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A simple handler to provide Server Sent Events from Raku applications

Build Status


This sends out an event with the DateTime string every second

use EventSource::Server;
use HTTP::Server::Tiny;

my $supply = Supply.interval(1).map( { EventSource::Server::Event.new(type => 'tick', data => DateTime.now.Str) } );

my &es = EventSource::Server.new(:$supply);

HTTP::Server::Tiny.new(port => 7798).run(&es)

Or using Cro:

use EventSource::Server;

use Cro::HTTP::Router;
use Cro::HTTP::Server;

my $supply = Supply.interval(1).map( { EventSource::Server::Event.new(type => 'tick', data => DateTime.now.Str) } );

my $es = EventSource::Server.new(:$supply);

my $app = route {
    get -> {
        content 'text/event-stream', $es.out-supply;

my Cro::Service $tick = Cro::HTTP::Server.new(:host<localhost>, :port<7798>, application => $app);


react whenever signal(SIGINT) { $tick.stop; exit; }

And in some Javascript program somewhere else:

var EventSource = require('eventsource');

var v = new EventSource('');

v.addEventListener("tick", function(e) {

}, false);

See also the examples directory in this distribution.


This provides a simple mechanism for creating a source of Server Sent Events in a web server application.

The EventSource interface is implemented by most modern web browsers and provides a lightweight alternative to Websockets for those applications where only a uni-directional message is required (for example for notifications,)


Assuming you have a working installation of Rakudo with zef installed then you should be able to install this with:

zef install EventSource::Server

If you want to install this from a local copy substitute the distribution name for the path to the local copy.


This is quite a simple module but is fairly difficult to test well without bringing in a vast array of large and otherwise un-needed modules, so I won't be surprised there are bugs, similarly whilst I have tested for interoperability with the Javascript hosts that I have available to me I haven't tested against every known host that provides the EventSource interface.

So please feel free to report any problems (or make suggestions,) to https://github.com/jonathanstowe/EventSource-Server/issues

This is free software, please see the LICENCE file in the distribution.

© Jonathan Stowe 2017 - 2021