How would you compare a Scala-based web server with other web frameworks?

Question

I have read about Scala but have not been able to do comparative analysis of other web programming frameworks on the basis of:

• maintainability (does the Scala language facilitate the maintainability of such a web framework, compared to, say, a Php-based one?),
• scalability (what OS is best adapted for a Scala wab server to be scalable?),
• compatibility (Like Php works well with Apache web server and asp.net with IIS., Scala must have some specific web server compatibility),
• and other rational categories.

Answer 1

An web application framework like Lift sums it up nicely:

And because Lift applications are written in Scala, an elegant new JVM language, you can still use your favorite Java libraries and deploy to your favorite Servlet Container. Use the code you've already written and deploy to the container you've already configured!

So you can use any Servlet 2.4 engine (e.g., Tomcat 5.5.xx, Jetty 6.0, etc.) you want.
The advantage of Scala itself compared to other language is not as important as the advantage that a web framework (like Lift or other Scala-based web frameworks) can offer over other web framework applications (Rails, Django, ...)

Answer 2

EDIT

The question is better worded now, though still too open for my taste. Still, I'm leaving my original answer as a reference.

Original Answer

This question is rather vague, and the non-vague part is duplicated. See "How many Scala web frameworks are there?"