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Understanding the World Wide Web: History, Protocols, and Client-Server Architecture

This document explores the evolution of the World Wide Web, tracing its origins from ARPAnet in 1983 to the establishment of WWW protocols in 1991. It details the significance of TCP/IP communication and highlights key protocols like HTTP and HTML. The architecture of client-server interactions is explained, showcasing how browsers and web servers communicate using various formats. Additionally, it discusses limitations of static maps, introduces interactive mapping solutions, and delves into CGI applications and databases, providing a comprehensive overview of web functionality.

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Understanding the World Wide Web: History, Protocols, and Client-Server Architecture

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  1. How the World Wide Web works Barend Köbben International Institute for Geo-information Science and Earth Observation (ITC)

  2. History of the Web • (1983) ARPAnet, USEnet en EUnet adopt TCP/IP communication: birth of the Internet • many protocols run “on top of” TCP/IP (telnet, ftp, smpt) • because of IP-adressing all networks can can be seen as one big network • (1991) definition of the WWW-protocols: • HTTP: HyperText Transfer Protocol • HTML: HyperText Markup Language (1969) start of ARPAnet

  3. DNS aliasing SURFNET admin nl-domain: xx.xx.nl ITC router admin ITC-domain: xx.itc.nl NVK server 192.92.92.70 IP-adressing & DNS (domain name servers) INTERNET www.kartografie.nl =kartoweb.itc.nl

  4. Can I have that file? Here it is... HTTP communication • Client-server architecture Client Server Webserver (IIS, Netscape, HTTPd) Browser (Explorer, Netscape, Opera)

  5. HTML code • <P>Hello<B>World</B><HR>How are<I>you</I>?<P><A HREF= ”otherfile.html”>Click here</a> to go. • Looks like: • Hello World • How are you? • Click here to go.

  6. PUT file.gif PUT file.html GET file.gif GET file.html file.gif <img src = “file.gif”><br><i>STATIC </i> MAP Standard configuration http:// www.itc.nl /file.html STATIC MAP

  7. Constraints • Standard configuration offers: • HTTP communication-protocol • HTML–, GIF– en JPEG–formats • Static maps only • No interactivity (except “clickable maps”) • Overcoming the constraints: • Only possible by adding data-formats and protocols • Possible loss of platform independency

  8. file.pdf <img src = “file.pdf”><br><i>interactive </i> map Plugins (client-side) PDF-READER interactive map

  9. Java Virtual Machine map.class Java-applet code map applet <applet src = “map.class”> <br> map applet Java applets (client-side)

  10. Java Virtual Machine JavaScript (client-side) <script > <!-- Document.write(“map”); } //--> </script> map

  11. CGI-APPLI-CATION itc CGI–applications (server-side) www.kartografie.nl /CGI?makemap&title=“itc”

  12. <img src = <% foundrecords.image %><br>database stuff database stuff Active Server Pages (server-side)handles JavaScript or VBscript Microsoft IIS HTML in memory <img src = map.gif><br>database stuff server-plugin(asp.dll) a

  13. Java Virtual Machine map.class Java-applet code map applet <%applet src = “map.class”%> <br> map applet Java servlets (server-side)

  14. server-plugin(esrimap.dll) Java Virtual Machine arcview map mapcafe.class Java-applet code ArcView-IMS: a mixed solution

  15. administrator(blenke@itc.nl) IIS serveritcnt07.itc.nl special dir “www” on personal drive M: windowsnetwork http Anonymous access (Web) Web-browsers authors Internal server (itcnt07 student sites) • Only available within ITC (within “firewall”)

  16. administrator(kartoweb@itc.nl) Kartoweb server ftp http username/password privileges Anonymous access (Web) Web-browsers authors External Web server (eg. Kartoweb)

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