NAME
    POE::Component::Server::POP3 - A POE framework for authoring POP3
    servers

SYNOPSIS
      # A simple POP3 Server 
      use strict;
      use POE;
      use POE::Component::Server::POP3

DESCRIPTION
    POE::Component::Server::POP3 is a POE component that provides a
    framework for authoring POP3 <http://www.faqs.org/rfcs/rfc1939.html>
    servers with POE.

    It creates a listening TCP socket ( by default on port 110 ) and accepts
    connections from multiple clients. Each connecting client is assigned a
    unique ID. Input from clients generates events that other POE components
    and sessions may register to receive. The POP3 poco also handles sending
    output to applicable clients.

    One may either interface with the component via the POE API or via
    POE::Component::Pluggable plugins.

CONSTRUCTOR
    spawn
        Takes a number of optional arguments:

          'alias', set an alias on the component;
          'address', bind the listening socket to a particular address;
          'port', listen on a particular port, default is 110;
          'options', a hashref of POE::Session options;
          'hostname', the name that the server will identify as;
          'version', change the version string reported in initial client connections;
          'handle_connects', set this to a false value to stop the component sending
                initial connection responses to connecting clients;

        Returns a POE::Component::Server::POP3 object.

METHODS
    session_id
        Returns the POE::Session ID of the component.

    shutdown
        Terminates the component. Shuts down the listener and disconnects
        connected clients.

    send_event
        Sends an event through the component's event handling system.

    send_to_client
        Send some output to a connected client. First parameter must be a
        valid client id. Second parameter is a string of text to send.

    getsockname
        Access to the POE::Wheel::SocketFactory method of the underlying
        listening socket.

INPUT EVENTS
    These are events that the component will accept:

    register
        Takes N arguments: a list of event names that your session wants to
        listen for, minus the 'pop3d_' prefix, ( this is similar to
        POE::Component::IRC ).

        Registering for 'all' will cause it to send all POP3D-related events
        to you; this is the easiest way to handle it.

    unregister
        Takes N arguments: a list of event names which you don't want to
        receive. If you've previously done a 'register' for a particular
        event which you no longer care about, this event will tell the POP3D
        to stop sending them to you. (If you haven't, it just ignores you.
        No big deal).

    shutdown
        Terminates the component. Shuts down the listener and disconnects
        connected clients.

    send_event
        Sends an event through the component's event handling system.

    send_to_client
        Send some output to a connected client. First parameter must be a
        valid client ID. Second parameter is a string of text to send.

OUTPUT EVENTS
    The component sends the following events to registered sessions:

    pop3d_registered
        This event is sent to a registering session. ARG0 is the
        POE::Component::Server::POP3 object.

    pop3d_listener_failed
        Generated if the component cannot either start a listener or there
        is a problem accepting client connections. ARG0 contains the name of
        the operation that failed. ARG1 and ARG2 hold numeric and string
        values for $!, respectively.

    pop3d_connection
        Generated whenever a client connects to the component. ARG0 is the
        client ID, ARG1 is the client's IP address, ARG2 is the client's TCP
        port. ARG3 is our IP address and ARG4 is our socket port.

        If 'handle_connects' is true ( which is the default ), the component
        will automatically send an initial connection response to the
        client.

    pop3d_disconnected
        Generated whenever a client disconnects. ARG0 is the client ID.

    pop3d_cmd_*
        Generated for each POP3 command that a connected client sends to us.
        ARG0 is the client ID. ARG1 .. ARGn are any parameters that are sent
        with the command. Check the RFC
        <http://www.faqs.org/rfcs/rfc1939.html> for details.

PLUGINS
    POE::Component::Server::POP3 utilises POE::Component::Pluggable to
    enable a POE::Component::IRC type plugin system.

  PLUGIN HANDLER TYPES
    There are two types of handlers that can registered for by plugins,
    these are

    POP3D
        These are the 'pop3d_' prefixed events that are generated. In a
        handler arguments are passed as scalar refs so that you may mangle
        the values if required.

    POP3C
        These are generated whenever a response is sent to a client. Again,
        any arguments passed are scalar refs for manglement. There is really
        on one type of this handler generated 'POP3C_response'

  PLUGIN EXIT CODES
    Plugin handlers should return a particular value depending on what
    action they wish to happen to the event. These values are available as
    constants which you can use with the following line:

      use POE::Component::Server::POP3::Constants qw(:ALL);

    The return values have the following significance:

    POP3D_EAT_NONE
        This means the event will continue to be processed by remaining
        plugins and finally, sent to interested sessions that registered for
        it.

    POP3D_EAT_CLIENT
        This means the event will continue to be processed by remaining
        plugins but it will not be sent to any sessions that registered for
        it. This means nothing will be sent out on the wire if it was an
        POP3C event, beware!

    POP3D_EAT_PLUGIN
        This means the event will not be processed by remaining plugins, it
        will go straight to interested sessions.

    POP3D_EAT_ALL
        This means the event will be completely discarded, no plugin or
        session will see it. This means nothing will be sent out on the wire
        if it was an POP3C event, beware!

  PLUGIN METHODS
    The following methods are available:

    pipeline
        Returns the POE::Component::Pluggable::Pipeline object.

    plugin_add
        Accepts two arguments:

          The alias for the plugin
          The actual plugin object

        The alias is there for the user to refer to it, as it is possible to
        have multiple plugins of the same kind active in one
        POE::Component::Server::POP3 object.

        This method goes through the pipeline's push() method.

         This method will call $plugin->plugin_register( $pop3d )

        Returns the number of plugins now in the pipeline if plugin was
        initialized, undef if not.

    plugin_del
        Accepts one argument:

          The alias for the plugin or the plugin object itself

        This method goes through the pipeline's remove() method.

        This method will call $plugin->plugin_unregister( $pop3d )

        Returns the plugin object if the plugin was removed, undef if not.

    plugin_get
        Accepts one argument:

          The alias for the plugin

        This method goes through the pipeline's get() method.

        Returns the plugin object if it was found, undef if not.

    plugin_list
        Has no arguments.

        Returns a hashref of plugin objects, keyed on alias, or an empty
        list if there are no plugins loaded.

    plugin_order
        Has no arguments.

        Returns an arrayref of plugin objects, in the order which they are
        encountered in the pipeline.

    plugin_register
        Accepts the following arguments:

          The plugin object
          The type of the hook, POP3D or POP3C
          The event name(s) to watch

        The event names can be as many as possible, or an arrayref. They
        correspond to the prefixed events and naturally, arbitrary events
        too.

        You do not need to supply events with the prefix in front of them,
        just the names.

        It is possible to register for all events by specifying 'all' as an
        event.

        Returns 1 if everything checked out fine, undef if something's
        seriously wrong

    plugin_unregister
        Accepts the following arguments:

          The plugin object
          The type of the hook, pop3D or POP3C
          The event name(s) to unwatch

        The event names can be as many as possible, or an arrayref. They
        correspond to the prefixed events and naturally, arbitrary events
        too.

        You do not need to supply events with the prefix in front of them,
        just the names.

        It is possible to register for all events by specifying 'all' as an
        event.

        Returns 1 if all the event name(s) was unregistered, undef if some
        was not found.

  PLUGIN TEMPLATE
    The basic anatomy of a plugin is:

            package Plugin;

            # Import the constants, of course you could provide your own 
            # constants as long as they map correctly.
            use POE::Component::Server::POP3::Constants qw( :ALL );

            # Our constructor
            sub new {
                    ...
            }

            # Required entry point for plugins
            sub plugin_register {
                    my( $self, $pop3d ) = @_;

                    # Register events we are interested in
                    $pop3d->plugin_register( $self, 'POP3D', qw(all) );

                    # Return success
                    return 1;
            }

            # Required exit point for pluggable
            sub plugin_unregister {
                    my( $self, $pop3d ) = @_;

                    # Pluggable will automatically unregister events for the plugin

                    # Do some cleanup...

                    # Return success
                    return 1;
            }

            sub _default {
                    my( $self, $pop3d, $event ) = splice @_, 0, 3;

                    print "Default called for $event\n";

                    # Return an exit code
                    return POP3D_EAT_NONE;
            }

AUTHOR
    Chris "BinGOs" Williams <chris@bingosnet.co.uk>

SEE ALSO
    POE::Component::Pluggable

    RFC 1939 <http://www.faqs.org/rfcs/rfc1939.html>