Breaking my blog embargo

I often find myself in the situation where I’ve not blogged for a long time which makes it difficult to write a new one, as if the long delay means the next blog has to be weighty and impressive.

I’ve realised this is an illusion. Nobody is sitting in wait for my next blog entry. Nobody else has noticed I’ve not blogged in ages. Only I know I’ve not blogged in ages. And I certainly shouldn’t care about what I think.

So I’m breaking my accidental self-imposed blog embargo with this mundane entry which says nothing of import.

If you were hoping for something of more consequence then I make no apology, though your hopes disprove my above realisation, which is irksome to say the least.

19/2/2011 2 Comments

The cost of free

Helienne Lindvall writes in the Guardian:

Cory Doctorow [will] cost you $25,000 (£15,800) to get him to speak at your conference…

But what does Doctorow speak about? Well, ironically, he’s a proponent of giving away content for free as a business model – and for years he’s been telling the music industry to adapt to it. Am I the only one to see the irony in this?

I don’t see the irony. This is exactly what Doctorow recommends. Give your content away and charge to perform it. Give your music away and charge for your gigs. I bet the content of his slides is creative commons, and I bet the recordings of this talks are creative commons even. But if watching a video of him isn’t enough for you and you want him in person, then you pay for it.

It seems that Helienne Lindvall does not understand even the basic ideas of free culture.

UPDATE: Helienne Lindvall seems to have been misinformed anyway, as per this tweet from Doctorow himself:

@helienne, I’m afraid you were badly misinformed. I don’t have a “booker”, I don’t charge anything like the sum quoted, most talks are free

UPDATE: Doctorow has since written an interesting article rebutting Lindvall.

27/9/2010 Add Comment

ipq.co: create dns records instantly

ipq.co is a new service I put together to lower the barrier for dns management. It’s the tinyurl of the dns world – provide an IP address and you get a random dns record for it (or you can choose your own, if it’s available).  Looking at other dns management systems, I was surprised this hadn’t been done before (and by how awful most of the dns interfaces are out there!)

I wrote it in Ruby using the Rails 3 framework, with the dns records being served by the PowerDNS MySQL back end (though I’ll likely be switching it to use a custom back end using my powerdns_pipe library for more flexibility).

We’re building a big new cloud system over at Brightbox and we’ve been thinking how to provide convenient dns records for our customers.  We already have some basic integration but the resulting records are quite a mouthful. ipq.co is just a bit of an experiment to explore other ways of solving the problem.  There has already been some discussion over on Hacker News about possible applications (and implications) of the service – I’m interesting in how people will use it.

I’ve got some plans for other features which I’ll be adding over the next few weeks, and then I’ll be selling it to Google for low 7 figures, so watch this space.

Wildcard IP lookups

You can now do wildcard IP lookups, as provided by the xip.io service, useful for development environments:

$ host whatever.10.0.0.5.ip.ipq.co

whatever.10.0.0.5.ip.ipq.co is an alias for 2rvxtx.ip.ipq.co.

2rvxtx.ip.ipq.co has address 10.0.0.5

New additional domain name

A donor has transferred ownership of a new domain for use with ipq.co.  So now, rather childishly, you can create instant dns records as subdomains of mypen.is:

$ host localhost.mypen.is
localhost.mypen.is has address 127.0.0.1




10/9/2010 8 Comments

LVM snapshot performance

The Linux Logical Volume Manager (LVM) supports creating snapshots of logical volumes (LV) using the device mapper. Device mapper implements snapshots using a copy on write system, so whenever you write to either the source LV or the new snapshot LV, a copy is made first.

So a write to a normal LV is just a write, but a write to a snapshotted LV (or an LV snapshot) involves reading the original data, writing it elsewhere and then writing some metadata about it all.

This quite obviously impacts performance, and due to device mapper having a very basic implementation, it is particularly bad.  My tests show synchronous sequential writes to a snapshotted LV are around 90% slower than writes to a normal LV.

(more…)

18/6/2010 6 Comments

Testing XML with rspec, xpath and libxml

I’m currently working with the virtualization API libvirt which uses XML to represent virtual machines and I’m generating this XML using Ruby.  I’m using rspec to test my code and wanted to test that my output was as I expected.  I started out with rspec-hpricot-matchers which worked fine until I started testing slightly more complex xml, which hpricot wasn’t handling well.

So I wrote a have_xml matcher using the rspec dsl which uses the libxml library to do the testing.  It’s so simple it’s not really worthy of a gem, so here it is (licensed under public domain).  The text check is optional and, to be honest, doesn’t belong here really.  It should be a separate matcher.


require 'libxml'

Spec::Matchers.define :have_xml do |xpath, text|
  match do |body|
    parser = LibXML::XML::Parser.string body
    doc = parser.parse
    nodes = doc.find(xpath)
    nodes.empty?.should be_false
    if text
      nodes.each do |node|
        node.content.should == text
      end
    end
    true
  end

  failure_message_for_should do |body|
    "expected to find xml tag #{xpath} in:\n#{body}"
  end

  failure_message_for_should_not do |response|
    "expected not to find xml tag #{xpath} in:\n#{body}"
  end

  description do
    "have xml tag #{xpath}"
  end
end

So, add that somewhere (usually spec/spec_helper.rb) and use it like this:


it "should include the xen_machine_id" do
  @xml.should have_xml('/domain/name', 'bb-example-001')
end

it "should include the network devices" do
  @xml.should have_xml "/domain/devices/interface[1]/ip[@address='1.2.3.4']"
  @xml.should have_xml "/domain/devices/interface[1]/mac[@address='aa:00:01:02:03:04']"
  @xml.should have_xml "/domain/devices/interface[1]/script[@path='/etc/xen/scripts/vif-bridge']"
  @xml.should have_xml "/domain/devices/interface[1]/source[@bridge='inetbr']"
end

6/4/2010 4 Comments

Chat Roulette: Eye Vagina

Chat Roulette is a web site that hooks you up to a random person. It streams their webcam video and audio to you, and your’s to them.  When you’re done, you click next and get another random person. That’s the whole thing.  It’s fun, for a short period of time.

Anyway, whilst holding my webcam to different parts of my body (if you ever use my webcam, wash your hands) I discovered that my eye, on its side, with the right lighting, and right shadows, and bad focus, through a webcam… looks kinda, possibly, a bit like girl bits.

It’s probably fair to say that, for a large proportion of the random strangers on Chat Roulette, the “Next” button is usually clicked in the hope of seeing a girl flashing some part of her body.

Combine these two seemingly unconnected facts together, and you get some of the reactions you see in my Eye Vagina video!  The music is “My Vagina” by NOFX. I edited out roughly 300 people jerking off.  The vid has had more than half a million hits on you tube. I’m expecting my share of their fat advertising profits any day now.

I recorded it using recordmydesktop and edited it using Pitivi (which actually had some very annoying audo sync problems I had to jump through hoops to avoid, which was a shame).

10/3/2010 2 Comments

Advertising and ad blocking

I’ve thought about advertising and ad-blockers a lot over the years, and the debate is getting some attention right now starting with a recent Ars Technica article, so I thought I’d put down some of my own thoughts on it.

Funding your content through advertising is hugely inefficient. Of the people who visit your site, usually only a tiny proportion click on (or notice) an advert, and only a tiny proportion of those then spends any money.  So a tiny, tiny proportion of your visitors give any money to your advertisers. So money filters down this system in tiny margins.  Then, at the bottom of the system, a tiny amount of the profits from the income covers the cost of advertising.  Then this money moves back up the system to you, usually via your advertising agent who takes a nice cut (I’ve heard Google pass as little as one twelfth onto the publisher in some cases).

And this doesn’t consider the costs of the advertiser choosing and designing the ad or the tonnes of bandwidth and gatrillions of CPU cycles used to serve the actual adverts.

It also does not consider externalities, such as pollution. Advertising is mind pollution. Advertising is designed to affect the behaviour of people for the benefit of the advertiser.  Why would anyone willingly expose themselves to something designed to steal their attention?

You might argue that advertising creates value – some viewers choose to buy when otherwise they wouldn’t have. But what of the huge proportion of people who just had their attention stolen? No value was created there.

Because not everyone is suckered in by it, advertising squanders billions of hours of attention every day to produce nothing.
(more…)

7/3/2010 21 Comments

Old sycamore tree

The sycamore tree in the garden of our new house had to come down after some of it’s huge branches started coming down in high winds.

13/2/2010 Add Comment

Xapian Fu: Full Text Indexing in Ruby

Xapian is an Open Source Search Engine Library written in C++. It has Ruby bindings, but they’re generated with SWIG, so they basically just mirror the C++ bindings – not very Ruby-like (and pretty ugly).

Being a self-confessed full text indexing nerd and a Ruby-lover, I wrote Xapian Fu: a library to provide access to Xapian that is more in line with “The Ruby Way”.

I started writing Xapian Fu exactly a year ago today but left it for a couple of months, then restarted work on it on the train on the way back from the 2009 Scotland on Rails conference.  Development was test driven, so it’s got an extensive test suite (using rspec).  Documentation is in rdoc and is quite detailed.  As of the latest version, it supports Ruby 1.9 too.

Xapian Fu basically gives you a Hash interface to Xapian – so you get a persistent Hash with full text indexing built in (and ACID transactions!).

Example

For example, create a database called example.db, put three documents into it and search them and print the results:

  require 'xapian-fu'
  include XapianFu
  db = XapianDb.new(:dir => 'example.db', :create => true,
                    :store => [:title, :year])
  db << { :title => 'Brokeback Mountain', :year => 2005 }
  db << { :title => 'Cold Mountain', :year => 2004 }
  db << { :title => 'Yes Man', :year => 2008 }
  db.flush
  db.search("mountain").each do |match|
    puts match.values[:title]
  end

There are of course a whole bunch more examples in the documentation.
(more…)

31/1/2010 1 Comment

Ruby’s case statement uses ===

I’ve not found this stated clearly enough elsewhere so I’m doing so myself.

Ruby’s case statement calls the === method on the argument to each of the when statements

So, this example:

case my_number
  when 6883
    :prime
end

Will execute 6883 === my_number

This is all fine and dandy, because the === method on a Fixnum instance does what you’d expect in this scenario.

However, the === method on the Fixnum class does something different. It’s an alias of is_a?

That is cute, because it allows you to do this:

case my_number
  when Fixnum
    "Easy to memorize"
  when Bignum
    "Hard to memorize"
  end

But it won’t work as you might expect in this scenario:

my_type = Fixnum
case my_type
  when Fixnum
    "Fixed number"
end

This won’t work because Fixnum === Fixnum returns false because the Fixnum class is not an instance of Fixnum.

My workaround for this is to convert it to a string first. Not sure if that’s the best solution, but it works for me(tm).

my_type = Fixnum
case my_type.to_s
  when "Fixnum"
    "Fixed number"
end

30/8/2009 9 Comments

Song In Code: Ramones, I wanna be sedated

Just the first verse:

go = Proc.new { sleep 24.hours }
self.wants :sedatation
begin ; nil ; end
case go ; where "no" ; nil ; end
self.wants :sedatation
self.get '/airport'
self.put '/airport/plane'
before self.insane? do
  3.times { hurry! }
end
return if self.can_control? :fingers
return if self.can_control? :brain
5.times { "no" }

I recorded me singing it, which is kinda stupid tbh.

I used mencoder to convert this to something Youtube found tasty. Like this:

mencoder -ss 15 -endpos 1:18 -vf pp=al:f,scale=480:360 -oac mp3lame -ovc lavc -lavcopts vcodec=libx264:mbd=1:vbitrate=2000 MOV01362.MPG -o MOV01362.x264

Also, pimp for another Geek/Ukelele project: Ukepedia, all 3 million Wikipedia articles one song at a time

21/8/2009 6 Comments

Boron Fights Grass

Boron Fights Grass

5/7/2009 Add Comment