From 0afbfaee75e8480e8e0ed0a3bbd3749a4756f727 Mon Sep 17 00:00:00 2001
From: franck cuny <franck@lumberjaph.net>
Date: Fri, 10 Sep 2010 23:25:10 +0200
Subject: initial import

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+---
+layout: post
+category: perl
+title: presque, a Redis / Tatsumaki based message queue
+---
+
+"presque":http://github.com/franckcuny/presque/tree/ is a small message queue service build on top of "redis":http://code.google.com/p/redis/ and "Tatsumaki":http://search.cpan.org/perldoc?Tatsumaki. It's heavily inspired by "RestMQ":http://github.com/gleicon/restmq and "resque":http://github.com/defunkt/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
+
+h3. Overview
+
+resque need a configuration file, writen in YAML that contains the host and port for the Redis server.
+
+{% highlight yaml %}
+redis:
+    host: 127.0.0.1
+    port: 6379
+{% endhighlight %}
+
+Let's start the server:
+
+{% highlight bash %}
+$ plackup app.psgi --port 5000
+{% endhighlight %}
+
+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 :
+
+{% highlight bash %}
+curl -X POST "http://localhost:5000/q/foo" -d '{"foo":"bar", "foo2":"bar" }'
+{% endhighlight %}
+
+and fetching the job:
+
+{% highlight bash %}
+curl "http://localhost:5000/q/foo"
+{% endhighlight %}
+
+When a job is fetched, it's removed from the queue.
+
+h3. A basic worker
+
+I've also uploaded "presque::worker":http://github.com/franckcuny/presque-worker/tree/ to github. It's based on "AnyEvent::HTTP":http://search.cpan.org/perldoc?AnyEvent::HTTP and "Moose":http://search.cpan.org/perldoc?Moose. Let's write a basic worker using this class:
+
+{% highlight 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;
+{% endhighlight %}
+
+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.
+
+h3. The future
+
+I plan to add support for "websocket":http://en.wikipedia.org/wiki/WebSocket, and probably "XMPP":http://en.wikipedia.org/wiki/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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