jod.al

10 years of Mopidy

2019-12-23T00:00:00+00:00
Ten years ago today, on December 23, 2009, Mopidy was born. While chatting with my friend and then-colleague Johannes Knutsen, we came up with the idea of building an MPD server that could play music from Spotify instead of local files.</p>
This is the story of the first decade of Mopidy.</p>
pathlib and paths with arbitrary bytes

2019-12-10T00:00:00+00:00
The pathlib</code></a> module was added to the standard library in Python 3.4 and is one of the many nice improvements that Python 3 has gained over the past decade. In three weeks, Python 3.5 will be the oldest version of Python that still receives security patches. This means that the presence of pathlib</code> can soon be taken for granted on all Python installations, and the quest towards replacing os.path</code> can begin for real.</p>
In this post, I’ll have a look at how pathlib</code> can be used to handle file paths containing arbitrary bytes, as this is valid on most file systems.</p>

Pykka 2.0 released with better ergonomics and performance improvements
2019-05-07T00:00:00+00:00
I’ve finally released Pykka</a> 2.0, the
first major update to Pykka in almost six years.</p>
Pykka is a Python implementation of the actor model. The actor model
introduces some simple rules to control the sharing of state and cooperation
between execution units, which makes it easier to build concurrent
applications.</p>
Pykka 2.0 is a major release because it is backwards incompatible in several
minor ways. However, the backwards incompatible changes should only affect
quite narrow use cases.
Mopidy and its extensions,
which is the largest open source ecosystem I know of that uses Pykka,
runs unmodified on Pykka 2.0.</p>
In this blog post I’ll go through some of the more important improvements in
2.0.</p>


Mopidy-MPRIS 2.0 released
2018-12-07T00:00:00+00:00
I’ve released Mopidy-MPRIS</a> 2.0, the
first major update to Mopidy-MPRIS in about 3.5 years.</p>
Mopidy-MPRIS is a Mopidy extension that makes Mopidy</a>
controllable from other programs on the same machine through D-Bus. This makes
it possible to control Mopidy from various widgets in GNOME/KDE/etc, as well as
with keyboard media keys.</p>


Four years of JavaScript churn: Mopidy.js 1.0
2018-12-02T00:00:00+00:00
Yesterday, I released v1.0.0 of the Mopidy.js</a>
JavaScript library. Even though the library serves as the basis for most Mopidy
web clients and has been in active use since 2013, this was the first release
in almost four years.</p>
Four years is quite a long time in the world of JavaScript.</p>


Bringing the Mopidy music server to the browser
2017-08-26T00:00:00+00:00
Note: This is a blog post draft that was originally written in January 2013,
left unattended for 1689 days, and rediscovered and published unedited in
August 2017.</p>
During the five years since Mopidy entered the browser with its HTTP JSON-RPC
API and the Mopidy.js JavaScript library, many successful Mopidy web
clients have been built on top of this foundation. The APIs themselves have
survived the test of time and have required minimal maintenance, just as I
hoped when implementing the APIs back in November 2012.</p>

Mopidy</a> is a music server written in
Python. It plays music from various sources, including local disk and Spotify.
Mopidy can be remote-controlled by, among others, MPD</abbr> clients.</p>
In Mopidy 0.10, released in the middle of December, we added an HTTP frontend.
The HTTP frontend takes Mopidy’s full core API and makes it available from
JavaScript in the browser. This means that you now can make your own web
clients for Mopidy in JavaScript, and Wouter van Wijk has already started on
his client</a> (updated
link</em>).</p>
I’d like to write a bit about how we made the HTTP client.</p>


netsgiro: a parser and builder for AvtaleGiro and OCR Giro files
2017-05-21T00:00:00+00:00
Today I released the first stable release of
netsgiro</a> to
PyPI</a>. netsgiro is a Python 3.4+ library
for parsing and building Nets</a> “OCR” files.</p>
AvtaleGiro is a direct debit solution that is in widespread use in Norway, with
more than 15 000 companies offering it to their customers. OCR Giro is used by
Nets and Norwegian banks to update payees on recent deposits to their bank
accounts. In combination, AvtaleGiro and OCR Giro allows for a high level of
automation of invoicing and payment processing.</p>
The “OCR” file format and file format name originates in days when giro
payments were delivered on paper to your bank and then processed either
manually or using optical character recognition, OCR. I’m not sure how old the
format is, but some of the examples in the OCR Giro specification use dates in
1993, and the specification changelog starts in 1999 and ends in 2003. A couple
of decades later, the file format is still in daily use by Nets’ AvtaleGiro
and OCR Giro services. In other words, I have high hopes that this will be a
very stable open source project requiring minimal maintenance efforts.</p>


March and April contributions
2016-04-30T00:00:00+00:00
The following is a short summary of my open source work in March and April,
almost like in previous months, except that I haven’t spent as much time as
previously on Open Source the last two months.</p>


February contributions
2016-03-01T00:00:00+00:00
The following is a short summary of my open source work in February, just like
in</a>
previous</a>
months</a>.</p>


A guide to poor API management
2016-02-18T00:00:00+00:00
This is the story of libspotify, as experienced by a Spotify customer and
libspotify developer for six years.</p>


January contributions
2016-02-01T00:00:00+00:00
The following is a short summary of my open source work in January, just like I
did back in November</a> and
December</a>.</p>


December contributions
2016-01-01T00:00:00+00:00
The following is a short summary of my open source work in December, following
up on my first report in November</a>.</p>


November contributions
2015-11-30T00:00:00+00:00
The following is a short summary of my open source work in November. My hope is
that keeping better track of what I’m doing will help me reflect on how I spend
my time, and help me to focus my efforts better.</p>


Building ARM Debian packages with pbuilder
2015-03-08T00:00:00+00:00
The goal of this post is to help myself reproduce this pbuilder setup in the
future. If you find it useful too, then that’s great.</em></p>
Building ARM packages on older ARM devices like the Raspberry Pi 1 is slow, so
I want to use a single amd64 machine to build Debian packages for all my target
platforms:</p>

amd64,</li>
i386,</li>
armel/ARMv4+ (e.g. Debian on Raspberry Pi 1),</li>
armhf/ARMv6+ (Raspbian), and</li>
armhf/ARMv7+ (e.g. Debian/Ubuntu on Raspberry Pi 2, Odroid C1, etc.).</li>
</ul>
Preferably, I want to build the packages for the current Debian stable, which
at the time of writing is wheezy, so that they’ll work for as many users as
possible.</p>


Debian packaging of Mopidy
2014-10-28T00:00:00+00:00
My first upload to Debian as a Debian Maintainer, Mopidy 0.19.4-3, landed in
Debian testing today, well in time for the upcoming freeze.</p>
The new version adjusts the LSB facilities the sysvinit script depends on, to
make sure that DNS lookups, DBus (used by Mopidy-MPRIS), and Avahi (used for
Zeroconf service publishing) are available before Mopidy starts.</p>


pyspotify v2.0.0b1 released, with new event loop and audio sinks
2014-04-24T00:00:00+00:00
pyspotify</a> 2.x is a full rewrite of pyspotify.
While pyspotify 1.x is a CPython C extension, pyspotify 2.x uses
CFFI</a> to make 100% of the libspotify C library
available from Python. It works on CPython 2.7 and 3.2+, as well as PyPy 2.1+.</p>


Comics v2.3.0 released with better mobile support
2014-04-07T00:00:00+00:00
Version 2.3.0 of my comics aggregator</a> is now
released. As always, dependencies have been updated, including the routine
Django upgrade from Django 1.5 to 1.6, just in time for the upcoming 1.7
release. The largest change this time around is the move from Bootstrap 2 to 3,
which includes a refreshed, flatter design and lots of tweaking to make Comics
both look good and work nicely on mobile devices, something it didn’t use to
do.</p>


New Python wrapper for libspotify
2014-02-14T00:00:00+00:00
Today, after about nine months of working on it now and then, I uploaded the
first alpha release of pyspotify 2.0</a> to
PyPI</a>.</p>
pyspotify provides a Python interface to Spotify’s</a>
online music streaming service. With it you can access music metadata, search
in Spotify’s library of 20+ million tracks, manage your Spotify playlists, and
play music from Spotify. All from your own Python applications.</p>


Mopidy packaged in Debian and Ubuntu
2013-12-28T00:00:00+00:00
Looking back to my last post from September, my goal was to have
the music server Mopidy</a> packaged in Debian by the end
of the year and in Ubuntu in time for the 14.04 LTS release in April. As of
yesterday, Mopidy 0.17.0 is a part of Debian
unstable</a> and Ubuntu
trusty</a>, just a few days after
Mopidy’s fourth anniversary on December 23.</p>


Pykka packaged in Debian and Ubuntu
2013-09-03T00:00:00+00:00
The Python actor library Pykka</a> is now packaged as
python-pykka</code> and python3-pykka</code> in
Debian unstable</a> and
Ubuntu saucy</a>, soon to be
Ubuntu 13.10. In a few more days, the packages will be probably be available in
Debian testing as well.</p>


Mopidy hosted by Rackspace
2013-07-22T00:00:00+00:00
A week ago Jesse Noller
tweeted</a> that
Rackspace</a> would provide free Rackspace cloud
accounts for open source projects. It only took a couple of hours from I first
mailed Jesse to we had two servers up and running.</p>


Pykka v1.2.0 with eventlet support and future transformations
2013-07-18T00:00:00+00:00
Pykka</a> v1.2.0 is now available from PyPI, GitHub, and
APT</a>. It’s about half a year since the previous
release, during which no serious bugs have been found.</p>


Comics v2.2.0 released with Django 1.5 support
2013-07-07T00:00:00+00:00
Version 2.2.0 of my comics aggregator is now released. It features a general
upgrade of dependencies, including the move from Django 1.4 to Django 1.5, and
a lot of updates to comic crawlers.</p>


Router setup for native IPv6 from Get.no
2012-09-16T00:00:00+00:00
As of June, the large Norwegian ISP Get</a> let most
customers sign up for a native IPv6 test program.</p>
The only information Get give you when you sign up to their IPv6 test program,
is that they:</p>

use DHCPv6 to delegate addresses and prefixes to the customer,</li>
SLAAC (Stateless Address Autoconfiguration) is not supported, and</li>
you’ll get a /60 prefix, i.e. 16 prefixes of size /64.</li>
</ul>


How to fail a test on uncaptured AJAX requests
2012-06-15T00:00:00+00:00
Recently, the tests for a frontend web project I’m working on started to become
more and more troublesome. Full hangs in the middle of a test run became a
frequent issue, destroying my precious coding flow.</p>


Speeding up a Django web site without touching the code
2011-10-19T00:00:00+00:00
I’ve recently been tweaking my server setup for a Django 1.3 web site with the
goal of making it a bit faster. Of course, there is a lot of speed to gain by
improving e.g. the number of database queries needed to render a web page, but
the server setup also has an effect on the web site performance. This is a log
of my findings.</p>


Traversable attributes in Pykka
2011-10-06T00:00:00+00:00
In Pykka</a> 0.13–which was released almost two
weeks ago–traversing the attributes of an actor is about 8.3 times faster than
it used to be. To paraphrase Apple: “8.3X faster. That’s amazing!” (Update:
This was written a couple of hours before the news of Jobs’ passing arrived.
May he continue to inspire us.)</em></p>
So, what is “traversable attributes”? Let’s take a few steps back.</p>


Hva alle utviklere må vite om tegnsettenkoding
2011-09-08T00:00:00+00:00
English: This is slides and video from the Norwegian lightning presentation
on character encoding I did at the JavaZone 2011 conference today.</em></p>
Takk for nok en knall konferanse :-)</p>
Her er slidene mine</a>
fra lyntalen om tegnsettenkoding jeg holdt på JavaZone 2011 i dag.
PDF-versjon</a> er også
tilgjengelig, by popular demand.</p>


pyspotify 1.2 released
2011-06-08T00:00:00+00:00
pyspotify is a Python wrapper for
libspotify</a>, which give
developers access to the Spotify</a> music streaming
service.</p>
Today, I tagged pyspotify 1.2 at GitHub</a>
and pushed the new release to
PyPI</a>. I’ve also made deb packages
of libspotify and pyspotify available at
apt.mopidy.com</a>.</p>


Log from the debugging of a segfault
2011-05-24T00:00:00+00:00
The following is a cleaned up log I wrote for myself while debugging a bug.
Writing a log while working helps me keep track of the debugging effort in case
I’m interrupted (life, sleep, work, etc.). It also requires me to explain all
findings to myself in fully spelled out sentences, making my thoughts
considerably easier to follow.</em></p>
In addition to serving as an example of a personal debug log, I hope it can be
useful as an introduction to debugging segfaults or other low-level bugs.</em></p>


FizzBuzz in Haskell
2011-03-31T00:00:00+00:00
I’ve recently started reading the free Haskell tutorial Learn You A Haskell
for Great Good!</a> while commuting. So far I’ve
enjoyed the tutorial, and I’ve had a couple moments where I’ve smiled to myself
on the bus due to typeclasses, etc., which I guess isn’t quite normal behaviour
among the general population ;-)</p>
I just discovered that the tutorial is going to be released as a book in a
couple of weeks. You should definitely pick it up if you’re interested in
learning a different programming language.</p>


Pykka, and porting Pykka to Python 3
2011-03-29T00:00:00+00:00
This is somewhat of an introduction to Pykka</a>,
a Python library implementing the actor model, which I’ve been working on now
and then since November. And it’s still just 300 lines of code!</p>
The goal of the actor model is to make it easier to develop concurrent programs
by removing all shared state and use messaging for all communication. Removing
shared state and doing lots of messaging doesn’t make anything easier by
itself, but it avoids common problems in concurrent programs like proper lock
usage and data corruption (due to the absence of proper lock usage). Also, I
believe the actor model makes it easier to reason about concurrent programs,
which is a nice property since software development often feels like 10%
development and 91% debugging.</p>


multiprocessing.Connection is not free
2011-03-20T00:00:00+00:00
I’ve
previously written</a>
about how to wrap multiprocessing.Connection</code> objects in a class that makes
Connection</code> objects picklable, and thus transferable over another
Connection</code>. That approach is still valid, but don’t use it–or Connection</code>
objects at all–for lots of use-once-and-throw-away connections.</p>


Traits in Python using multiple inheritance
2011-03-15T00:00:00+00:00
As you probably know, if a class needs to handle two mostly unrelated concerns, the
class should probably be split into two. This way, your will achieve
higher cohesion</a> in your
code, which is generally considered a good thing. Though, there are times where
you need to address two mostly unrelated concerns in a single class.</p>
The Scala programming language has a concept they call
traits</a>. Scala traits can be compared to
Java interfaces, except that Scala traits may be partially or fully
implemented, like abstract classes. As with Java interfaces, you can mixin</em>
multiple traits in a class. If any of the traits has colliding method
signatures, the last trait mixed in overrides the earlier ones. Just as with
regular inheritance and interfaces, the class must</em> implement any methods that
has not been implemented by the traits, and may</em> override any methods that
already has been implemented.</p>


Pickling multiprocessing Connection objects
2011-03-06T00:00:00+00:00
For safe message-based communication between threads and processes in Python, I
tend to use
multiprocessing</a>’s
Queue</code> and Pipe</code>. A pattern often seen is using a queue for sending messages
from multiple producers to a single consumer.</p>
When a producer wants a response to its message, I create a Pipe</code> and
piggy-back one end of the Pipe</code> (a Connection</code> object) to the message. I use
Python dicts as messages, and use the string “reply_to” as the dictionary key
for the connection objects.</p>
When the queue consumer processes a message, it doesn’t know who the sender is
or how to reach him. Though, if the message has an attached Connection</code>
object, the consumer can–almost magically–respond to the sender, across
thread and process boundaries.</p>
All good? Nope.</p>