NAME

POE::Component::Client::TCP - a simplified TCP client

SYNOPSIS

  use POE qw(Component::Client::TCP);

  # Basic usage.

  POE::Component::Client::TCP->new
    ( RemoteAddress => "127.0.0.1",
      RemotePort    => "chargen",
      ServerInput   => sub {
        my $input = $_[ARG0];
        print "from server: $input\n";
      }
    );

  # Complete usage.

  POE::Component::Client::TCP->new
    ( RemoteAddress => "127.0.0.1",
      RemotePort    => "chargen",

      Connected     => \&handle_connect,
      ConnectError  => \&handle_connect_error,
      Disconnected  => \&handle_disconnect,

      ServerInput   => \&handle_server_input,
      ServerError   => \&handle_server_error,
      ServerFlushed => \&handle_server_flush,

      Filter        => "POE::Filter::Something",

      InlineStates  => { ... },
      PackageStates => [ ... ],
      ObjectStates  => [ ... ],
    );

  # Sample callbacks.

  sub handle_connect {
    my ($socket, $peer_address, $peer_port) = @_[ARG0, ARG1, ARG2];
  }

  sub handle_connect_error {
    my ($syscall_name, $error_number, $error_string) = @_[ARG0, ARG1, ARG2];
  }

  sub handle_disconnect {
    # no special parameters
  }

  sub handle_server_input {
    my $input_record = $_[ARG0];
  }

  sub handle_server_error {
    my ($syscall_name, $error_number, $error_string) = @_[ARG0, ARG1, ARG2];
  }

  sub handle_server_flush {
    # no special parameters
  }

  # Reserved HEAP variables:

  $heap->{server}   = ReadWrite wheel representing the server
  $heap->{shutdown} = shutdown flag (check to see if shutting down)
  $heap->{connected} = connected flag (check to see if session is connected)

  # Accepted public events.

  $kernel->yield( "shutdown" )   # shut down a connection
  $kernel->yield( "reconnect" )  # reconnect to a server

DESCRIPTION

The TCP client component hides the steps needed to create a client using Wheel::SocketFactory and Wheel::ReadWrite. The steps aren't many, but they're still tiresome after a while.

POE::Component::Client::TCP supplies common defaults for most callbacks and handlers. The authors hope that clients can be created with as little work as possible.

Constructor Parameters

Alias

Alias is an optional component alias. It's used to post events to the TCP client component from other sessions. The most common use of Alias is to allow a client component to receive "shutdown" and "reconnect" events from a user interface session.

ConnectError

ConnectError is an optional callback to handle SocketFactory errors. These errors happen when a socket can't be created or connected to a remote host.

ConnectError must contain a subroutine reference. The subroutine will be called as a SocketFactory error handler. In addition to the usual POE event parameters, ARG0 will contain the name of the syscall that failed. ARG1 will contain the numeric version of $! after the failure, and ARG2 will contain $!'s string version.

Depending on the nature of the error and the type of client, it may be useful to post a reconnect event from ConnectError's callback.

  sub handle_connect_error {
    $_[KERNEL]->delay( reconnect => 60 );
  }

The component will shut down after ConnectError if a reconnect isn't requested.

Connected

Connected is an optional callback to notify a program that SocketFactory succeeded. This is an advisory callback, and it should not create a ReadWrite wheel itself. The component will handle setting up ReadWrite.

ARG0 contains a socket handle. It's not necessary to save this under most circumstances. ARG1 and ARG2 contain the peer address and port as returned from getpeername().

Disconnected

Disconnected is an optional callback to notify a program that an established server connection has shut down. It has no special parameters.

For persistent connections, such as MUD bots or long-running services, a useful thing to do from a Disconnected handler is reconnect. For example, this reconnects after waiting a minute:

  sub handle_disconnect {
    $_[KERNEL]->delay( reconnect => 60 );
  }

The component will shut down after disconnecting if a reconnect isn't requested.

Filter

Filter specifies the type of filter that will parse input from a server. It may either be a scalar or a list reference. If it is a scalar, it will contain a POE::Filter class name. If it is a list reference, the first item in the list will be a POE::Filter class name, and the remaining items will be constructor parameters for the filter.

Filter is optional. The component will supply a "POE::Filter::Line" instance none is specified.

InlineStates

InlineStates holds a hashref of inline coderefs to handle events. The hashref is keyed on event name. For more information, see POE::Session's create() method.

ObjectStates

ObjectStates holds a list reference of objects and the events they handle. For more information, see POE::Session's create() method.

PackageStates

PackageStates holds a list reference of Perl package names and the events they handle. For more information, see POE::Session's create() method.

RemoteAddress

RemoteAddress contains the address to connect to. It is required and may be a host name ("poe.perl.org") a dotted quad ("127.0.0.1") or a packed socket address.

RemotePort

RemotePort contains the port to connect to. It is required and may be a service name ("echo") or number (7).

ServerError

ServerError is an optional callback to notify a program that an established server connection has encountered some kind of error. Like with ConnectError, it accepts the traditional error parameters:

ARG0 contains the name of the syscall that failed. ARG1 contains the numeric failure code from $!. ARG2 contains the string version of $!.

The component will shut down after a server error if a reconnect isn't requested.

ServerFlushed

ServerFlushed is an optional callback to notify a program that ReadWrite's output buffers have completely flushed. It has no special parameters.

The component will shut down after a server flush if $heap->{shutdown} is set.

ServerInput

ServerInput is a required callback. It is called for each input record received from a server. ARG0 contains the input record, the format of which is determined by POE::Component::Client::TCP's Filter parameter.

The ServerInput function will stop being called when $heap->{shutdown} is true.

Public Events

reconnect

Instruct the TCP client component to reconnect to the server. If it's already connected, it will disconnect harshly, discarding any pending input or output data.

shutdown

When a Client::TCP component receives a shutdown event, it initiates a graceful shutdown. Any subsequent server input will be ignored, and any pending output data will be flushed. Once the connection is dealt with, the component will self-destruct.

SEE ALSO

POE::Component::Server::TCP, POE::Wheel::SocketFactory, POE::Wheel::ReadWrite, POE::Filter

CAVEATS

This may not be suitable for complex client tasks.

This looks nothing like what Ann envisioned.

AUTHORS & COPYRIGHTS

POE::Component::Client::TCP is Copyright 2001 by Rocco Caputo. All rights are reserved. POE::Component::Client::TCP is free software, and it may be redistributed and/or modified under the same terms as Perl itself.

POE::Component::Client::TCP is based on code, used with permission, from Ann Barcomb <kudra@domaintje.com>.

POE::Component::Client::TCP is based on code, used with permission, from Jos Boumans <kane@cpan.org>.