Un des piliers du Web est le protocole de communication sur lequel il repose, HTTP.
Tornado comes with limited support for WSGI. However, since WSGI does not support non-blocking requests, you cannot use any of the asynchronous/non-blocking features of Tornado in your application if you choose to use WSGI instead of Tornado's HTTP server. Some of the features that are not available in WSGI applications: @tornado.web.asynchronous, the httpclient module, and the auth module.
in other words: WSGI sucks
I’ve recently been working on an implementation of cookie-based authentication for CouchDB. This is important for pure CouchDB applications (couchapps), where browsers communicate directly with CouchDB. Currently browsers can be authenticated using HTTP basic auth but the popup login box can be disruptive and confusing for users.
don't miss the picture.