WebSocket server for AnyEvent
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AnyEvent::WebSocket::Server - WebSocket server for AnyEvent


use AnyEvent::Socket qw(tcp_server);
use AnyEvent::WebSocket::Server;

my $server = AnyEvent::WebSocket::Server->new();

my $tcp_server;
$tcp_server = tcp_server undef, 8080, sub {
    my ($fh) = @_;
    $server->establish($fh)->cb(sub {
        my $connection = eval { shift->recv };
        if($@) {
            warn "Invalid connection request: $@\n";
        $connection->on(each_message => sub {
            my ($connection, $message) = @_;
            $connection->send($message); ## echo
        $connection->on(finish => sub {
            undef $connection;


This class is an implementation of the WebSocket server in an AnyEvent context.

  • Currently this module supports WebSocket protocol version 13 only. See RFC 6455 for detail.


$server = AnyEvent::WebSocket::Server->new(%args)

The constructor.

Fields in %args are:

handshake => CODE (optional)

A subroutine reference to customize the WebSocket handshake process. You can use this option to validate and preprocess the handshake request and customize the handshake response.

For each request, the handshake code is called like

($response, @other_results) = $handshake->($request, $default_response)

where $request is a Protocol::WebSocket::Request object, and $default_response is a Protocol::WebSocket::Response object. The $handshake code must return $response. @other_results are optional.

The return value $response is the handshake response returned to the client. It must be either a Protocol::WebSocket::Response object, or a string of a valid HTTP response (including the Status-Line, the Headers and the Body).

The argument $default_response is a Protocol::WebSocket::Response valid for the given $request. If you don't need to manipulate the response, just return $default_response. That is,

handshake => sub { $_[1] }

is the minimal valid code for handshake.

In addition to $response, you can return @other_results if you want. Those @other_results can be obtained later from the condition variable of establish() method.

If you throw an exception from $handshake code, we think you reject the $request. In this case, the condition variable of establish() method croaks.

validator => CODE (optional)

This option is only for backward compatibility. Use handshake option instead. If handshake option is specified, this option is ignored.

A subroutine reference to validate the incoming WebSocket request. If omitted, it accepts the request.

The validator is called like

@other_results = $validator->($request)

where $request is a Protocol::WebSocket::Request object.

If you reject the $request, throw an exception.

If you accept the $request, don't throw any exception. The return values of the $validator are sent to the condition variable of establish() method.

ssl_key_file => FILE_PATH (optional)

A string of the filepath to the SSL/TLS private key file in PEM format. If you set this option, you have to set ssl_cert_file option, too.

If this option or ssl_cert_file option is set, AnyEvent::WebSocket::Server encrypts the WebSocket streams with SSL/TLS.

ssl_cert_file => FILE_PATH (optional)

A string of the filepath to the SSL/TLS certificate file in PEM format.

The file may contain both the certificate and corresponding private key. In that case, ssl_key_file may be omitted.

If this option is set, AnyEvent::WebSocket::Server encrypts the WebSocket streams with SSL/TLS.

max_payload_size => INT (optional)

The maximum payload size for received frames. Currently defaults to whatever Protocol::WebSocket defaults to. Note that payload size for sent frames are not limited.


$conn_cv = $server->establish($fh)

Establish a WebSocket connection to a client via the given connection filehandle.

$fh is a filehandle for a connection socket, which is usually obtained by tcp_server() function in AnyEvent::Socket.

Return value $conn_cv is an AnyEvent condition variable.

In success, $conn_cv->recv returns an AnyEvent::WebSocket::Connection object and @other_results returned by the handshake process. In failure (e.g. the client sent a totally invalid request or your handshake process threw an exception), $conn_cv will croak an error message.

($connection, @other_results) = eval { $conn_cv->recv };

## or in scalar context, it returns $connection only.
$connection = eval { $conn_cv->recv };

if($@) {
    my $error = $@;

You can use $connection to send and receive data through WebSocket. See AnyEvent::WebSocket::Connection for detail.

Note that even if $conn_cv croaks, the connection socket $fh remains intact. You can communicate with the client via $fh unless the client has already closed it.

$conn_cv = $server->establish_psgi($psgi_env, [$fh])

The same as establish() method except that the request is in the form of PSGI environment.

$psgi_env is a PSGI environment object obtained from a PSGI server. $fh is the connection filehandle. If $fh is omitted, $psgi_env->{"psgix.io"} is used for the connection (see PSGI::Extensions).


handshake option

The following server accepts WebSocket URLs such as ws://localhost:8080/2013/10.

use AnyEvent::Socket qw(tcp_server);
use AnyEvent::WebSocket::Server;

my $server = AnyEvent::WebSocket::Server->new(
    handshake => sub {
        my ($req, $res) = @_;
        ## $req is a Protocol::WebSocket::Request
        ## $res is a Protocol::WebSocket::Response

        ## validating and parsing request.
        my $path = $req->resource_name;
        die "Invalid format" if $path !~ m{^/(\d{4})/(\d{2})};
        my ($year, $month) = ($1, $2);
        die "Invalid month" if $month <= 0 || $month > 12;

        ## setting WebSocket subprotocol in response
        return ($res, $year, $month);

tcp_server undef, 8080, sub {
    my ($fh) = @_;
    $server->establish($fh)->cb(sub {
        my ($conn, $year, $month) = eval { shift->recv };
        if($@) {
            my $error = $@;
            error_response($fh, $error);
        $conn->send("You are accessing YEAR = $year, MONTH = $month");
        $conn->on(finish => sub { undef $conn });



AnyEvent-based WebSocket client implementation.


Minimalistic stand-alone WebSocket server. It uses its own event loop mechanism.


Stand-alone WebSocket server and client implementation using IO::Async


Toshio Ito, <toshioito at cpan.org>


mephinet (Philipp Gortan)




Graham Ollis (plicease) - author of AnyEvent::WebSocket::Client


Copyright 2013 Toshio Ito.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.