WebProgramming
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Transcript WebProgramming
Web Programming
for DB Applications
Yuen-Hsien Tseng
2006/04/18
Web Environment
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Browser: IE, Firefox, …
Web Server: Apache, IIS, …
DBMS: Access, MS SQL, MySQL, Oracle, …
Web Programming Env.: CGI, ASP, JSP,
PHP
Server
P1
P2
CGI
ODBC
Pn
Web Server
ASP
DBMS/ DB server
Browser
Internet
PC
DB Client
Web Server Administration
• Virtual Path:
– Root dir: Where is http://localhost/ in file system
• Default index page: index.htm[l], welcome.htm, …
– User dir: How http://localhost/~sam/ maps to
d:/sam/public_html
– How http://localhost/demo/ maps to d:/demo
• Executable and non-executable files
– Configurations and File permissions
– http://www.cgi101.com/book/connect/winxp.html
• Port number
Apache Configuration
• An example configuration to run a program:
Alias /~tseng/ "D:/Sam/public_html/"
<Directory "D:/Sam/public_html">
Options Indexes MultiViews ExecCGI
AllowOverride AuthConfig
Order allow,deny
Allow from all
</Directory>
CGI (Common Gateway Interface)
• Messages sent to Web server
– print “Content type: text/html\n\n<html>…”;
• Message received from Web server
– URL-encoding/decoding
– method = Get or Post
• http://localhost/test.pl?name=sam&age=40
<form action=“test.pl” method=Post>
Name: <input type=text name=“name” value=“sam”>
Age: <input type=text name=“age” value=“40”>
<input type=submit value=“Hit me!”>
</form>
Introduction to Perl
• Invented by Larry Wall in late 1980’s
• Combined the merits of many languages
– C/C++, Unix Shell, …
– String Processing, Regular Expression, …
• Suitable for
– File management
– String manipulation
– Process control
• Lot of resources in source codes
– http://www.cpan.org/
Perl Basics
• Data Types
– Scalar (numeric, strings), array, hash, reference
• Flow control
– If elsif else, for, foreach, while, next, last
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Special variables
Subroutines
Regular Expressions
Reference and Object-oriented programming
Data types
• Scalar
– $a=1; $b=1.2; $a = $a . $b . “=sam”;
• Array
– @C=(1, “e”, 3.4); $c=$C[1]; @a = @C[0..1];
– $a = pop @C; $b= unshift @C; shift @C, ‘c’; push @a, ‘e’;
• Hash
– %H=(‘sam’, 4, ‘joe’, 2); %G=(‘sam’=>4, ‘joe’=>2);
– %T=reverse %H;
• Reference
– $b=\@C; $a=$b->[0];
– $a=\%H; $b=($a->{‘sam’} == 4)?’Yes’:”no”;
• http://www.cgi101.com/book/ch2/text.html
Flow control
foreach (@A) {
next if /^\d/; # next unless not /^\d/;
last if /^\s*$/;
print ;
}
for($i=0; $i<$n; $i+=2) { print $A[$i]; }
While (<condition>) { … }
Special Variables
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$_, @_,
@ARGV
Sort { $b eq $a } keys %H;
Sort { $H{$b} <=> $H{$a} } keys %H;
Subroutines
($r, $i) = &add($r1, $i1, $r2, $i2, “no”, “use”);
sub add {
my($r1, $i1, $r2, $i2, @r) = @_;
return ($r1+$r2, $i2+$i2);
}
Regular Expressions
• print "It matches\n" if "Hello World" =~ /World/;
– $greeting = "World";
– print "It matches\n" if "Hello World" =~ /$greeting/;
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"Hello World" =~ /world/; # doesn't match, case sensitive
"Hello World" =~ /o W/; # matches, ' ' is an ordinary char
"Hello World" =~ /World /; # doesn't match, no ' ' at end
Metacharacters : {}[]()^$.|*+?\
– "2+2=4" =~ /2+2/; # doesn't match, + is a metacharacter
– "2+2=4" =~ /2\+2/; # matches, \+ is treated like an ordinary +
– /[yY][eE][sS]/; # match 'yes' in a case-insensitive way
• # 'yes', 'Yes', 'YES', etc.
– /yes/i;
# also match 'yes' in a case-insensitive way
– /item[0-9]/; # matches 'item0' or ... or 'item9'
– /[0-9a-fA-F]/; # matches a hexadecimal digit
• $time =~ /(\d\d):(\d\d):(\d\d)/; # match hh:mm:ss format
– $hours = $1;
$minutes = $2;
$seconds = $3;
More tutorials
• Reference
– See c:/Perl/html/lib/Pod/perlreftut.html
• Object-oriented programming
– See c:/Perl/html/lib/Pod/perltoot.html
CGI Module
and Environment Variables
• See
– http://www.cgi101.com/book/ch3/text.html
– c:/Perl/html/lib/CGI.html
• Use CGI; print param(‘name’);
• print "Caller = $ENV{HTTP_REFERER}\n";