Steve Vinoski's Blog

QCon is always very, very good, but QCon London 2009 last week was the best one yet. Highlights:

• Ola Bini‘s “Emerging Languages in the Enterprise” track on Wednesday had some great talks, especially Rich Hickey’s Clojure talk. Ola’s deep knowledge and love of programming languages made him the perfect host for this track, and he put together a brilliant lineup.
• Speaking of Rich, I consider myself very lucky to have gotten to meet and spend a fair amount of time with him. He’s very bright, talented, knowledgeable, and experienced, and both of his talks were outstanding.
• I introduced Rich to Joe Armstrong at the conference party Wednesday evening and they spent the next few hours talking at length about functional programming, their respective languages, VM implementation issues, concurrency issues, etc. Ola jumped in as well. They also continued the conversation the next day. I just sat back, listened, and learned.
• Getting to spend time again with Joe was excellent. He always has incredibly useful analyses and opinions to express, and in general is fun to be around and easy to learn from.
• I also finally got to meet Ulf Wiger, Erlang developer extraordinaire, in person. He’s a laid back guy, quite well-informed and a deep thinker who can cover a wide variety of topics in amazingly useful detail. His talk on multicore programming in Erlang covered cutting edge Erlang development and presented some very difficult concurrency issues.
• Ulf’s talk, as well as Rich’s second talk, which was on persistent data structures and managed references, were part of Francesco Cesarini‘s “Functional and Concurrent Programming Languages Applied” track on Thursday. I met Francesco, who like Ulf is one of the world’s top Erlang developers, at QCon London last year. He assembled a great track for this conference, with Rich’s and Ulf’s back-to-back talks being way more than enough to sober up any developer who thinks that multicore is not an issue and that today’s methods for dealing with concurrency will continue to work just fine. Best of luck with that!
• Sir Tony Hoare‘s talk about the null reference being his “billion dollar mistake” was great because of all the detail he recounted from some of the early days of computing. He was both informative and entertaining. I was also impressed with Ulf during this talk, whom Professor Sir Hoare invited to come up to the front and present what turned out to be a pretty convincing argument in favor of the null reference.
• Paul Downey‘s talk on the downsides of standardization was by far the most humorous talk I heard, perfect to close out the track, but it also presented a number of hard-won useful lessons about the perils of standardization efforts.

As with all QCon conferences, there were a bunch of interesting tracks running in parallel, and unfortunately I still haven’t figured out how to be in multiple places at once. I had to miss Michael Nygard‘s talk, for example, because my own talk got moved to the same time slot as his.

My talk (PDF) covered the history of RPC, why it got to be the way it was, and why the forces that created it really aren’t all that viable anymore.

The final conference panel was by far the most inventive panel I’ve ever been on. Modeled after the British game show “It’s a Bullseye!” and hosted by none other than Jim Webber, it had contestants from the audience throwing darts to become eligible for a prize. Once a contestant became eligible, Jim would ask the panel — Michael Nygard, Ian Robinson, Martin Fowler, and me — to answer a question submitted by conference attendees either earlier during the conference or live via Twitter. Based on our answers, audience members held up either a green card if they liked the answers or a red one if they didn’t, and if the majority was green, the contestant would win a book. The questions were hard! We had only two minutes each to answer, which for some questions seemed like an eternity but for most was way too short. Anyway, it was great fun, and given how many there were in the audience after three grueling conference days and how much they seemed to be enjoying themselves, it worked very, very well.

If you have any interest at all in leading edge software and computing topics being presented by the world’s most knowledgeable speakers in a fun atmosphere, go to QCon. I guarantee you won’t be disappointed.

I figured the decentralized media types idea that Stefan Tilkov and I each wrote about recently couldn’t be all that simple. So, not surprisingly, it turns out that at least Mark Baker (and according to Mark, also Mark Nottingham (mnot) as well), Bill de hÓra, and James Snell don’t like it. When either Mark or Mark speaks on matters pertaining to the web, I listen; I’ve been around each of them long enough to know that when they aren’t sure whether something is a good idea, it’s definitely worthwhile to take the time to understand why. I don’t believe I’ve ever met Bill or James in person, but I read their blogs for a good reason, plus James just got his blue belt so I’d like to avoid getting on his bad side. :-)

I particularly like Stu Charlton’s opinion on the matter, though, in part because he acknowledges the tension between the needs of the Internet vs. those of intranets.

At the end of the day, I understand the various explanations for why decentralizing media types is not a good idea after all, and I agree with them. I was unaware that mnot had already tried to go down this path. I see this issue as another stop along the way to a more thorough understanding of REST, and bringing it up has gotten some good technical explanations out in the open, where perhaps more people can see them and learn from them. Thanks to those mentioned above for providing those explanations, and to Stefan for kicking off the discussion.

In RESTful systems, media types define the formats of data exchanged between client and server. Standard media types are centrally registered and managed via the Internet Assigned Numbers Authority (IANA). If none of the registered IANA media types fits your application, you’re free to write up and submit a new one that does.

Less than one week ago I was wondering to myself why media types are centrally managed when the web typically prefers decentralization. I was therefore pleasantly surprised today when I read Stefan Tilkov’s posting on this very topic. The proposed solution he describes, from Sanjiva Weerawarana, Paul Fremantle, Jonathan Marsh, and James Clark, is pretty much in line with what I was thinking: register a new media type that has a URI parameter for identifying an actual data description. Very simple and yet potentially extremely effective.

I like this approach for several reasons beyond just the decentralization win. First, this allows us to gain experience with new media types before they’re standardized. Second, this augments rather than replaces the current IANA registration approach, and doesn’t break the existing IANA registration process in any way. Third, it doesn’t break or otherwise negatively impact any existing applications.

So, enough emailing and blogging about it — who’s going to write it and submit it to the IANA? I hereby offer to pitch in and help in whatever way I can.