5555: Web Programming

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5555 Web Programming

• Semester 2, 2008/9

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• Client-side

- program runs in web-browser - no server
control once downloaded - less bandwidth -
insecure

• Server-side

- program runs on web server - uses more
resources - has no control over client
machine - secure
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Client-Side

• Javascript

- Widely-used, particularly for DHTML -
Full-featured language - Cross-platform support

• Java

- Used in the form of applets on web pages -
Slow, but good with graphics - Requires
runtime-environment, but is cross-platform

• VBScript

- Microsoft OS only, hence limited applicability
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Server-Side 1 - CGI

• Perl (.pl, .cgi)

- Most widely-used server scripting language on
the internet - Large number of add-on libraries -
Works on Windows and Unix - OpenSource

• PHP (.php, .php3, .php4)

• - rapidly-growing
• - HTML-embedded
• - Works on Windows and Unix
• OpenSource
• Object-oriented many useful classes available
  free on web

• ASP (.asp)

• - MS-specific (i.e. Windows only, AND Windows
  web-servers only
• HTML-embedded
• Can run uner Unix with Chillisoft (expensive)

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Server-Side 2

• Python (.py)

• Cult following. Similar to Perl in use
  smaller user base.
• Can run under Windows or Unix

• Coldfusion (.cfm)

• Application server
• Good for non-programmers
• Can link easily to various database back-ends

• Java (.jsp, .jhtml)

• growing userbase
• requires add-on libraries for server

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Server/Client

• AJAX

• uses XML
• Asynchronous Javascript And XML

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Client/Server Interaction
CLIENT
SERVER
http//143.52.5.51/index.html
Client issues a request for a page
Server returns requested page
Client clicks a link to another page
Server returns requested page
etc
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TEMPERATURE EXAMPLE The HTML code
ltbodygt lth1gtltfont color"Green" face"Verdana"
Size"4"gtltbgtTemperature Converterlt/bgtlt/fontgtlthr
size"1"gtlt/h1gt Insert a number in either input
field, and the number will be converted into
either Celsius or Fahrenheit. ltpgtlt/pgt ltform
name"myform"gt ltinput name"celsius"
onkeyup"convert('C')"gt degrees Celsius ltpgtis
equal tolt/pgt ltinput name"fahrenheit"
onkeyup"convert('F')"gt degrees Fahrenheit
lt/formgt Note that the ltbgtMath.roundlt/bgt method
is used, so that the result will be returned as a
whole number. lt/bodygt lt/htmlgt
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TEMPERATURE EXAMPLE The Javascript
ltscript type"text/javascript"gt function
convert(degree) if (degree"C")
Fdocument.myform.celsius.value 9 / 5
32 document.myform.fahrenheit.valueMath.round(F)
else C(document.myform.fahrenheit.valu
e -32) 5 / 9 document.myform.celsius.valueMath
.round(C) lt/scriptgt