QCon highlights

A QCon presentation style review (mostly)

At QCon this year the influence of Presentation Zen was to be seen everywhere. But I must admit: it didn’t help too much. Sure, the quality of the talks, its content was as great as ever, but I am not sure Garr Reynolds’s influence helped the presentations that much. It mostly felt artificial. The slides may have improved, but they looked so similar, unoriginal. And the presenters were still always craning their necks, standing behind the lectern, or if they dared to stray away, they had to return immediately to push the forward button (please buy a decent presenter, like: this for OS X or this for Windows) One of the exceptions: Sam Newman’s talk on From Dev to Production: Better Living through Build Pipelines and Teamwork, who seemed so at ease with his material, so natural that it was pure delight to watch. I’ve been told that it might be difficult, to get him to stop talking, but in this presentation it came together nicely. Thank you, Sam.

Simon Wardley did a slick presentation presentation as well. His explanation of the cloud “movement” from a historical and economic viewpoint, was spot on. I will especially take with me his view, that it’s not a question ‘if’ you are going to move to the cloud, but ‘when’, because computing power is becoming a commodity, and if you treat it otherwise you will fall back, because you will not be able to innovate on top of it as fast as others are doing.

His presentation on the other hand was completely over the top, with 400+ slides, well rehearsed, but after some time it became tiresome. He simply overdid it, seemed to enjoyed himself so much, that he might as will did it in front of a mirror. Please, cut it down next time.

The slides I probably liked most, were Nat Pryce’s. Simply because they were original: He completely did them by hand on a tablet PC, brushing them up with InkScape. It surely helps that he has a very legible handwriting

He ran a little bit through his different case studies, I think it would have been better to have at most two examples and going a bit deeper into his material on testing asynchronous systems. Still his advice was helpful.

The funniest presentation came from Dan North, I hope they publish the video asap. Without Dan’s presentation, the slides are only half as fun. This in no means says that the slides are only half good, it just means that Dan is a great presenter. You can follow him on Twitter, I think it’s worth it.

And I have to follow his advice to buy me a rubber duck! Yes, a rubber duck: whenever I am furiously hacking on something, losing myself; I then look at my rubber duck and asking it: is this worth it? And the rubber duck just looks back: duh? Ok, it’s not worth it, thank you. Very helpful.

Ralph Johnson on the other hand was rather boring, talking about refactoring; nothing new.

Optimizing CPU cache access in Java

The presentation that absolutely made my head explodes, was “LMAX – How to do over 100K contended complex business transactions per second at less than 1ms latency”. They really pushed performance optimization in Java beyond the limit I had ever considered. They even padded a data structure with additional bytes to ensure that two essential parts (the head and the tail of their own list implementation) were to be placed in two different cache rows of the CPU, to reduce contention. Most of their other optimizations were not so far of, but – for me – unheard of in the Java world.

Facebook create their own PHP compiler & runtime

Where LMAX pushed the Java limits, Facebook created their own PHP compiler to improve the performance of their web site. And they open sourced it (see: HipHopBlog and HipHop), because they had profited in so many ways from open source software that they want to give something back. Great move. But what really resonated with me was their “culture”. They …

1. … create everything in very small teams
2. … still try to rather push some new features out there and fix any (scaleability) problems when they occur

Sure the last principle does not work for everyone, and you have to weigh in the image problems when something really goes wrong, but sometimes we simply are way beyond sanity. Sometimes it feels that an IT department is mostly trying to avoid getting something through the door. Yes, too often those who have to stand up in the middle of the night aren’t those that caused the problems in the first place. But what about taking Sam’s advice and wear the pager yourself for a week after the release. Okay then you have to have access to production systems yourself, and so on yadda, yadda, yadda. Try it. At least ask (“we can’t possibly do that”), and then ask again (“we have never done it”)– and again (“well …”).

Let it REST

Stefan Tilkov is still trying to convince everyone to use REST. Luckily he has lost some of his zeal and even acknowledges that there are some difficulties in adopting the REST mindset. But most of his claims were less provocative then he might have thought. So I could agree with him most of the time. (And I must still thank him, because his zeal provoked me into blogging in the first place, see my very first blog entry.

But I must admit that the best part was “stolen” from Jim Webber (which he explicitly and happily said so himself. Please check out the keynote by Jim and Martin Fowler from QCon 2008): Should an ESB be the base of your SOA? Or which problem does an ESB solve?

If you happen to stumble upon the usual enterprise systems spaghetti landscape:

The idea of an ESB that cleans up the mess might be tempting. Everything now finally looks orderly, everything has its place. Something we like: Order. Cleanliness.

But what happens if you open up the lid?

Oops.

His best argument for REST (from my point of view) is this: When you look at most APIs, they are 90% CRUD, so why use something that might be better for the last 10%? This undermines my strongest argument, that some important services really do not fit the REST style. Yes, they do not fit well, but is that a good argument for the WS-?

Books

As usual I had to buy some books, which I will probably never read (have a look at my library at Library Thing). But, oh, I already finished “Confessions of a Public Speaker” (Scott Berkun, 2010), nice little book, you will probably have finished it, in one or two evenings. Nothing really new, some good stories, even if a little bit rambling along, but good entertainment after a full day of conference sessions.

The other one is “Web Design for Developers” (Brian Hogan, 2010), not yet sure if it was a good choice, but still learned quite a bit on color schemes. Would have preferred less micro-recipes for Photoshop and more about the thought processes, but still a good read up to now.

REST vs. WS-* … Does it help me to achieve my goal?

The discussion about REST vs. SOAP seems to be endless, so — why bother?

Because there seems to be a thorough misunderstanding between the two camps that needs to be resolved. A misunderstanding that pertains to different values hold by each camp. Perhaps “values” is to big a word and viewpoint might be enough, but the discussion evokes so many emotions so much “you just don’t get it” so much ferociousness, “values” seems to be the right notion. (This is my second try to put these thoughts into the right words (I even created my own blog for this), you might want to read that discussion first.)

There are two central issues at play:

1. “The Web” as an entity that can be abused
2. API design

I think the latter is more important and more fundamental, but let me try to get the first out of the way.

The “abused” Web

… or better: the abused HTTP protocol.

Proponents of the REST approach consider using HTTP as a mere transport as abusive (e.g. Tilkov, Vinovsky). For me, using a word like “abuse” sounds like putting HTTP on a throne. You have to worship it. Using it for another purpose as was intended is against the … what? As far as I remember, SMS were initially not intended for use by mere mortals, so sending a message via SMS is an abuse? James Snell puts it right:

“there will always be multiple technologies. We use the technologies that best suit the problem we’re trying to solve. It just so happens that HTTP is well suited to address a hell of a lot of problems.”

If a tool helps me to achieve a goal, I will use it. Perhaps there are better tools or more efficient ways to do things. We can talk about that, but “abuse”?. Do I abuse a hammer when I use its handle to get something out from under the bed?

I hope you can agree with me, but Stefan Tilkov throws in the following analogy:

“would you consider using a RDBMS and then defining a single table only, with two columns, ‘id’ and ‘content’ (the latter a BLOB) an abuse of the RDB”

Yes, it sounds like using a RDB in the wrong way, but if I happen to have a RDB at hand, and the data is unstructured, or simply easier store as a BLOB, so why not? Does it help me to achieve my goal? Sorry, I do not “believe” in “the Web”, the “HTTP protocol” as entities that should be worshiped and defended against the unbelievers.

So if you think that WS-* is an abuse, please let us simply state that we disagree on this point and move on. Can we?

API design

WS is centered around verbs (what you can do with things) and REST is centered around resources (the things itselves). I could stop here, because I think, that’s all there is. But then why is the debate still going on and on and on? Because this is a cultural issue. And as long as you are part of one culture it is very difficult to see value in another culture. Let me try to explain that.

When you have to integrate a bunch of legacy systems that all have some kind of (R)PC-API, it just feels natural to wrap them into WebServices. You do not have to translate all the existing verbs into their RESTful equivalent. In my comment to Stefan, I offered the following existing API as an example:

 (d) scoreCustomerMortgageRisk(customerId)
     // i.e. the customer has send in a mortgage application,
     // that should now be "scored" to decide if we can offer
     // him a credit contract

 (e) promoteToCustomer(personId)
     // a person that is in our system, will now become a
     // customer (an account will be opend, etc.)

 (f) calculateNetInterestRate(credit)

and Daniel Yokomizo translated them into one possible RESTful API:

 (d) PUT /mortage-application/{id}/score

 (e) POST /people/{id}/promotions
     =returning> 303 /customer/{id}

and with (f) he cannot see the “resource”, perhaps because there was no explanation in my comment, but he correctly assumes that this really is nothing but a calculation and he even thinks that RPC might be the right thing (so, not everyone is a zealot in the REST camp).

I think this is the best, most concrete illustration of the different mind sets. For me this looks artificial. Is “mortgage-application” a resource? Is “score” a verb or a resource? I have to translate something that looks natural to me into something unusual. If I had to document the REST services, I still would describe (e) as “Promote to Customer”, because this is the culture I grew up with. But if I had to design an API for resources that are accessible via the Web from scratch, I might try REST, especially if I have (more) people in my team that are experienced in a RESTful style. It still all comes down to my central mantra “Does it help me to achieve my goal?”

Some final remarks and disclaimers

I think XML Schema is a mess and WSDL even more so, but I would like to have a rather formal description of the XML messages I have to send and can receive. Not to generate code, but to improve my code as a consumer of a RESTful web service.

There is a difference, whether you are creating an API that is really used between two parties over the Internet, or if you are (just) connecting systems inside your company using a “platform independent” mechanism. In the latter case I would mostly prefer an RPC style in the previous case I would very thoroughly think about my prospective users (if I want as many users of my services as soon as possible, REST is much simpler to use than WS-*).

I do not question that I can translate each and every verb of my RPC-style API into the four HTTP verbs and some deliberate URL. I know about Turing machines, but I think we all are happy that we do not have to program Turing machines directly. Restricting myself to a set of very strongly defined verbs, might even help, but I fear that eventually the URIs will be very arbitrary. If that is true, nothing will be gained.