Web Programming for DB Applications Yuen-Hsien Tseng 2006/04/18.
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Transcript of Web Programming for DB Applications Yuen-Hsien Tseng 2006/04/18.
Web Programmingfor DB Applications
Yuen-Hsien Tseng
2006/04/18
Web Environment• Browser: IE, Firefox, …• Web Server: Apache, IIS, …• DBMS: Access, MS SQL, MySQL, Oracle, …• Web Programming Env.: CGI, ASP, JSP, PH
P
Web Server
DBMS/ DB server
P1
P2
Pn
CGI
ODBC ASP PC
Browser
DB Client
Internet
Server
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
• 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
• $_, @_,
• @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/;
• "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";
