Made the handler a bit more robust. And added some comments in the code.

config.py

@@ -9,7 +9,7 @@
     chroot = "./",
     pid_file = "/run/mongrel2-wsgi.pid",
     default_host = HOST,
-    port = 6767
+    port = 80
     )
 
 handler_wsgi = Handler(send_spec = 'tcp://127.0.0.1:9997',

run/mongrel2-wsgi.pid

@@ -1 +1 @@
-953
+1184

test_wsgi_app.py

@@ -61,7 +61,7 @@ def application(environ, start_response):
     """ The WSGI test application """
     # emit status / headers
     status = "200 OK"
-    headers = [('Content-Type', 'text/html'), ]
+    headers = [('Content-Type', 'text/html;charset=utf-8'), ]
     start_response(status, headers)
 
     # assemble and return content
@@ -71,7 +71,7 @@ def application(environ, start_response):
         'abs_path': os.path.abspath('.'),
         'filename': __file__,
         'python_path': repr(sys.path),
-        'wsgi_env': '\n'.join([row_template % item for item in environ.items()]),
+        'wsgi_env': '\n'.join([row_template % item for item in sorted(environ.items())]),
     }
     return [content.encode('utf-8')]
 

wsgi-handler.py

@@ -2,6 +2,7 @@
 # -*- coding: utf-8 -*-
 
 import os, sys
+from uuid import uuid4
 
 from mongrel2 import handler
 import json
@@ -12,12 +13,14 @@
 except:
     import StringIO
 
-DEBUG = True
+DEBUG = False
 
-sender_id = "BA73C5F4-5ADA-4946-8980-1D255EB9A765"
-
-conn = handler.Connection(sender_id, "tcp://127.0.0.1:9997",
-                          "tcp://127.0.0.1:9996")
+# setup connection handler
+# sender_id is automatically generated 
+# so that each handler instance is uniquely identified
+conn = handler.Connection(str(uuid4()), 
+        "tcp://127.0.0.1:9997",
+        "tcp://127.0.0.1:9996")
 
 def simple_app(environ, start_response):
     """Simplest possible WSGI application object"""
@@ -31,7 +34,7 @@ def encode_response(data, encoding='utf-8'):
     return [d.encode(encoding) for d in data]
 
 def simple_app_utf8(environ, start_response):
-    """Simplest possible WSGI application object"""
+    """Simplest possible WSGI application object with UTF-8"""
     status = '200 OK'
     response_headers = [('Content-type','text/plain; charset=utf-8')]
     start_response(status, response_headers)
@@ -44,50 +47,60 @@ def wsgi_server(application):
     Any encoding must be handled by the WSGI application itself.
     '''
 
+    # TODO - this wsgi handler executes the application and renders a page 
+    # in memory completely before returning it as a response to the client. 
+    # Thus, it does not "stream" the result back to the client. It should be 
+    # possible though. The SimpleHandler accepts file-like stream objects. So, 
+    # it should be just a matter of connecting 0MQ requests/response streams to 
+    # the SimpleHandler requests and response streams. However, the Python API 
+    # for Mongrel2 doesn't seem to support file-like stream objects for requests 
+    # and responses. Unless I have missed something.
+
     while True:
         if DEBUG: print "WAITING FOR REQUEST"
 
+        # receive a request
         req = conn.recv()
-
         if DEBUG: print "REQUEST BODY: %r\n" % req.body
 
         if req.is_disconnect():
             if DEBUG: print "DISCONNECT"
             continue #effectively ignore the disconnect from the client
 
+        # Set a couple of environment attributes a.k.a. header attributes 
+        # that are a must according to PEP 333
         environ = req.headers
-        # Set a couple of environment attributes that are a must according to PEP 333
-        environ['SERVER_PROTOCOL'] = u'HTTP/1.1' # SimpleHandler expects a server_protocol
+        environ['SERVER_PROTOCOL'] = 'HTTP/1.1' # SimpleHandler expects a server_protocol, lets assume it is HTTP 1.1
         environ['REQUEST_METHOD'] = environ['METHOD']
         if ':' in environ['Host']:
             environ['SERVER_NAME'] = environ['Host'].split(':')[0]
             environ['SERVER_PORT'] = environ['Host'].split(':')[1]
         else:
             environ['SERVER_NAME'] = environ['Host']
-            environ['SERVER_PORT'] = '80'
+            environ['SERVER_PORT'] = ''
         environ['SCRIPT_NAME'] = '' # empty for now
         environ['PATH_INFO'] = environ['PATH']
         if '?' in environ['URI']:
             environ['QUERY_STRING'] = environ['URI'].split('?')[1]
         else:
             environ['QUERY_STRING'] = ''
-        try:
+        if environ.has_key('Content-Length'):
             environ['CONTENT_LENGTH'] = environ['Content-Length'] # necessary for POST to work with Django
-        except:
-            pass
         environ['wsgi.input'] = req.body
 
         if DEBUG: print "ENVIRON: %r\n" % environ
 
-        # SimpleHandler needs file-like stream objects
+        # SimpleHandler needs file-like stream objects for
+        # requests, errors and reponses
         reqIO = StringIO.StringIO(req.body)
         errIO = StringIO.StringIO()
         respIO = StringIO.StringIO()
 
+        # execute the application
         handler = SimpleHandler(reqIO, respIO, errIO, environ, multithread = False, multiprocess = False)
         handler.run(application)
 
-        # Get response and filter out the response (=data) itself,
+        # Get the response and filter out the response (=data) itself,
         # the response headers, 
         # the response status code and the response status description
         response = respIO.getvalue()
@@ -101,12 +114,13 @@ def wsgi_server(application):
         # Especially the WSGI handler from Django seems to generate them (2 actually, huh?)
         # a BOM isn't really necessary and cause HTML parsing errors in Chrome and Safari
         # See also: http://www.xs4all.nl/~mechiel/projects/bomstrip/
-        # Although I still find this a ugly hack.
+        # Although I still find this a ugly hack, it does work.
         data = data.replace('\xef\xbb\xbf', '')
 
         # Get the generated errors
         errors = errIO.getvalue()
 
+        # return the response
         if DEBUG: print "RESPONSE: %r\n" % response
         if errors:
             if DEBUG: print "ERRORS: %r" % errors