Some standart and simple tasts with MP2 HOWTO

[Vladimir S. Tikhonjuk]

Hi all!

    Our company has a backoffice project written on C++ ( Qt ) for Linux
by my department. But nessesity appear's to make WEB interface, with all
functions which our C++ program does. Now I have to choose among a lot
of languages and technologies of WEB development.

    I have a lot of experience with perl, and we already have an Apache
2 WEB server, so first, I look at  mod_perl. Reading documentation and
making some practice with mod_perl, I didn't find ( or understand ) how
to solve some, for my point of view, standart tasks.

    1. Reading form parameters ( i.e. POST data of request header ).

    I have already read 'perldoc Apache2::RequestRec' about bucket
brigades to get POST data, but I think that it's to difficult for such
simple task, and may be there is another solution ? Here is mine, which
I wrote, before I found "bucket brigades" variant:

======= Part of httpd.conf BEGIN =======

    PerlModule Promtelecom::PostDataParser
    <Location />
      PerlHeaderParserHandler Promtelecom::PostDataParser
    </Location>

======= Part of httpd.conf END =======

======= PostDataParser.pm BEGIN =======

package Promtelecom::PostDataParser;

use strict;
use Apache2::Const -compile => qw( OK );

my %post_data = ();

sub handler {
  my $r = shift;

  if( $r->method eq "POST" ) {
    my $content = "";
    $r->read( $content, $r->headers_in()->get( 'Content-length' ) );

    foreach my $pair ( split( /[&;]/, $content ) ) {
      my ( $key, $value ) = split( '=', $pair, 2 );
      $Promtelecom::PostDataParser::post_data{ $key } = $value;
    }
  }

  return Apache2::Const::OK;
}

1;

======= PostDataParser.pm END =======

    Here I parse POST data into "post_data" hash. So, I can access to
values of this hash from other handlers like this:
$Promtelecom::PostDataParser::post_data{"key"}

    So, the question is: am I right ? This solution works, but I don't
know if its enough right for mod_perl programming style and architecture.

    2. Result of first question  :)  Sessions.

    As I understand, I need session to save ( restore ) user data
between requests. What for ? Now I'll try to explain.

    Here is my another try to work with mod_perl  :)  Simple
Authentication handle, which takes login user and password and try to
make a Database connection. If connection was established - then
Authentication passed,else - not.


======= PostDataParser.pm BEGIN =======
package Promtelecom::Authentication;

use strict;
use Apache2::Const -compile => qw(OK HTTP_UNAUTHORIZED);

$Apache::DBI::DEBUG = 1;

my $user = '';
my $password = '';

sub handler {
  my $r = shift;

  my $status = 0;
  ( $status, $Promtelecom::Authentication::password ) =
$r->get_basic_auth_pw;
  return $status unless $status == Apache2::Const::OK;

  $Promtelecom::Authentication::user = $r->user;

  my $dbh = DBI->connect( 'dbi:Pg:dbname=database;host=database',
$Promtelecom::Authentication::user,
$Promtelecom::Authentication::password, { AutoCommit => 0 } );

  return Apache2::Const::OK if defined $dbh;

  return Apache2::Const::HTTP_UNAUTHORIZED;
}

1;
======= PostDataParser.pm END =======

So, why I need session's or pnote's for passing data between handlers if
I can make vars like $Promtelecom::Authentication::password and
$Promtelecom::Authentication::login and access them from other handlers?

    3. Database persistant connection.

    As I understand, such possibility I can get only using Apache::DBI
module. So, here is my httpd.conf:

======= Part of httpd.conf BEGIN =======

    PerlModule Apache::DBI
    PerlModule Promtelecom::Authentication
    PerlModule Promtelecom::PostDataParser
    <Location />
      PerlAuthenHandler Promtelecom::Authentication
      AuthType Basic
      AuthName "Promtelecom Network"
      Require valid-user
      PerlHeaderParserHandler Promtelecom::PostDataParser
    </Location>

    PerlModule Promtelecom::Debitor
    <Location /debitor>
      SetHandler perl-script
      PerlHandler Promtelecom::Debitor
    </Location>

======= Part of httpd.conf END =======

You have already seen my Promtelecom::Authentication module ( question 2
), so here is a simple code of Promtelecom::Debitor:

======= PostDataParser.pm BEGIN =======

package Promtelecom::Debitor;

use strict;
use Apache2::Const -compile => qw( OK );


sub handler {
  my $r = shift;

  my $dbh = DBI->connect( 'dbi:Pg:dbname=database;host=database',
$Promtelecom::Authentication::user,
$Promtelecom::Authentication::password, { AutoCommit => 0 } );

  return Apache2::Const::OK;
}

1;

======= PostDataParser.pm END =======

So, here is what I'm waiting from mod_perl:

1. Client open browser and enter address http://myserver/debitor
2. Apache ( on myserver ) get the request, and call's PerlAuthenHandler
Promtelecom::Authentication
3. Client get then window with login and password line edits.
4. Client enters login and password.
5. Promtelecom::Authentication gets client's login and password and try
to set database connection using these datas.

In /var/log/apache2/error_log I see something like:

11836 Apache::DBI             new connect to
'dbname=database;host=databaseuserpasswordAutoCommit=0PrintError=1Username=user'

6. If connection established, Apache calls PerlHandler Promtelecom::Debitor
7. Here I think that Apache::DBI will see that
Promtelecom::Authentication already established database connection with
same parameters and  returns me this connection, but I see new string in
err_log here:

11838 Apache::DBI             new connect to
'dbname=database;host=databaseuserpasswordAutoCommit=0PrintError=1Username=user'

Where is a mistake ?

Best regards,
Vladimir S. Tikhonjuk