As current maintainer of Sinatra, Konstantin is an Open Source developer by heart. Ruby has become his language of choice since 2005. He regularly contributes to different widespread projects, like Rubinius, Rack, Travis, Rails and MRI. He currently holds the position of "Berry Sparkling Lord" at Travis CI.
We don't know HTTP
Everyone knows HTTP! Well, that's not entirely true. There are large parts unknown to most web developers, well, even browser vendors, as it seems, and the wheel is invented over and over again to fix issues we wouldn't even have, if people would make use of their toolbox. There are two options to fix this: You can reading RFC 2616 over and over again or you can listen to this highly opinionated talk exploring facets of HTTP that most developers are probably not too well aware of and how to make best use of it.