The Internet and HTML. Jen Golbeck College of Information Studies University of Maryland

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1 The Internet and HTML Jen Golbeck College of Information Studies University of Maryland 1

2 A Short History of the Internet 1969: Origins in government research Advanced Research Projects Agency (ARPAnet) 1983: Design adopted by other agencies Expansion from educational institutions to corporations 1991: World Wide Web added pointand-click capabilities 2

3 The Internet Global collection of public networks Private networks are often called intranets Each organization maintains its own network Use of shared protocols TCP/IP (Transmission Control Protocol/Internet Protocol): basis for communication DNS (Domain Name Service): basis for naming hosts HTTP (HyperText Transfer Protocol): World Wide Web 3

4 Packet Routing (TCP/IP) (Much simplified) Routing table for Destination *.* 18.1.*.* 4.*.*.* Next Hop /

5 Addresses and Domain Names Every computer has an IP address E.g Hard to remember, and hard wired Domain names are short cuts to IP addresses umd.edu, facebook.com, etc 5

6 Domain Name Service (DNS) Domain names improve usability Easier to remember than numeric IP addresses DNS coverts between names and numbers Written like a postal address: specific-to-general Each name server knows one level of names Top level name server knows.edu,.com,.mil,.edu name server knows umd, umbc, stanford,.umd.edu name server knows wam, glue, ttclass,.wam.umd.edu name server knows rac1, rac2, 6

7 7 Domain Names Unsponsored.biz.com.edu.gov.info.int.mil.name.net.org Sponsored.aero.asia.cat.coop.jobs.mobi.museum.pro.tel.travel Infrastructure:.arpa.root Proposed.berlin.bzh.cym.gal.geo.kid.kids.lat.mail.nyc.post.sco.web.xxx Deleted/retired:.nato Reserved.example.invalid.localhost.test

8 If you want one 8 You need a web host Company to host your web pages Alternatively, you can do it yourself, but it requires a lot of infrastructure (and permissions) you don t have Cost ranges from $5/month (e.g. ) and up depending on services You register for a domain name and point it to the host Cost is about $35/year (less if you buy for multiple years)

9 The Web Not the same thing as the Internet Internet is the network of computers that sends information around ( , web pages, chat, skype, file transfers, etc) The web is a layer on top of the internet that sends files in a certain way (using HTTP) now 9

10 Foundations of the Web TCP/IP DNS HTTP 10

11 Standards No one owns the web or the internet Platform and software independent - it should work the same everywhere W3C - World Wide Web Consortium A group of people (universities, businesses, governments, etc) who decide by committee what the web will be and how it changes Some people modify standards BAD! E.g. a web page that only works in Internet Explorer 11

12 HTML and XHTML HTML based on meta-language SGML SGML has lots of freedom, but that makes it harder to parse XHTML is based on XML Almost identical to HTML, except for a few stricter rules There are billions of web pages that are valid HTML but not valid XHTML - Thus, HTML will keep being supported pretty much forever 12

13 Why Code HTML by Hand? 13 The only way to learn is by doing WSIWYG editors Often generate unreadable code Ties you down to that particular editor Cannot help you connect to backend databases Hand coding HTML allows you to have finergrained control HTML is demonstrative of other important concepts: Structured documents Metadata

14 Today s Tutorial Your first HTML page Uploading your page to the Web server via FTP 14

15 HTML Basics 15 Tags <body> <b> <table> End Tags </body> </b> </table> Tag names are not case sensitive in HTML, are case sensitive and all lower case in XHTML

16 HTML Basics II 16 Every tag has an end tag (with a few exceptions) In HTML, some tags don t have an end tag E.g. the tag for putting an image on the page <img> or adding a line break <br> In XHTML, all tags need end tags. However, in some cases it doesn t make sense Short hand for starting and ending a tag all at once <br /> Note there is a space and then a slash at the end

17 HTML Basics III Attributes Add features to a tag <body bgcolor= red > Structure Attribute name = attribute value E.g. bgolor=red Values must be in quotes in XHTML Quotes are optional in HTML unless there is a space in the value. Then quotes are required Single or double quotes are fine 17

18 HTML Basics IV Learning HTML is basically just learning all the tag names and attributes Becoming a web designer takes a lot more than that Practice Practice Practice 18

19 Hello World HTML This is the header <html> <head> <title>hello World!</title> </head> <body> <p>hello world! This is my first webpage!</p> </body> </html> This is the actual content of the HTML document 19

20 Uploading Your Page Connect to terpconnect.umd.edu Go up one level in the directories Change directory to pub Upload files We will do this in detail in the next session 20

21 Tips Edit files on your own machine, upload when you re happy Save early, save often, just save! Reload browser 21

22 A little bonus on the history of the internet 22

23 How did the Internet come to be? It started as a research project to experiment with connecting computers together with packet switched networks. It was developed with funding and leadership of the Defense Department s Advanced Research Projects Agency (ARPA). 23

24 Who invented the Internet? Leonard Kleinrock who did early work in packet switching Vint Cerf and Robert Kahn who defined the "Internet Protocol" (IP) and participated in the development of TCP 24

25 : Connect Computers? 1958 After USSR launches Sputnik, first artificial earth satellite, US forms the Advanced Research Projects Agency (ARPA), the following year, within the Department of Defense (DoD) to establish US lead in science and technology applicable to the military 1961 First published work on packet switching ( Information Flow in Large Communication Nets, Leonard Kleinrock, MIT graduate student) 1964 other independent work in packet switching at RAND Institute and National Physics Laboratory in England 25

26 : Connect Computers? Funded Lawrence Roberts (colleague of Kleinrock from MIT) publishes overall plan for an ARPAnet, a proposed packet switch network 1968 ARPA awards contracts for four nodes in ARPANET to UCLA (Network Measurement), Stanford Research Institute (Network Information Center), UCSB (Interactive Mathematics) and U Utah (Graphics); BBN gets contract to build the IMP switches

27 1969: First Connections 4/7/1969 First RFC ( Host Software by Steve Crocker) basis for the Network Control Protocol(NCP) 9/2/1969 Leonard Kleinrock s computer at UCLA becomes first node on the ARPANET 10/29/1969 First packets sent; Charlie Kline attempts use of remote login from UCLA to SRI; system crashes as G in entered 27

28 : So what do we do with it? Vint Cerf, graduate student in Kleinrock s lab, works on application level protocols for the ARPANET (file transfer and Telnet protocols) Ray Tomlinson of BBN writes application; derived from two existing: an intramachine program (SENDMSG) and an experimental file transfer program (CPYNET) 28

29 Networks Growing First cross-country link installed by AT&T between UCLA and BBN at 56kbps Other networks: ALOHAnet (microwave network in Hawaii), Telenet (commercial, BBN), Transpac (France) 1973 Ethernet was designed in 1973 by Bob Metcalfe at Xerox Palo Alto Research Center (PARC) How do we connect these networks together? 29

30 : Protocol Development Robert Kahn and Vint Cerf develop protocols to connect networks without any knowledge of the topology or specific characteristics of the underlying nets 1972 Robert Kahn gives first public demonstration of ARPAnet (now 15 nodes) at International Conference on Computer Communication 30

31 : Development of TCP/IP 1974 First full draft of TCP produced November First three-network TCP/IP based interconnection demonstrated linking SATNET, PRNET and ARPANET in a path leading from Menlo Park, CA to Univ. College London and back to USC/ISI (Marina del Ray, CA) 1978 TCP split into TCP and IP 31

32 : Base Protocols In Place 1981 Term Internet coined to mean collection of interconnected networks 1982 ISO releases OSI seven layer model; actual protocols die but model is influential 1/1/1983 Original ARPANET NCP was banned from the ARPANET and TCP/IP was required 1984 Cisco Systems founded 32

33 : Not Just a Research Project Anymore 1984 Domain Name System introduced; hosts (200 hosts by end of 1970s; over by end of 1980s) 1986 NSFNET created to provide access to 5 super computer centers (NSFNET backbone speeds 56 Kbps) 1983 ARPANET split into ARPANET and MILNET; MILNET to carry defense related traffic 33

34 : Growing Pains? Nodes on Internet began to double every year November 1988 Internet worm affecting about 10% of the computers on the Internet Internet Assigned Numbers Authority (IANA) established in December with Jon Postel as its Director. Postel was also the RFC Editor and US Domain registrar for many years 34

35 : WWW Explosion ARPANET ceases to exist 1990 Tim Berners-Lee develops hypertext system with initial versions of HTML and HTTP and first GUI web browser called WorldWideWeb 1993 Mosaic, a GUI web browser, written by Marc Andreessen and Eric Bina at NCSA takes world by storm (showed in-line images and was easy to install); WWW proliferates at a 341,634% annual growth rate of service traffic

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