> Am I right, that it uses its own protocol, i.e. no WAI?

To answer your question: yes, Salvia uses its own protocol. Athough the term `protocol' might mean different things when looked at from different perspectives.

How do I put this delicately? I do not think WAI is the way to go.

On the Hackage page of WAI I read: "Provides a common protocol for communication between web aplications and web servers." This means that WAI is a proposed standardized interface intended to sit between server and a web application. There several reasons why I don't like the idea of a standardized interface between the application server and the web application.

First of all, no one will ever agree on this type of interface. Not on the level of abstraction, not on the actual naming of the datatypes, not on the amount of documentation, not on the placement of the parenthesis. I, for example, don't like WAI at all: I do not want be forced to use enumerators for the output, ByteStrings for the input, only 10 predefined response codes, etc.

[..] 

What I do like to see though, is something like the Ruby Rack interface, which calls itself a "a Ruby Webserver Interface". This is an interface between the actual OS/network and the application server, not an interface between an application server and the web application. Call it WSI not WAI, this subtle difference actually means a lot.

This WSI would just give me file handle/socket and possible a pre-parsed HTTP message, but that is all. A Rack-like interface would allow me to run my Salvia web applications on any backend, like CGI, or in mod_haskell, in the blazingly fast iteratee based Hyena or behind an Apache proxy. But still, the web application is written against Salvia (or the framework you like most) and can piggy bag on all the neat features it supplies.

Salvia itself has such a WSI, although I'm pretty sure this one is to abstract and high level to be a true candidate for any form of standardization.