London, Cambridge, Amsterdam – Stack Overflow Dev Days in Europe

It is the day after my last talk at the Stack Overflow Dev Days Tour and I am very happy that I was part of this experience. If you haven't heard of it, Stack Overflow is a Question and Answer site backed by Joel Spolsky that is agnostic as to what kind of technology you need help with. It is obscenely successful for its age and it was great to be able to talk to a lot of developers that had never heard of the offers YDN has, or already have a fixed idea of what they want to use and why. I love a challenge, me :)

With this in mind, my talks for the London, Cambridge, and Amsterdam stops of the conference tour were simply titled "Yahoo Developer Tools." Joel insisted that speakers do not rely on slides or rattle through pre-defined presentations, so my "slide deck" for all the talks was the following.

presentation = {
intro:'oh, hai',

Sadly enough, I was busy with other things so I couldn't attend all the worldwide conferences outside my time slot. I especially missed a lot of the Amsterdam leg as I had come down with 'flu and spent the night before trying to become humanly recognisable again and able to deliver an hour's talk. Here are my impressions of what I have encountered though:


The London conference was massive - around 900 developers crammed into the fully sold-out venue in High Street Kensington. For a speaker, the venue was great - lapel mics, big screen, small screens with a countdown - the works. A great plus in the organisation was providing power plugs for everybody in the audience and a very steady wireless. What I found bad was the lack of comfort of the seats in the packed room and the inadequate meal arrangements. One stall for food for 900 people doesn't scale and means people have to wait in line far too long.

Jon Skeet - Humanity epic fail

Of the talks I saw, I was very impressed with Jon Skeet of Google (who is kind of a big deal on Stack Overflow) who brought his horse hand-puppet with him to explain why we are pre-destined to fail as developers when there are so many human confusions to take care of. His big examples were the impossibility of doing simple maths because of coding language bugs and problems writing a calendar app because of date and time formats being generally a jumbled mess.

Stackoverflow Devdays London by  codepo8Stackoverflow Devdays London by  codepo8

Jon's stand-up comedy style of presenting went down really well with the audience (and me) and I'd give him a standing ovation for the best illustration of a leap second I have seen in quite a while. Watch out XKCD.

The leap second by codepo8

There's a bit of camrip-style video of the talk, and Jon has released the notes and slides.

Remy Sharp - jQuery - write less, do more.

The other presentation I followed was Remy Sharp (organiser of the Full Frontal conference) talking about jQuery. Remy's slides are available as a PDF on his blog and it was more or less a deep-dive into what jQuery is about and a detailed explanation of the API. I got the impression that the 45-minute slot in London was a bit too short for this and I think his Cambridge talk was better received, as he had more time to show some cool live demos of the power of jQuery.

The "Yahoo talk"

As with all three presentations, I ad-libbed the 45 minutes, taking the audience through our developer offering, YUI, YQL and Yahoo! open apps (built on the Yahoo! Application Platform) especially.

My main goal was to find a hook into the community, as I found myself looking at 900 people of whom I only knew 10 - London is not a large developer community so normally I am used to speaking to 90% of people I know. The lucky break came when I talked to the maintainers of the Stack Overflow web site (Jeff Atwood of Codinghorror fame). They are big fans of our Geo APIs (which they use to ease sign-up) and wondered if we had a solution for the issue that whilst people are happy to ask good questions on Stack Overflow, they are lazy when it comes to tagging them. The solution is the Yahoo Term Extraction API which I used to whip up a quick Greasemonkey script to automatically analyse the question box on Stack Overflow and populate the tag field:

You can install the script yourself and see the difference. Using this as a hook, I showed a lot of YQL queries in the console, talked about YUI and its ideas, and ended the talk with a preview of Yahoo Open Applications.


The Cambridge location was, as expected, a college within the University (which celebrates its 800th birthday this year). The seats were much more comfortable, wireless worked flawlessly, and the catering was very good. All in all a step up from London, although a step down in attendee numbers. I think about 450 people were there, many of whom took the one hour train from London, as that gig had sold out quickly. I actually met some attendees on the train in the morning and had some insight into what people expected to learn.

Joel Spolsky

Joel is a wonderful presenter - interesting, witty and to the point. In this keynote, he showed a lot of examples of how not to design user interfaces and discussed the dilemma of "Simplicity vs. Power." He showed evidence that adding features to products had always boosted the sales of his own products but to make them work out you need to initially hide them. The general idea is that a great program should feel like it is running effortlessly. This tied in nicely with my presentation, where one of the things I told people about was the Design Pattern library that answers exactly the question of how to build products like these.

Frank Stajano

The other talk I was able to attend was Frank Stajano, a resident lecturer and security expert (and mighty sword-bearer). His talk revolved around application security but instead of doing the classic "prevent yourself from XSS/SQL injection/CSRF" spiel, Frank took a different route. BBC TV in the UK has a program called The Real Hustle which shows how people are scammed by tricksters and gamblers and the psychology behind these successful scams. Despite the abysmal Guy Ritchie style presentation of the show, it is full of great information: Frank and a colleague conducted a detailed research and analysis of all the attacks and the reasons why they work. The paper on the research is available: Seven principles for systems security (PDF). A thoroughly entertaining and fascinating presentation and a great example of how security can be explained without sounding condescending or drowning the audience in jargon. I really hope that there is a recording of the talk.

The Yahoo presentation

Learning from my previous presentation, I cut down on YUI a bit this time and mainly explained why we do YUI the way we do and what it can be used for. I also showed the CSS grids builder which always causes quite a stir - CSS still seems to be a mystery to a lot of people. As the prime example this time I had chosen to extend the auto-tagger for Stack Overflow to work with any web site. You can see it in action in this screencast:

The demo page shows you how to do that in your own documents, all you need to do is embed the script and give it the IDs of the form fields:

<form action="#" method="get" accept-charset="utf-8">
<label for="mainfield">Your Message:</label>
<textarea id="mainfield" name="mainfield">Hello I am a programmer that does care about interfaces. What kind of library can I use that gives me a defined set of widgets that have been tested in the real world?</textarea>
<label for="tags">Tags:</label><input type="text" id="tags" name="tags">
<script type="text/javascript" src="">
<script type="text/javascript">YQLAutoTagger.init('mainfield','tags');</script>

There are some ways to customise the script and its behaviour, all of which are described on GitHub. Download the script from GitHub and read the docs there.

I showed some more YQL goodies like open tables and executing JavaScript inside them and then talked about the Yahoo! Application Platform and Caja. You can listen to a recording of the talk at


The last leg of the Dev Days tour found me wobbly on my legs as the night before I had been hit hard by flu. Nevertheless I managed to drag myself to the location - an old house in a factory complex now used as one of the haunts for smaller events (in the days before we arrived, it had hosted the Affordable Art Fair and a Halloween Party). The venue was cool and cold but people were happy with the arrangements, the AV system was good, the wireless stood up and all was fine. Here's a summary of the talks I caught:

Simon Willison on Python

I don't think there has to be much of an explanation or introduction to Simon. Give that man a command line and a big screen and live coding magic happens. He did a solid job selling Python and Django as a great way to build things, using the Stack Overflow Dev Days web site as his example. He also showed how to parse a CSV file with information concerning endangered animals all over the world, and create a choropleth map from an SVG template indicating the locations of the endangered species. Magic - without rabbits.

Nick Johnson on Google App Engine

Nick did a good job showing how to deploy a new app onto App Engine in under a minute, and explaining how it would scale for you using the magic pixie dust that is inside Google's server architecture. It was an enjoyable talk and made me wonder if I shouldn't move some of my personal apps over. He also asked the audience to shout "Boo" every time he mentioned the word "Cloud," which gave him another brownie point in my book.

The "Yahoo" talk

This time I went really short on YUI, explaining to people the why and where to find information and dived into YQL very early on, as it was the obvious winning feature in all the other locations. My main agenda was to cover as many of the features of YQL in one hour but I soon ran out of time - there is just too much goodness in it. The main example I showed is how to get photos from Flickr and display them. To this end I am using several YQL queries, and use them inside an execute block inside an open table. A detailed write-up of the new flickr.photolist data table is available on my blog. I then continued to explain Caja and the Yahoo Application Platform and that was my talk in Amsterdam. The audio recording of the Amsterdam talk (MP3) is available, too.

In summary

Generally, I had a wonderful time speaking at the Stack Overflow Dev Days and I have to thank the organizers for giving me the opportunity. My job is all about reaching people that are not yet aware of what we do and when I can see hundreds of people flooding Twitter with excited messages about YQL then I am a very happy evangelist and I can see that my job is making a difference. If you took something home to impress your peers and boss with, then I am happy.

I love the concept of having a breadth of subjects and not allowing any of the speakers to just go through slide decks and bring up the same talk over and over again (technically Joel cheated though as he gave the same slide deck every time - boo hiss). I also like it that the conference is backed up by a high traffic communication network and community which means you can easily hear about how you've done. The only thing I would change is do more general talks and less FogCreek talks about their own products. People know of you because of your awesome output, not because you keep telling them at your own conference what you do.

Chris Heilmann (@codepo8)
Yahoo Developer Network