NAME
Dancer2::Plugin::WebSocket - add a websocket interface to your Dancers app
VERSION
version 0.1.1
SYNOPSIS
bin/app.psgi:
#!/usr/bin/env perl
use strict;
use warnings;
use FindBin;
use lib "$FindBin::Bin/../lib";
use Plack::Builder;
use MyApp;
builder {
mount( MyApp->websocket_mount );
mount '/' => MyApp->to_app;
}config.yml:
plugins:
WebSocket:
# default values
serializer: 0
mount_path: /ws
MyApp.pm:
package MyApp;
use Dancer2;
use Dancer2::Plugin::WebSocket;
websocket_on_message sub {
my( $conn, $message ) = @_;
$conn->send( $message . ' world!' );
};
get '/' => sub {
my $ws_url = websocket_url;
return <<"END";
<html>
<head><script>
var urlMySocket = "$ws_url";
var mySocket = new WebSocket(urlMySocket);
mySocket.onmessage = function (evt) {
console.log( "Got message " + evt.data );
};
mySocket.onopen = function(evt) {
console.log("opening");
setTimeout( function() {
mySocket.send('hello'); }, 2000 );
};
</script></head>
<body><h1>WebSocket client</h1></body>
</html>
END
};
true;DESCRIPTION
Dancer2::Plugin::WebSocket provides an interface to Plack::App::WebSocket
and allows to interact with the webSocket connections within the Dancer app.
Plack::App::WebSocket, and thus this plugin, requires a plack server that supports the psgi streaming, nonblocking and io. Twiggy is the most popular server that fits the bill.
CONFIGURATION
-
serializer
If serializer is set to a
truevalue, messages will be assumed to be JSON objects and will be automatically encoded/decoded using a JSON::MaybeXS serializer. If the value ofserialieris a hash, it'll be passed as arguments to the JSON::MaybeXS constructor.plugins: WebSocket: serializer: utf8: 1 allow_nonref: 1By the way, if you want the connection to automatically serialize data structures to JSON on the client side, you can do something like
var mySocket = new WebSocket(urlMySocket); mySocket.sendJSON = function(message) { return this.send(JSON.stringify(message)) }; // then later... mySocket.sendJSON({ whoa: "auto-serialization ftw!" }); -
mount_path
Path for the websocket mountpoint. Defaults to
/ws.
PLUGIN KEYWORDS
In the various callbacks, the connection object that is passed is a Plack::App::WebSocket::Connection object augmented with the Dancer2::Plugin::WebSocket::Connection role.
websocket_on_open sub { ... }
websocket_on_open sub {
my( $conn, $env ) = @_;
...;
};Code invoked when a new socket is opened. Gets the new
connection
object and the Plack
$env hash as arguments.
websocket_on_close sub { ... }
websocket_on_close sub {
my( $conn ) = @_;
...;
};Code invoked when a new socket is opened. Gets the connection object as argument.
websocket_on_error sub { ... }
websocket_on_error sub {
my( $env ) = @_;
...;
};Code invoked when an error is detected. Gets the Plack
$env hash as argument and is expected to return a
Plack triplet.
If not explicitly set, defaults to
websocket_on_error sub {
my $env = shift;
return [
500,
["Content-Type" => "text/plain"],
["Error: " . $env->{"plack.app.websocket.error"}]
];
};websocket_on_message sub { ... }
websocket_on_message sub {
my( $conn, $message ) = @_;
...;
};Code invoked when a message is received. Gets the connection object and the message as arguments.
Note that while websocket_on_message fires for all messages receives, you can
also be a little more selective. Indeed, each connection, being a Plack::App::WebSocket::Connection
object, can have its own (multiple) handlers. So you can do things like
websocket_on_open sub {
my( $conn, $env ) = @_;
$conn->on( message => sub {
my( $conn, $message ) = @_;
warn "I'm only being executed for messages sent via this connection";
});
};websocket_url
Returns the full url of the websocket mountpoint.
# assuming host is 'localhost:5000'
# and the mountpoint is '/ws'
print websocket_url; # => ws://localhost:5000/wswebsocket_mount
Returns the mountpoint and the Plack app coderef to be
used for mount in app.psgi. See the SYNOPSIS.
GOTCHAS
It seems that the closing the socket causes Google's chrome to burp the following to the console:
WebSocket connection to 'ws://...' failed: Received a broken close frame containing a reserved status code.
Firefox seems to be happy, though. The issue is probably somewhere deep in AnyEvent::WebSocket::Server. Since the socket is being closed anyway, I am not overly worried about it.
SEE ALSO
This plugin is nothing much than a sugar topping atop Plack::App::WebSocket, which is itself AnyEvent::WebSocket::Server wrapped in Plackstic.
Mojolicious also has nice WebSocket-related offerings. See Mojolicious::Plugin::MountPSGI or http://mojolicious.org/perldoc/Mojolicious/Guides/Cookbook#Web-server-embedding. (hi Joel!)
AUTHOR
Yanick Champoux yanick@cpan.org
COPYRIGHT AND LICENSE
This software is copyright (c) 2017 by Yanick Champoux.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
