[jerf]

You need a "consistent" stack in the whole of everything executing under "handle_request" if you want that "one single exception handler bracketing the entire request". You don't get that in Javascript; you need a language with more power. There are several viable options: Threading, continuations, some hacked up thing like Python's yield (which is neat, but limited). But something.

Javascript's a very nice, dynamic language in most ways but its functions are very, very weak. They'll get better in the next version of ECMAScript, though. (Node.js will probably benefit from it.)

[tptacek]

I'm pretty sure you're wrong about this. The exact same idiom I used to buffer up requests and feed them whole to a single function that could catch all possible exceptions works just fine in Javascript. Is this an issue with JS exceptions that I'm unaware of? I may just be talking past you.

[jerf]

You're talking about the function of what I posted, I'm talking about the form.

    try:
        something = some_io_that_needs_an_event_callback()
        if do_something_with(something):
            more_io_with_callback()
            some_other_callback_thingy()
        else:
            yet_other_io()
            some_other_io()
    except AnyException:
        do_something_sane()

is not a structure available to you in Node.js, again, pending somebody proving otherwise in Javascript (though I've made this complaint in other places where somebody really should have shown me the code). That expands to tons of code in Javascript, code which is very resistant to abstraction.

Your code block says it is available to you in Ruby. There's no reason why it shouldn't be; it's not a hard compiler transform to manage that. Taking code that looks like a "thread" but compiling it into events and using something-like-continuations to keep the stack together is on the order of a homework problem. Based on what I know about Ruby, the responsibility of those pieces is split up differently but all the pieces must be there. But it's not something Javascript can do (quite yet, and based on what I've seen in Python the 'yield' approach has its own issues).