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Chicago

Chicago. Boston. CNY. Seattle. NYC. Denver. SF. ARPANET ‘60s CSNET NSFNET ANSNET. LA. Houston. WAN (Wide Area Network ). , but not really. Local Area Network Emerged, 1970’s. Chicago. Boston. Seattle. NYC. Denver. SF. LA. Houston. WAN  Backbone Network (early ‘80s).

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Chicago

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  1. Chicago Boston CNY Seattle NYC Denver SF ARPANET ‘60s CSNET NSFNET ANSNET LA Houston WAN (Wide Area Network ) , but not really

  2. Local Area Network Emerged, 1970’s Chicago Boston Seattle NYC Denver SF LA Houston

  3. WAN  Backbone Network (early ‘80s) Chicago Boston CNY Seattle NYC Denver SF ARPANET CSNET NSFNET ANSNET LA Houston

  4. SU Internet and Routers Chicago Boston CNY Seattle Yale NYC ISU Colgate Denver SF UCB LA Houston UCLA

  5. Address for a postal mail to Taiwan Chung-Chih Li Box 5150 Illinois State University Normal, IL 61790 USA 李中志 先生收 永和市 福和路 152號 11樓 之 1 Taipei, 23438 Taiwan

  6. USA Post Office as the Router Regional Post Office Local Post Office Mailman Mailman Air Port Air Port Taiwan Regional Post Office Local Post Office Mailman

  7. SU Internet and Routers Chicago Boston CNY Seattle Yale NYC ISU ISU Denver SF XYZ ITK Lab LA Houston UCLA

  8. TCP/IP Transmission Control Protocol/ Internet Protocol IP Address: (4 bytes) 0 0 0 0 255 255 255 255 256  256  256  256 = 4,294,967,296 128.10.2.1 128.230.208.46 128.230.18.55 149.43.80.141 149.43.3.23

  9. DNS Domain Name System Arthur.cs.purdue.edu apollo.syr.edu rodan.syr.edu ilstu.edu cs.colgate.edu colgate.edu ………….. …………. 128.10.2.1 128.230.208.46 128.230.18.55 138.87.246.1 149.43.3.23 149.43.1.7 ………….. ( some IP may not have a domain name) The table is huge, we don’t want to maintain this table in every computer. • Domain Name Server : • A computer that provides DNS services. • One can let his/her computer uses a specific DNS or let it arbitrarily use an available one.

  10. 128.230 Routers and IP Address Chicago Boston CNY Seattle Yale NYC DNS ……….. cs.colgate.edu = 149.43.3.23 ……….. 149.43.1.7 149.43.3.23 149.43.2.1 …………. Denver 3 SF 2 DNS LA Houston ……….. cs.colgate.edu = 149.43.3.23 ……….. 1 UCLA cs.ucla.edu/~xxx http://cs.colgate.edu/~chungli …………. 131.179.128.25 …………. 131.179.128.25/~xxx http://cs.colgate.edu/~chungli

  11. 128.230 Traveling trough the Internet 5 6 Chicago Boston 4 CNY Seattle Yale NYC 7 DNS ……….. cs.colgate.edu = 149.43.3.23 ……….. 149.43.1.7 149.43.3.23 149.43.2.1 …………. 8 3 Denver SF 131.179.128.25/~xxx http://cs.colgate.edu/~chungli 131.179.128.25/~xxx http://149.43.3.23/~chungli 2 LA Houston 1 UCLA …………. 131.179.128.25 ………….

  12. 128.230 Traveling trough the Internet (2) 5 6 Chicago Boston 4 CNY Seattle Yale 10 9 NYC 7 149.43.1.7 149.43.3.23 149.43.2.1 …………. 8 131.179.128.25/~xxx  (index.html) 11 3 Denver SF 2 12 LA Houston 13 1 UCLA …………. 131.179.128.25 …………. 14

  13. ……………………… dennisliattwcny ……………………… ……………………… …………………………. dli : (dli@twcny.rr.com) seanyboy : (seanyboy@twcny.rr.com) gbush : (gbush@twcny.rr.com) ………………………….. ………………………….. Dynamic IP addresses home.twcny.rr.com 207.211.212.39. CNY twcny.rr.com 24.24.1.140 66.24.2.170 66.24.3.190 66.24.3.180 192.168.0.196 192.168.0.188 192.168.0.190

  14. How do computer talk to each other? At what level?

  15. OSI Model International Organization for Standardization (1984): Open Systems Interconnection reference model. • The model modulizes a sequence of tasks for inter-exchanged information between computers into 7 layers: • Application layer (7) • Presentation layer (6) • Session layer (5) • Transport layer (4) • Network layer (3) • Data Link layer (2) • Physical layer (1) • Each layer should be viewed as a job (task) description but not the actual rules or methods to do the job

  16. OSI Model Analogy Knight Lancelot King Arthur

  17. OSI, Peer-Layer Communication

  18. WWW Original purpose of the World Wide Web was to locate and display information • Created by Tim Berners-Lee in 1990-91 at the European Laboratory for Particle Physics (CERN) in Geneva, Switzerland. • Purpose: to easily access cross-referenced documents, through a method called hypertext linking • Hypertext link (hyperlink): contains a reference to a Web page that can be accessed by a click (URL)

  19. Terminologies • Web page: a document on the Web • Web site: refers to a location on the Internet of Web pages and related files that belong to a company, organization, or individual • Web browser: a program for displaying Web pages • Request: when the user’s browser asks a Web server for a Web page • Web server: a computer that delivers Web pages • Response: what the Web server returns to the Web browser

  20. Terminologies • Uniform Resource Identifier (URI): a generic term for many types of names and addresses on the Web • Uniform Resource Locator (URL): a unique address on the Web • Uniform Resource Name (URN): a name (identity) of a resource on the Web http://www.itk.ilstu.edu/faculty/chungli/ITK368-485/index.html Protocol://…....Domain name…./………….…Directory………….……/…Filename… urn:isbn:0451450523 Urn : Namespace : nameString

  21. Cosmetics Tools or materials to make up faces Face + (???) HTML Document = Hypertext = Text + HTML Tags

  22. Hypertext Markup Language (HTML): a markup language used to create Web pages (HTML pages) • Markup language: a set of characters or symbols that define a document’s logical structure and how to display the document • HTML is based on Standard Generalized Markup Language (SGML) • HTML documents are text documents that contain formatting instructions called tags HTML

  23. HTML:HyperText Markup Language • A tool to make up HyperText • HyperText: text, tables, frames, pictures, images, links, scripts, etc. • A formal language for a Web author to: • Provide information to Search Engines • Instruct web browsers. • How: • Use tags to distinguish the text and instructions.

  24. Structure of HTML document <html> <head> Section • The author may want to provide information about his/her web pages to the web browsers or search engines. </head> <body> Section • Here the web author puts the material for his/her readers. </body> </html>

  25. Tags In general, a tag is an instruction to instruct the web browser how to present the objects ; <h1> This is H1</H1> start tag end tag End tag closes the effect of start tag. Some tags do not have end tags, e.g. <br> : line breaking

  26. Questions: • What will happen if we miss some end tags? • What kind of problem we will face if we want to type “<h1>” in our text. What should we do?

  27. Attribute of Tag Some tags use attributes to specify how to perform their functions. <font color=“green”> Turn me into green </font> Attribute name Attribute value We can specify more than one attribute in a tag. E.g. <font color=“green” size=+2> Turn me bigger and green </font>

  28. <HR> tag Some tags generate objects for the web browser. <hr size=10 color=“green" align="left" width=20%> <hr size=10 color=“red" align=“center" width=50%>

  29. <head> <title> Basic HTML </title> <meta http-equiv="Content-Type" content="text/html; charset=big5"> <meta name="Author" content="Chung-Chih Li"> <meta name="GENERATOR" content="Microsoft FrontPage 3.0"> </head> More on HTML tags, go to the web page of this class

  30. Static HTML file1, file2, file3, file4, file5, file6, file7, file8, file9, file10, file11, file12, file13, file14, …………. ……………….. ……………….. ……………….. ……………….. ……………….. ……………….. I E file6, file9, file100, ……. File server click click click click click need file20 need file34 click click Internet Client Server

  31. Dynamic HTML file1, file2, file3, file4, file5, file6, file7, …………. ……………….. program1, program2, program3, program4, ……………….. data1, data2, date3, 1022 ……………….. program 8 file9, outputs of prog4, program 3, …… program 4 I E Program 7 File server Name: Jane .. Tel: 315 … need file34 Internet Client Server Security!

  32. Form, CGI, Scripts Files (html, ..) CGI programs Java scripts data html, html (java scripts) html,…. CGI prog I E CGI prog. File server form (data) need html Internet Client Server

  33. CGI Common Gateway Interface Interface between Client and Server • Standardize: • I/O format • Common used environmental variables On server side, programs must follow the CGI standards, and hence they are called CGI programs.

  34. CGI Scripts and Programs Scripts Interpreter Results • Perl, Vbasic, Java Scripts.. (they are stored in ASCII files) Exe programs Results • (they are machine codes) Program source compiler Exe programs • C, C++, Java, Fortran ………….

  35. Java Scripts in HTML documents • Literally, a client computer runs nothing but browsers. • Thus, a client computer receives HTML documents only. <html> …… <script type=“text/javascript”> Javascripts </script> …… </html>

  36. Dynamic HTML file1, file2, file3, .. quiz.html ……. Program1…. cgi-bin/generic-grader.pl ……………….. data1, data2, date3, 1022 ……………….. IE <form name=“x” method=“post” action="http://cs.colgate.edu/cgi-bin/generic-grader.pl" ….. </form> 100 out of 100 are correct.. quiz.html result.html generic-grader.pl file server answers.txt Form x ……. ? quiz.html ? answers.txt Internet Client Server ASP.NET does not go beyond the structure but make the job much easier.

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