POE::Wheel::ListenAccept - accept connections from regular listening sockets
See "SYNOPSIS" in POE::Wheel::SocketFactory for a simpler version of this program.
#!perl
use warnings;
use strict;
use IO::Socket;
use POE qw(Wheel::ListenAccept Wheel::ReadWrite);
POE::Session->create(
inline_states => {
_start => sub {
# Start the server.
$_[HEAP]{server} = POE::Wheel::ListenAccept->new(
Handle => IO::Socket::INET->new(
LocalPort => 12345,
Listen => 5,
),
AcceptEvent => "on_client_accept",
ErrorEvent => "on_server_error",
);
},
on_client_accept => sub {
# Begin interacting with the client.
my $client_socket = $_[ARG0];
my $io_wheel = POE::Wheel::ReadWrite->new(
Handle => $client_socket,
InputEvent => "on_client_input",
ErrorEvent => "on_client_error",
);
$_[HEAP]{client}{ $io_wheel->ID() } = $io_wheel;
},
on_server_error => sub {
# Shut down server.
my ($operation, $errnum, $errstr) = @_[ARG0, ARG1, ARG2];
warn "Server $operation error $errnum: $errstr\n";
delete $_[HEAP]{server};
},
on_client_input => sub {
# Handle client input.
my ($input, $wheel_id) = @_[ARG0, ARG1];
$input =~ tr[a-zA-Z][n-za-mN-ZA-M]; # ASCII rot13
$_[HEAP]{client}{$wheel_id}->put($input);
},
on_client_error => sub {
# Handle client error, including disconnect.
my $wheel_id = $_[ARG3];
delete $_[HEAP]{client}{$wheel_id};
},
}
);
POE::Kernel->run();
exit;POE::Wheel::ListenAccept implements non-blocking accept() calls for plain old listening server sockets. The application provides the socket, using some normal means such as socket(), IO::Socket::INET, or IO::Socket::UNIX. POE::Wheel::ListenAccept monitors the listening socket and emits events whenever a new client has been accepted.
Please see POE::Wheel::SocketFactory if you need non-blocking connect() or a more featureful listen/accept solution.
POE::Wheel::ListenAccept only accepts client connections. It does not read or write data, so it neither needs nor includes a put() method. POE::Wheel::ReadWrite generally handles the accepted client socket.
new() creates a new POE::Wheel::ListenAccept object for a given listening socket. The object will generate events relating to the socket for as long as it exists.
new() accepts two required named parameters:
The Handle constructor parameter must contain a listening socket handle. POE::Wheel::FollowTail will monitor this socket and accept() new connections as they arrive.
AcceptEvent is a required event name that POE::Wheel::ListenAccept will emit for each accepted client socket. "PUBLIC EVENTS" describes it in detail
ErrorEvent is an optional event name that will be emitted whenever a serious problem occurs. Please see "PUBLIC EVENTS" for more details.
event() allows a session to change the events emitted by a wheel without destroying and re-creating the object. It accepts one or more of the events listed in "PUBLIC EVENTS". Undefined event names disable those events.
Ignore connections:
sub ignore_new_connections {
$_[HEAP]{tailor}->event( AcceptEvent => "on_ignored_accept" );
}
sub handle_ignored_accept {
# does nothing
}The ID() method returns the wheel's unique ID. It's useful for storing the wheel in a hash. All POE::Wheel events should be accompanied by a wheel ID, which allows the wheel to be referenced in their event handlers.
sub setup_listener {
my $wheel = POE::Wheel::ListenAccept->new(... etc ...);
$_[HEAP]{listeners}{$wheel->ID} = $wheel;
}POE::Wheel::ListenAccept emits a couple events.
AcceptEvent names the event that will be emitted for each newly accepted client socket. It is accompanied by three parameters:
$_[ARG0] contains the newly accepted client socket handle. It's up to the application to do something with this socket. Most use cases involve passing the socket to a POE::Wheel::ReadWrite constructor.
$_[ARG1] contains the accept() call's return value, which is often the encoded remote end of the remote end of the socket.
$_[ARG2] contains the POE::Wheel::ListenAccept object's unique ID. This is the same value as returned by the wheel's ID() method.
A sample AcceptEvent handler:
sub accept_state {
my ($client_socket, $remote_addr, $wheel_id) = @_[ARG0..ARG2];
# Make the remote address human readable.
my ($port, $packed_ip) = sockaddr_in($remote_addr);
my $dotted_quad = inet_ntoa($packed_ip);
print(
"Wheel $wheel_id accepted a connection from ",
"$dotted_quad port $port.\n"
);
# Spawn off a session to interact with the socket.
create_server_session($handle);
}ErrorEvent names the event that will be generated whenever a new connection could not be successfully accepted. This event is accompanied by four parameters:
$_[ARG0] contains the name of the operation that failed. This usually is 'accept', but be aware that it's not necessarily a function name.
$_[ARG1] and $_[ARG2] hold the numeric and stringified values of $!, respectively. POE::Wheel::ListenAccept knows how to handle EAGAIN (and system-dependent equivalents), so this error will never be returned.
$_[ARG3] contains the wheel's unique ID, which may be useful for shutting down one particular wheel out of a group of them.
A sample ErrorEvent event handler. This assumes the wheels are saved as in the "ID" example.
sub error_state {
my ($operation, $errnum, $errstr, $wheel_id) = @_[ARG0..ARG3];
warn "Wheel $wheel_id generated $operation error $errnum: $errstr\n";
delete $_[HEAP]{listeners}{$wheel_id};
}POE::Wheel describes the basic operations of all wheels in more depth. You need to know this.
POE::Wheel::ReadWrite for one possible way to handle clients once you have their sockets.
The SEE ALSO section in POE contains a table of contents covering the entire POE distribution.
None known.
Please see POE for more information about authors and contributors.