June 4, 2003 spout

My First API Review

Wed, June 4, 2003

Maybe you’re getting tired of my posting my firsts” at MS, but that’s the beauty of this medium. I get to say what I feel like and you get to listen or not, as you choose. Mostly this Dear Diary” format helps me to digest the world around me. Many times, the writing itself has helped me to clear my head. If you haven’t tried it yourself, I recommend it.

So, on with my next first.” Today I crashed an API review. I happen to be on a few internal Longhorn mailing lists and recently got an announcement of a new API that was going up for its first review. I didn’t know what to expect, but I hoped at least to see some familiar faces and to introduce myself around.

Now, the way I work things, I try to really pack myself into meetings when I’m up in Redmond so that I can get the most out of my time away from home (I’m still based in Portland, OR). In this case, I had a meeting scheduled from 9am to 10am in building 5 and then had to truck across campus to building 42 for the API review at 10am. Needless to say, I was late (the only thing harder than finding parking in the sea of cars after 9am is finding your anonymous rental car when you come back for it). Luckily, MS meetings seem to start late as a matter of course, so I hadn’t missed anything. However, I was a bit surprised that in more than a month of introducing myself around, there was a room full of 10+ people and no familiar faces. They glanced up at me when I came in the door and seemed a bit confused as to who I was, but didn’t ask or toss me out on my butt (it’s handy being 6′5″ sometimes : ).

The process was pretty cool. Apparently the team building the API had answered a standard questionnaire from the review team, which included target users, potential security problems and representative sample code that users would be expected to construct. The review team had prepared by going over the questionnaire and prepared topics of discussion (the latter making this review process better than most I’d attended). The API team provided answers to the questions and took notes on how to fix their API.

I was impressed with the whole thing. The API team was very open to suggestions for improvement, even letting me put in my two cents (I couldn’t help myself : ). And the design team gave out just the kind of advice I want all .NET APIs to follow, e.g. use best practice coding conventions in sample code, support IDisposable at a macro level instead of a micro level, expose collections from properties returning IEnumerable (not from the parent object itself), prefer properties over Get/Set methods (as appropriate), don’t tack the name of the enumeration type onto the enumeration values themselves, prefer overloads to parameters that can be null, prefer typed parameters to object parameters, etc. In addition, where the API team had reinvented the wheel (they were experts in their problem domain, not the entire .NET Framework Class Library, after all), the review team pointed them at what to emulate and where to look for more guidance. The whole process gave me quite a bit of confidence in .NET maintaining the high degree of consistency that’s it’s achieved to date (the FCL consistency is not perfect, I admit, but it’s a damn sight better than COM APIs ever were and don’t even get me started on Win32).

After all that, I did finally get to introduce myself (the note taker on the API team wanted to know who was complaining : ), I helped name a Longhorn data structure and I met a General PM that I needed to talk to anyway, so it was a useful experience all around.