A Database-Driven Web Application in 18 Lines of Code

From zero to Web-based database application in eight easy steps.

The LAMP combination of Linux, Apache, MySQL and a programming technology (typically Perl, Python or PHP) is a powerful one. Once you've built one Web-based database application, however, you've built them all. From a programmer's perspective, things become boring and repetitive pretty quickly.

I recently worked on my first Web application. I built it on Linux, of course, running through Apache and talking to MySQL. I used Perl as my glue language, with CGI figuring heavily. I created all the code to talk to a MySQL table, adding/editing/updating as need be. And it all worked, which was good. What was bad was, I was faced with repeating this activity (and effort) for each of the remaining tables in my database. In a time-honoured tradition among Perl programmers, I started to look for ways to be constructively lazy. There had to be a better way. After a few false starts and some searching, I found Maypole.

Initially created by Simon Cozens and maintained by Sebastian Riedel, Maypole is a rapid application development framework for Web applications. Maypole's home page promised a fully functioning application in about 20 lines of Perl code. This sounded too good not to try.

Having tried Maypole, I can confirm that Simon and Sebastian are not lying. Only a handful of lines of code is required to build a very functional application. Some setup is required, but—critically—this activity is not programming. Once the setup is complete, any number of applications can be created, each with a handful of lines of code. In the rest of this article, I step you through building an application with Maypole.

Step 1: Install Linux (If Needed)

This step used to require an entire article to describe. Today, a single sentence summarizes. Pick your favourite distribution, and install it.

Having recently taken delivery of a new PC, I grabbed Fedora Core 3 and custom installed everything. If you don't have this luxury, be sure to install the following packages from your chosen distribution: httpd, httpd-devel, mod_perl, mod_perl-devel, mysql (client and server) and Perl.

Step 2: Prepare Your Apache/mod_perl Environment

Increasingly, modern distributions are shipping with release 2 of Apache and version 1.99 of mod_perl, as opposed to the entrenched 1.3.x release of Apache. Thankfully, Maypole can work with either release of Apache and also can be configured to use CGI (if mod_perl is not available). My Fedora installation shipped with release 2.0.52 of Apache and 1.99_16-3 of mod_perl, so that's what I use here. Users on the Maypole mailing list have reported successful installations on the vast majority of Linux platforms, including SuSE, Debian and Red Hat. Maypole also can be installed on Apple's Mac OS X and, with some extra effort, Microsoft's Windows.

As root, I edited Fedora's Apache configuration file at /etc/httpd/conf/httpd.conf and commented out the ServerTokens directive. I then arranged to start Apache automatically at boot time, and fired up the Web server using these commands:

chkconfig httpd on
service httpd start

The lynx text-based browser can be used to check the status of the server with this command:

lynx -head -dump http://localhost/

The results confirm that Apache and mod_perl are up and running, as shown on the third line of this output:

HTTP/1.1 403 Forbidden
Date: Wed, 17 Nov 2004 23:30:01 GMT
Server: Apache/2.0.52 (Fedora)
            mod_perl/1.99_16 Perl/v5.8.5 DAV/2
Accept-Ranges: bytes
Content-Length: 3931
Connection: close
Content-Type: text/html; charset=UTF-8

Happy that all was okay, I re-edited httpd.conf and uncommented the ServerTokens directive, as it is best not to give away too much about the internals of your Web server to potential attackers. While in httpd.conf, I changed the ServerAdmin directive to a more appropriate e-mail address, then set ServerName to the DNS name for my server. I also made a note of the value set for DocumentRoot, which was /var/www/html on my machine.

Step 3: Prepare MySQL

Depending on the distribution you are running, MySQL already may be installed. If MySQL is missing, download it from your distribution's download area, or go to the MySQL Web site. On my Fedora machine, I issued the usual commands to prepare MySQL for use, while logged in as root:

chkconfig mysqld on
service mysqld start

With MySQL running, I then set the MySQL administrator password:

mysqladmin -u root password 'passwordhere'

______________________

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Please help

Justin Rickert's picture

I have tried to get the content of this article to work for three days now. I have finally got all the modules from CPAN installed. However when I try and use the App I get this message in the httpd error log:

failed to resolve handler `ClubDB':

and

Can't locate loadable object for module Apache::Constants

I installed Apache::Constants with
# perl -MCPAN -eshell
# install Apache::Constants

I have followed this article content and dont understant why it don't work.

Fights with Apache

Jason McKenna's picture

I'm running SuSE 9.1 with Apache 2 and had a hard time fighting to get things working. The one thing which took me the longest time to figure out was the Apache::MVC module does a check to see if you're running Apache 1 or 2. If 2 it requires one set of libraries, if 1 then a different set.

They both require Apache::Request, but as far I've been able to determine, this is not available for Apache 2:

if (APACHE2) {
require Apache2;
...
} else { require Apache }
require Apache::Request;

I seem to have fixed the problem by putting the "require Apache::Request" line inside the else block.

I don't know Perl or the Apache modules enough to say if this is a bug in MVC, or if my system is grossly misconfigured. Regardless, Maypole is working for me now, but I'm continuing to research. Any ideas?

Thanks!

Can't compile libapreq2 either

scottebetts's picture

Even though /sbin is in my path already. I'm on FC3 that was upgraded from FC2. I may try a clean new install in order to give this a whirl.

I couldn't get this tutorial

ElaineNormandy's picture

I couldn't get this tutorial to work until I made the following changes:

1. include /sbin in path when compiling libapreq2 module.

2. changed ClubDB.pm to have the following line:

ClubDB->setup( "dbi:mysql:CLUB", "manager", "passwordhere" );

instead of existing ClubDB->setup line.

Hope these tips help someone else save some hours.

Getting it to work

Mitch Kuppinger's picture

In addition to ElaineNormandy's suggestion which was key to getting this to work, I can offer these suggestions:

In ClubDB.pm since at line 9 we are in the ClubDB::Squad package definition, line 9 should be changed from "ClubDB::Player->untaint..." to "ClubDB::Squad->untaint...".

Be VERY carefull with your syntax in ClubDB.pm. For example, using curved braces, '(' and ')', instead of curly braces, '{' abd '}', after 'sub display_columns' causes the display of the associated table to be replaced by a message that the page can't be opened. The log ( logs/error.log) is minimally helpfull with this.

Be sure to restart Apache whenever ClubDB.pm is changed.

Paul Barry's article is thorough but does not walk you thru installing and setting up Apache and mod_perl, if you don't have them. This has to be done right to get the rest to work. Having the source code and all the resultant files from the build process (eg. apxs ) appears to be necessary to install libapreq2. My initial install of fc3 did not have these. It took a bit of poking around to get these required files in place.

All that said, I now have the tools in place to move some very usefull Interbase SQL databases to mysql and serve them up with browser technology to the various offices in our organization. Thanks to Paul Barry, Simon Cozens and Sebastion Riedel.

Getting it to work ... more

barryp's picture

Paul Barry's article is thorough but does not walk you thru installing and setting up Apache and mod_perl, if you don't have them.

I initially had a version of the article that covered installing Apache/mod_perl from source. However, in discussions with LJ's editor, it was decided that the article would be more useful if I targetted a distribution's build of Apache/mod_perl, the thinking being that if a distribution issued a security fix, it could be applied to the system as a result of the distribution's updating system. The idea was that building from source would mean that the user would then be taking on responsibility for updating Apache/mod_perl when security patches were issued. It was felt that people are busy enough, so we stuck with a distribution's Apache/mod_perl package.

My initial install of fc3 did not have these. It took a bit of poking around to get these required files in place.

As the last step of Part 1, I state: "be sure to install the following packages from your chosen distribution: httpd, httpd-devel, mod_perl, mod_perl-devel, mysql (client and server) and Perl.". With these packages installed, APXS and the like are installed for you. I did this on FC3 with no real issues.

Interbase SQL

You may wish to try hooking Maypole up to Interbase and avoid the step of moving your data to MySQL. Maypole is database-independent. Worth checking out.

Thanks to Paul Barry, Simon Cozens and Sebastion Riedel.

Oh my ... all I did was write the article. The "Simons" did all the real work and they deserve all the credit.

Thanks for the comments on the article. Glad you found it useful.

Regards.

Paul.

Paul Barry

getting Maypole (this tutorial) to work

barryp's picture

Unfortunately (or fortunately, depending on how you view things) Maypole and its API is constantly under development. The module is now at release 2.09, whereas my code worked under 2.04 and that was just a few short months ago. The best advice I can give web developers is to subscribe to the Mayole mailing list and to check any list archives. And -- yes -- getting Maypole to work is a challenge but, once it works, I think its worth the heartache.

Paul Barry

Paul Barry

Just the thing I've been pull

Anonymous's picture

Just the thing I've been pulling my hair out over the last 20 mins. Thanks!

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