This is a good question, and the answer is philosophical purity and pragmatism. Philosophically, some people believe that this information should be encapsulated in the HTTP response body, while others believe that they should be able to leverage all of the parts of the HTTP spec including the response headers. Pragmatically, certain environments make it harder or easier to access certain parts of request and response objects, but the lowest common denominator is the body content.
But take a look at the Finagle example from Heroku and compare it to the example from vert.x. There's a lot of boilerplate in the Finagle version because Finagle is a general purpose async service framework, which was my entire point.
Hmmm... I applied at Twitter and got the coding problem done right. I also contributed to one of Twitter's open source projects, "Snowflake." Either you got to have a great story like this Iowa guy, or hiring at Twitter is broken. :-( This might be my next HN post: "How I Interviewed Great at Twitter but a bad coder got my job."
Twitter (https://twitter.com) is a real-time information network with the mission of connecting people everywhere to the latest information that is interesting and relevant to them. We're hiring across the organization, for a broad range of technical and non-technical positions. Come help us solve some hard problems!
I applied to Twitter and the HR person asked me for dates for phone interviews, and then didn't respond for weeks after I gave them the dates. Twitter HR and their recruitment process is amongst the worst I've ever encountered.
Also, if you get rejected by them, they don't have the common courtesy to let you know, even if you try contacting them. Apparently it's beneath them to respond with even 140 characters.
I went through several rounds of interviews that seemed to go well, and was asked "when i coukd start" - i had to follow up with the internal recruiter several times before I got the "we've decided to take this position in a different direction" rejection.
I found something far better though, thankfully. My impression from the interview process was internal chaos, among other things.
I applied for an internship and got two interviews, but they seemed pretty disorganized. They often called at different times from what they said they would (usually when I was in class). They also had to reschedule the interviews several times. The initial informational phone call I also got twice which was strange (about half way through the second one I mentioned she had called the day before with the same information). Seems like a fun place to work though and the interviewers were great.