I had the opportunity to speak on a panel at DCWeek 2012 this past week: “Five Crucial APIs to Know About”. (I am not listed on the speakers page, as I was a rather last-minute addition.) Conversation ranged from what goes into making a good API – dogfooding, documentation, focus – to pitfalls to be aware of when building your business on an external API. It was a fun and informative discussion, and I walked away with plenty to chew on.
An API is all about two things: Abstraction and Interaction. It takes something messy, abstracts away some of the details, and then you, as a programmer, interact with that abstraction. That interaction causes the underlying code to do something (and hopefully making your life easier). If you interact with it differently, you’ll get different results. Understanding an API, then, requires understanding both the abstraction as well as how you are meant to interact with it.
Now, DCWeek focuses primarily on the startup scene. As such, I expected that most of my fellow panelists would be focusing on web-exposed APIs. Sure enough, there was plenty of talk on Facebook, Twilio, Twitter, and laundry list of other HTTP-accessible APIs. All of which are great! Note, though, that these APIs share one common thing: They are all network-reliant APIs. As such, they are built on a whole bunch of other APIs, but at the end of the day, they all route through one specific API (or a clone): Berkley Sockets.
Why should you care about a 30-year-old API when you care about tweets and friends and phone calls? Stop for a moment and think about what those high-level APIs are built on: a network. Worse – the Internet. A series of tubes. Leaky, lossy, variable-bandwidth tubes. And it’s only getting worse – sometimes you’re on a high-bandwidth wifi connection; other times you’re on a crappy, intermittent cellular connection in a subway tunnel.
The user’s experience with a high-level network API is going to be directly impacted by socket options chosen several layers down – often just by default – but different experiences require different expectations from the network. Do you have a low-latency API that provides immediate user-interactive feedback in super-short bursts? Then you might want to learn about Nagel’s Algorithm and TCP_NODELAY. Does your app require a user to sit and stare at a throbber while you make a network call? You might want to consider adjusting your connection, send, and receive timeouts to provide more prompt feedback when the network fails.
And believe me: the network will fail. But how do you handle it? As programmers, we tend to focus on the so-called “happy path”, relegating failure handling to second-class status. Unfortunately, treating failure as unlikely is simply not acceptable in a world of ubiquitous networking and web services. Not all network failures are the same, and providing the best user experience requires understanding the difference between the various types of failures in the specific context of what you were attempting to accomplish.
So take a moment and do some research. If you’re using a networked API that exposes network details, learn about them and tweak them for the specific task at hand. If you’re writing an API, consider how users will be accessing it, and provide them guidance with how to achieve the best possible experience over the network. The people using your apps will thank you.
I’d like to thank my fellow panelists – Greg Cypes, Sasha Laundy, and Evgeny Popov – for such an interesting discussion, as well as to thank our moderator Matt Hunckler for keeping us on track. I hope we can do it again in the future.