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[[http://github.com/franckcuny/presque/tree/][presque]] is a small
message queue service build on top of
[[http://code.google.com/p/redis/][redis]] and
[[http://search.cpan.org/perldoc?Tatsumaki][Tatsumaki]]. It's heavily
inspired by [[http://github.com/gleicon/restmq][RestMQ]] and
[[http://github.com/defunkt/resque][resque]].
- Communications are done in JSON over HTTP
- Queues and messages are organized as REST resources
- A worker can be writen in any language that make a HTTP request and
read JSON
- Thanks to redis, the queues are persistent
** Overview
resque need a configuration file, writen in YAML that contains the host
and port for the Redis server.
#+BEGIN_EXAMPLE
redis:
host: 127.0.0.1
port: 6379
#+END_EXAMPLE
Let's start the server:
#+BEGIN_EXAMPLE
% plackup app.psgi --port 5000
#+END_EXAMPLE
The applications provides some HTTP routes:
- */*: a basic HTML page with some information about the queues
- */q/*: REST API to get and post job to a queue
- */j/*: REST API to get some information about a queue
- */control/*: REST API to control a queue (start or stop consumers)
- */stats/*: REST API to fetch some stats (displayed on the index page)
Queues are created on the fly, when a job for an unknown queue is
inserted. When a new job is created, the JSON send in the POST will be
stored "as is". There is no restriction on the schema or the content of
the JSON.
Creating a new job simply consist to :
#+BEGIN_EXAMPLE
% curl -X POST "http://localhost:5000/q/foo" -d '{"foo":"bar", "foo2":"bar" }'
#+END_EXAMPLE
and fetching the job:
#+BEGIN_EXAMPLE
% curl "http://localhost:5000/q/foo"
#+END_EXAMPLE
When a job is fetched, it's removed from the queue.
** A basic worker
I've also pushed
[[http://git.lumberjaph.net/p5-presque-worker.git/][presque::worker]].
It's based on
[[http://search.cpan.org/perldoc?AnyEvent::HTTP][AnyEvent::HTTP]] and
[[http://search.cpan.org/perldoc?Moose][Moose]]. Let's write a basic
worker using this class:
#+BEGIN_SRC perl
use strict;
use warnings;
use 5.012; # w00t
package simple::worker;
use Moose;
extends 'presque::worker';
sub work {
my ($self, $job) = @_;
say "job's done";
...; # yadda yadda!
return;
}
package main;
use AnyEvent;
my $worker =
simple::worker->new(base_uri => 'http://localhost:5000', queue => 'foo');
AnyEvent->condvar->recv;
#+END_SRC
A worker have to extends the presque::worker class, and implement the
method /work/. When the object is created, the class check if this
method is avalaible. You can also provide a =fail= method, which will be
called when an error occur.
** The future
I plan to add support for
[[http://en.wikipedia.org/wiki/WebSocket][websocket]], and probably
[[http://en.wikipedia.org/wiki/Xmpp][XMPP]]. More functionalities to the
worker too: logging, forking, handling many queues, ... I would like to
add priorities to queue also, and maybe scheluding job for a given date
(not sure if it's feasable with Redis).
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