Saturday, June 28, 2008

Itching my programming nerve

Photo: oreillygmt

I've just got back from the first ever commercial Erlang conference. Some 40 talks in two days all related in some way or other to Erlang. It was a chance to meet old friends, make new friends and connect people together in the hope that new synergy effects would arise.

The most exciting thing was the emergence of what I think might be the first killer applications written in Erlang. I might be wrong, but my gut feeling is that what Alexander Reinefeld showed us will be the first killer application in Erlang.

Only a few language nerds are interested in programming languages in their own right. Most people are more interested in what you can do with a programming language than with the underlying language. Thus is was with Ruby. Ruby on rails was the application that drew developers into Ruby. It made them want to learn Ruby so that they could easily build web applications.

Alexander Reinefeld told us about an Erlang implementation of the Wikipedia that not only has a stunningly beautiful architecture, but which outperforms the existing Wikipedia.

I'll talk about the Wikipedia implementation later in this posting, but it was not the only notable talk there were many other great talks.

Claes Vikström (Klacke) gave a great lecture which was a mixture of battle stories, history and what he was doing today.

Klacke is the master of the one-line throw-away remark - "and then I implemented a DBMS ... and a web server" this was the technical stuff, and on the business side
...then we started a company and made a whole lot of money...
At the end of his lecture Klacke said something like:
... so how come we have this great technology and people are just doing boring things and not writing stock exchanges ... there aren't any killer applications ...
Just as an aside Joel Reymont did stir up the Erlang mailing list with his announcement that he wanted to write an open source stock exchange as a publicity stunt, but this ran out in the sand. Perhaps later we can resurrect this idea, it would be a bit of fun.

The Wiki

Now for the fun stuff. Alexander Reinefeld video answered Klackes call for action and for a non-boring application as he described how he had implemented the Wikipedia on a new p2p system now called Scalaris.

Here's my version of his story:
  1. They make a peer to peer system based on the chord algorithm
  2. They added a replication later using the paxos algorithm
  3. They added a transaction layer
  4. The injected the wikipedia
  5. It went faster that the existing wikipedia
Applied to Wikipedia, Scalaris serves 2,500 transactions per second with just 16 CPUs, which is better than the public Wikipedia.
Alexander is a tall bespectacled academic who usually only turns up at academic conferences. He was very worried at the start of the talk when he was introduced as "Professor Reinefeld" I think he thought it would frighten people.

The system they described won an IEEE prize for scalable systems and was also presented at the Google conference on scalability. I asked Alexander why publicity about what they had done was so hard to find.
"I'm academic, we usually publish papers," he said.
He'd also said he'd started a company that "wasn't doing very well" (tip to VCs - check this one out and give the guy some help).

So my take on this is that this is one of the sexiest applications I've seen in many a year. I've been waiting for this to happen for a long while. The work is backed by quadzillion Ph.D's and is really good believe me.

On second thoughts don't believe me but check out the video lecture. You can also download the code.


When Alexander had blown my mind Jan Lehnardt popped up for the next section and blew it even further by presenting CouchDB - am I going mad are we seeing the emergence of two killer applications? This cannot be.

Jan Lehnardt has a presentation technique that is a joy to watch - it reminded me of why I love programming.

Jan communicates on two level simultaneously. His body language oozes enthusiasm - he waves his arms so fast and hops up and down so we think that he was either a helicopter in a previous life or that he wants to get a job as a windmill. Words tumble out of his mouth so fast that his tongue often trips over the end of his sentences and falls flat into the middle of his next sentence conveniently missing out the middle of the last sentence.

Check out the video and you'll see that I mean - You'll see Jan almost taking off as he impersonates a helicopter. For more information see the slides of the talk. You can download CouchDb from the Apache incubator site.

This style of lecturing is amazing. Jan communicates simultaneously on two entirely different level. His enthusiasm is received by the amygdala in the limbic system and his slides go via your eyes to the pre-frontal cortex for analytic processing.

So what was this great stuff the Jan was so enthusiastic about?

CouchDb - is an Erlang application that turns a Key-Value JSON store into a system with a RESTFUL interface that stores arbitrary data structures data in a way that fits nicely in with the Erlang system. When I got home I downloaded CouchDb and took a look, and there is was, nicely packaged with a Mochiweb server, the same server which is used by facebook for their comet web chat system.

Like most good ideas the CouchDB is deceptively simple. Once you've seen it you think - yes that's how it should be, how simple, how beautiful. But designing simple things is not easy it requires many false starts and takes a long time to get right. Hats off to Damien Katz for the initial design and to his collaborators, and thanks Jan for telling us about it.


Now it just so happens that both Jan Lehnardt and Alexander Reinefeld both live in Berlin, both are working with key-value stores (the details, vary) which are programmed in Erlang, both of them are working on what might be the next killer Erlang application and ... they have never met.

I introduced them and then stood back. Wow.

After a moment of shyness they changed to speaking German and Jan started bouncing up and down and speaking even faster than in English - this was getting dangerous - this time Jan did turn into a helicopter and narrowly missed causing an accident as he flew out of the room.

Going home

Klacke and I took the same flight back to Sweden the next day.

"That itched my programming nerve," said Klacke

"Precisely ..."


Denton Gentry said...

If you're looking to drum up publicity about Erlang, I would think that Facebook chat would be a great candidate ( It might not be a stunningly new application area for Erlang, but simply the fact that it is a production application for Facebook would be worth a lot of mileage.

Anonymous said...

I was at the erlang exchange and found both Reinefelds and CouchDBs my favourite two talks.

However I was a bit skeptical that a wikipedia clone would be a 'killer' app.

Wikipedia already exists, the one presented may be faster, but Wikipedia itself isnt particularly slow, neither are its well established clones. It may be a very useful learning tool and proof of concept, but 'killer app' to me describes something that crosses outside of the erlang world and there isnt an impetus to migrate however many million wikipedia users there are.

ejabberd, couchdb, simpledb and facebook chat are a lot closer to that title, in my opinion.

Joe Armstrong said...

[dale] - The wikipedia is "the icing on the cake." The interesting thing is not the icing, it's the cake.

Viktor Sovietov said...

It's so pity that my company wasn't able to participate this time. We would added some itching with scalable mobile gaming server (written on Erlang, of course), high performance Erlang clusters which bypass TCP to get latency between nodes as low as it possible and yet another distributed database, Hiero, that uses old fashioned, but also most proven method to store hierarchies used in MUMPS (ANSI M) databases. I expect a lot of interesting things to be occurred this year, thank you for great tool Joe! Erlang is one from few languages designed for real life apps. said...

I can only agree that Erlang is one of the few languages designed for real life apps. We addressed some of the issues that are out there with large file transfers, and came up with a neat solution with our Erlang web app called Streamfile. I hope this could be one "killer" app that could spread Erlang a bit more to the masses. For more info check:

Mono Groncho said...


I got here through (just random browsing really) and the post revived my interest in Erlang (first heard of it around 1998 during my undergrad). So you definitely got my nerve itching all right!

I've decided to learn Erlang (just for fun really) and found this to get me started:

Do you reckon that's a good one?