NAME

Plack::App::EventSource - EventSource/SSE for Plack

SYNOPSIS

use Plack::App::EventSource;
use Plack::Builder;

builder {
    mount '/events' => Plack::App::EventSource->new(
        handler_cb => sub {
            my ($conn, $env) = @_;

            $conn->push('foo');
            # or
            # $conn->push('foo', 'bar', 'baz');
            # or
            # $conn->push({id => 1, data => 'foo'});
            $conn->close;
        }
    )->to_app;

    mount '/' => $app;
};

DESCRIPTION

Plack::App::EventSource is an EventSource or Server Sent Events applications. EventSource is an alternative to WebSockets when there is no need for duplex communication. EventSource uses HTTP and is much simpler in implementation. Ideal for website notifications or read only update streams.

This library stays event loop agnostic, which means that you can use it with AnyEvent or POE or even just with a plain forking server.

Plack::App::Eventsource is a subclass of Plack::Component, inheriting all its methods. You should only have to know about the to_app method.

Options

handler_cb

The main application entry point. It is called with Plack::App::EventSource::Connection and PSGI $env parameters.

handler_cb => sub {
    my ($conn, $env) = @_;

    $conn->push('hi');
    $conn->close;
}

headers

Additional response headers. This is useful when you want to add Access Control headers:

headers => [
    'Access-Control-Allow-Origin' : 'http://localhost:5000',
    'Access-Control-Allow-Credentials' : 'true'
]

HOWTOs

Client support

It is recommended to use EventSource with polyfills to enable them in browsers that don't support SSE. This does not need any server changes, which is very handy. Take a look at EventSource.js and jquery.eventsource.

Sending cookies to another domain

Set CORS headers:

headers => [
    'Access-Control-Allow-Origin' : 'http://original-domain',
    'Access-Control-Allow-Credentials' : 'true'
]

If you try to set Origin to * some browsers will complain. So make sure to set the correct original domain.

When connecting to EventSource on the client side pass withCredentials option:

var es = new EventSource("http://another-domain", {
    withCredentials: true
});

Nginx proxy

location /events {
        proxy_pass http://backend;
        proxy_buffering off;
        proxy_cache off;
        proxy_set_header Host $host;
        proxy_set_header Connection '';
        proxy_http_version 1.1;
        chunked_transfer_encoding off;
}

CREDITS

Jakob Voss (nichtich)

AUTHOR

Viacheslav Tykhanovskyi, <viacheslav.t@gmail.com>

COPYRIGHT AND LICENSE

Copyright (C) 2015-, Viacheslav Tykhanovskyi

This program is free software, you can redistribute it and/or modify it under the terms of the Artistic License version 2.0.

This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.