HTML tags and formatted the page onto your screen. Course Introduction

16. 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 Course Introduction

17. 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 that’s how they communicate together Course Introduction

18. 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 Course Introduction

19. Internet Services& Protocols Course Introduction

20. 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 Course Introduction

21. 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. Course Introduction

22. 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 Course Introduction

23. 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.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 Course Introduction

24. 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. Course Introduction

25. 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 Course Introduction

26. Who controls the backbone of the Internet? • Regional and long-distance phone companies, backbone ISP’s, 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 AT&T make lots of money by leasing access to the Internet • Lets look at MCI global network • http://global.mci.com/about/network/maps/?flash=1&theme= Course Introduction

27. 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 ISP’s • T2: The T-carrier system transmits at 6.3 Mbps. Used by ISP’s • T3: Also used by ISP’s. 44 Mbps • T4: used by ISP’s. 274 Mbps Course Introduction

28. 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/ Course Introduction

29. 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 Course Introduction

30. 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 Course Introduction

31. 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). Course Introduction

32. 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/ Course Introduction

33. Internet backbone • The backbone of the Internet is owned by major Internet Service Providers (ISP’s) such as AT&T, 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 Course Introduction