[prospero]

First, the analysis relies on every step from request to response being evented, which in turn relies on the existence of event-based libraries for everything you want to do.

Also, most languages don't have a good way of dealing with callbacks. They tend to make the code verbose and difficult to reason about. This is especially true for non-trivial applications, where there are more than two or three callbacks chained together.

However, you can counter-argue that the additional complexity isn't endemic to the programming model, only certain languages. Also, in languages which support multiple threads (read: not Javascript), a hybrid approach that uses events where possible, and threads where necessary, may retain many of the benefits of the event-based approach.

[andrewvc]

First, the analysis relies on every step from request to response being evented, which in turn relies on the existence of event-based libraries for everything you want to do.

This is one of the main reasons I like node.js, EVERYTHING is evented, if it isn't it's probably a bug, or at least carefully explained why it can't be (and usually there's an async alternative).

[IgorPartola]

IIRC it does not support things like the mysql lib because it is normally not event driven. So yes everything in node.js is event driven, but not everything you may need is included. Last I checked work was being done on it. The solution was to create a thread pool and treat communicating with it as an event driven protocol.