NAME

    CGI::Application::Plugin::Session - Add CGI::Session support to
    CGI::Application

SYNOPSIS

     use CGI::Application::Plugin::Session;
    
     my $language = $self->session->param('language');

DESCRIPTION

    CGI::Application::Plugin::Session seamlessly adds session support to
    your CGI::Application modules by providing a CGI::Session object that
    is accessible from anywhere in the application.

    Lazy loading is used to prevent expensive file system or database calls
    from being made if the session is not needed during this request. In
    other words, the Session object is not created until it is actually
    needed. Also, the Session object will act as a singleton by always
    returning the same Session object for the duration of the request.

    This module aims to be as simple and non obtrusive as possible. By not
    requiring any changes to the inheritance tree of your modules, it can
    be easily added to existing applications. Think of it as a plugin
    module that adds a couple of new methods directly into the
    CGI::Application namespace simply by loading the module.

METHODS

 session

    This method will return the current CGI::Session object. The
    CGI::Session object is created on the first call to this method, and
    any subsequent calls will return the same object. This effectively
    creates a singleton session object for the duration of the request.
    CGI::Session will look for a cookie or param containing the session ID,
    and create a new session if none is found. If session_config has not
    been called before the first call to session, then it will choose some
    sane defaults to create the session object.

      # retrieve the session object
      my $session = $self->session;
    
      - or -
    
      # use the session object directly
      my $language = $self->session->param('language');

 session_config

    This method can be used to customize the functionality of the
    CGI::Application::Plugin::Session module. Calling this method does not
    mean that a new session object will be immediately created. The session
    object will not be created until the first call to $self->session. This
    'lazy loading' can prevent expensive file system or database calls from
    being made if the session is not needed during this request.

    The recommended place to call session_config is in the cgiapp_init
    stage of CGI::Application. If this method is called after the session
    object has already been accessed, then it will die with an error
    message.

    If this method is not called at all then a reasonable set of defaults
    will be used (the exact default values are defined below).

    The following parameters are accepted:

    CGI_SESSION_OPTIONS

      This allows you to customize how the CGI::Session object is created
      by providing a list of options that will be passed to the
      CGI::Session constructor. Please see the documentation for
      CGI::Session for the exact syntax of the parameters.

    DEFAULT_EXPIRY

      CGI::Session Allows you to set an expiry time for the session. You
      can set the DEFAULT_EXPIRY option to have a default expiry time set
      for all newly created sessions. It takes the same format as the
      $session->expiry method of CGI::Session takes. Note that it is only
      set for new session, not when a session is reloaded from the store.

    COOKIE_PARAMS

      This allows you to customize the options that are used when creating
      the session cookie. For example you could provide an expiry time for
      the cookie by passing -expiry => '+24h'. The -name and -value
      parameters for the cookie will be added automatically unless you
      specifically override them by providing -name and/or -value
      parameters. See the CGI::Cookie docs for the exact syntax of the
      parameters.

      NOTE: You can do the following to get both the cookie name and the
      internal name of the CGI::Session object to be changed:

        $self->session_config(
          CGI_SESSION_OPTIONS => [
            $driver,
            $self->query,
            \%driver_options,
            { name => 'new_cookie_name' } # change cookie and session name
          ]
        );

      Also, if '-name' parameter and 'name' of session don't match a
      warning will be emitted.

    SEND_COOKIE

      If set to a true value, the module will automatically add a cookie
      header to the outgoing headers if a new session is created (Since the
      session module is lazy loaded, this will only happen if you make a
      call to $self->session at some point to create the session object).
      This option defaults to true. If it is set to false, then no session
      cookies will be sent, which may be useful if you prefer URL based
      sessions (it is up to you to pass the session ID in this case).

    The following example shows what options are set by default (ie this is
    what you would get if you do not call session_config).

     $self->session_config(
              CGI_SESSION_OPTIONS => [ "driver:File", $self->query, {Directory=>'/tmp'} ],
              COOKIE_PARAMS       => {
                                       -path  => '/',
                                     },
              SEND_COOKIE         => 1,
     );

    Here is a more customized example that uses the PostgreSQL driver and
    sets an expiry and domain on the cookie.

     $self->session_config(
              CGI_SESSION_OPTIONS => [ "driver:PostgreSQL;serializer:Storable", $self->query, {Handle=>$dbh} ],
              COOKIE_PARAMS       => {
                                       -domain  => 'mydomain.com',
                                       -expires => '+24h',
                                       -path    => '/',
                                       -secure  => 1,
                                     },
     );

 session_cookie

    This method will add a cookie to the outgoing headers containing the
    session ID that was assigned by the CGI::Session module.

    This method is called automatically the first time $self->session is
    accessed if SEND_COOKIE was set true, which is the default, so it will
    most likely never need to be called manually.

    NOTE that if you do choose to call it manually that a session object
    will automatically be created if it doesn't already exist. This removes
    the lazy loading benefits of the plugin where a session is only
    created/loaded when it is required.

    It could be useful if you want to force the cookie header to be sent
    out even if the session is not used on this request, or if you want to
    manage the headers yourself by turning SEND_COOKIE to false.

      # Force the cookie header to be sent including some
      # custom cookie parameters
      $self->session_cookie(-secure => 1, -expires => '+1w');

 session_loaded

    This method will let you know if the session object has been loaded
    yet. In other words, it lets you know if $self->session has been
    called.

      sub cgiapp_postrun {
        my $self = shift;
        $self->session->flush if $self->session_loaded;;
      }

 session_recreate

    This method will delete the existing session, and create a brand new
    one for you with a new session ID. It copies over all existing
    parameters into the new session.

    This can be useful to protect against some login attacks when storing
    authentication tokens in the session. Very briefly, an attacker loads a
    page on your site and creates a session, then tries to trick a victim
    into loading this page with the same session ID (possibly by embedding
    it in a URL). Then if the victim follows the link and subsequently logs
    into their account, the attacker will have a valid session ID where the
    session is now logged in, and hence the attacker has access to the
    victims account.

      sub mylogin {
        my $self = shift;
        if ($newly_authenticated) {
            $self->session_recreate;
        }
      }

 session_delete

    This method will perform a more comprehensive clean-up of the session,
    calling both the CGI::Session delete() method, but also deleting the
    cookie from the client, if you are using cookies.

      sub logout {
        my $self = shift;
        $self->session_delete;
        # what now?  redirect user back to the homepage?
      }

EXAMPLE

    In a CGI::Application module:

      # configure the session once during the init stage
      sub cgiapp_init {
        my $self = shift;
    
        # Configure the session
        $self->session_config(
           CGI_SESSION_OPTIONS => [ "driver:PostgreSQL;serializer:Storable", $self->query, {Handle=>$self->dbh} ],
           DEFAULT_EXPIRY      => '+1w',
           COOKIE_PARAMS       => {
                                    -expires => '+24h',
                                    -path    => '/',
                                  },
           SEND_COOKIE         => 1,
        );
    
      }
    
      sub cgiapp_prerun {
        my $self = shift;
    
        # Redirect to login, if necessary
        unless ( $self->session->param('~logged-in') ) {
          $self->prerun_mode('login');
        }
      }
    
      sub my_runmode {
        my $self = shift;
    
        # Load the template
        my $template = $self->load_tmpl('my_runmode.tmpl');
    
        # Add all the session parameters to the template
        $template->param($self->session->param_hashref());
    
        # return the template output
        return $template->output;
      }

TODO

      * I am considering adding support for other session modules in the
      future, like Apache::Session and possibly others if there is a
      demand.

      * Possibly add some tests to make sure cookies are accepted by the
      client.

      * Allow a callback to be executed right after a session has been
      created

SEE ALSO

    CGI::Application, CGI::Session, perl(1)

AUTHOR

    Cees Hek <ceeshek@gmail.com>

LICENSE

    Copyright (C) 2004, 2005 Cees Hek <ceeshek@gmail.com>

    This library is free software. You can modify and or distribute it
    under the same terms as Perl itself.

