Convention over configuration is subclassing?

Having now played a little bit with Ruby on Rails, I am starting to wonder wether the much touted "convention over configuration" is really just a different implementation of subclassing. That is certainly what it felt like, and the Wikipedia article referenced states that "a developer only needs to specify unconventional aspects of the application."

Or perhaps slightly more accurately, both subclassing and convention over configuration would appear to be a form of programming by difference or "refinement".

Ruby (and Rails) scalability?

Recently I wrote about Node.jsperformance, comparing it to my (still non-public, sorry!) Objective-C based libµhttp wrapper and Apache on my main development machine of the time, a MacBook Pro.

Node.js did really well on tasks that have lots of concurrent requests that are mostly waiting, did OK on basic static serving tasks and not so well on compute-intensive tasks.

Having developed an interest in minimal web-servers, I wondered how Sinatra and, by association, Ruby on Rails would do.

For Sinatra I used the scanty blog engine and the basic "Hello World" example:

---

require 'sinatra'

get '/hi' do
  "Hello World!"
end

---

For Ruby on Rails, I used the blog tutorial "out of the box", invoking it with "rails s" to start the server. In addition I also had RoR just serving a static file instead of the database-backed blog. All this on my new dev machine, a 2011 MacBook Air with 1.8 GHz Intel Core i7 and 4 GB of DRAM. I also discovered that httperf is a much better benchmark program for my needs than ab. I used it with 100 requests per connection, a burst length of 100 and a sufficient number of connections to get stable results without taking all day.

Platform	# requests/sec
Apache	5884
Sinatra Hello World	357
Ruby on Rails static page	312
Sinatra scanty blog	101
Ruby on Rails blog	17

This seems really slow, even when doing virtually nothing, and absolutely abysmal when using the typical RoR setup, serving records from an SQL database via templates. I distinctly remember my G5 serving in the thousands of requests/s using WebObjects 6-7 years ago.

Is this considered normal or am I doing something wrong?

The surprising thing about Objective-C...

Alex Payne, when asked "Are you surprised at the popularity of any current languages?" during the preview of emerging languages for OSCON 2011'semerging languages track:

Alex Payne: I'm constantly surprised at the popularity and success of Objective-C. Almost everyone I know tells the same story about Objective-C: they started learning it and they hated it. They thought it was the worst of C and the worst of dynamic languages. And then eventually, they learned to love it. Most of the time, that software works pretty darn well, so who am I to judge? I'm pleasantly surprised by the continued success of Objective-C, and I think it should be taken as a lesson for the language designers out there.

This is echoed by the the first (and as of this writing only) comment to the post:

Alasdair Allan [18 July 2011 10:09 AM] I certainly agree with Alex about Objective-C, when I was initially learning the language I deeply despised it. Now I love it, and think it's one of the more elegant and powerful of the (many) languages I know. Definitely a lesson to language designers, do what you think is right and ignore the crowds. If you are right people will grow to love your language, just as soon as they figure it out.

I actually liked Objective-C pretty much from the start, but then again at that time (1986) there simply wasn't anything close that I had access to, and writing an Objective-C pre-processor and runtime on my Amiga was simply more feasible than a C++ frontend or a complete Smalltalk VM.

Modifying the sentiment expressed slightly, I'd say that from a theoretical point of view, I hate Objective-C and think it's a bad joke, a trainwreck. However, from practical experience, I love it and find it's one of the most productive languages out there for actually building stuff. And no, it's not just about the frameworks, as I've used Objective-C in non-NeXT, non-Apple environments where we had to build most of our own frameworks.

So while I support Alasdair's comment, my lesson for language designers is that our theory appears to not be particularly good at predicting reality. In other words: our theory sucks has many research opportunities.

Lazy Initialization

Traviscautions against lazy initialization. Spooky coincidence: I just managed to fix an extremely mysterious memory smasher in an Objective-C program's exception handling code by moving the lazily initialized localization code to app startup. Not sure wether localizing exceptions is really such a good idea in the first place, but having the localization code run inside the exception handling code does seem pushing it a bit.

So couldn't agree more.

Speed matters

Greg Linden recounts Marissa Mayer's talk at Web 2.0 showing how even very small decreases in performance have highly measurable impacts on users, and for web businesses on the bottom line.

The change was an increase from 10 to 30 search results, which was expected to produce an increase in user satisfaction, because users had asked for more search results. Instead, there was a completely unexpected and at first inexplicable 20% drop in traffic after the change was implemented. Only after some time did the team discover that the new results page took half a second longer to display, and in further testing they found that every 100 ms delay caused a measurable drop in clicks.

While I am not aware of similar research on desktop apps, I am sure that the same principle applies: speed matters, a lot; and it matters pre-consciously, that is, long before users will mention speed as an issue.

The experienced craftsman plans less

Christopher Alexander via 37 signals:

The essence of this process is very fundamental indeed. We may understand it best by comparing the work of a fifty-year-old carpenter with the work of a novice. The experienced carpenter keeps going. He doesn’t have to keep stopping, because every action he performs, is calculated in such a way that some later action can put it right to the extent that it is imperfect now. What is critical here, is the sequence of events. The carpenter never takes a step which he cannot correct later; so he can keep working, confidently, steadily.

The novice by comparison, spends a great deal of his time trying to figure out what to do. He does this essentially because he knows that an action he takes now may cause unretractable problems a little further down the line; and if he is not careful, he will find himself with a joint that requires the shortening of some crucial member – at a stage when it is too late to shorten that member. The fear of these kinds of mistakes forces him to spend hours trying to figure ahead: and it forces him to work as far as possible to exact drawings because they will guarantee that he avoids these kinds of mistakes.

The difference between the novice and the master is simply that the novice has not learnt, yet, how to do things in such a way that he can afford to make small mistakes. The master knows that the sequence of his actions will always allow him to cover his mistakes a little further down the line. It is this simple but essential knowledge which gives the work of a master carpenter its wonderful, smooth, relaxed, and almost unconcerned simplicity.

Mac App Store won't let me buy apps: solution

Just tried to buy an app via the Mac App Store and it was absolutely refusing to take my money. Various suggestions I've seen on the web such as clearing caches,resetting them via iTunes advanced preferences, rebooting, retrying, using slight variations of my account name all made no difference whatsoever.

The solution turned out to be manually signing in using the Store menu (manually sign out if you are already signed in). At that point I was allowed to update/verify my billing information and subsequent purchase attempts worked.

In previous attempts, I had not signed in manually, but rather had the App Store do the sign-in after I attempted to purchase.

So needs a little more work...