1 def simple_app(environ, start_response):
 2     """Simplest possible application object"""
 3     status = ‘200 OK‘
 4     response_headers = [(‘Content-type‘, ‘text/plain‘)]
 5     start_response(status, response_headers)
 6     return [‘Hello world!\n‘]
 7 
 8 
 9 class AppClass:
10     """Produce the same output, but using a class
11 
12     (Note: ‘AppClass‘ is the "application" here, so calling it
13     returns an instance of ‘AppClass‘, which is then the iterable
14     return value of the "application callable" as required by
15     the spec.
16 
17     If we wanted to use *instances* of ‘AppClass‘ as application
18     objects instead, we would have to implement a ‘__call__‘
19     method, which would be invoked to execute the application,
20     and we would need to create an instance for use by the
21     server or gateway.
22     """
23 
24     def __init__(self, environ, start_response):
25         self.environ = environ
26         self.start = start_response
27 
28     def __iter__(self):
29         status = ‘200 OK‘
30         response_headers = [(‘Content-type‘, ‘text/plain‘)]
31         self.start(status, response_headers)
32         yield "Hello world!\n"

 1 import os, sys
 2 
 3 def run_with_cgi(application):
 4 
 5     environ = dict(os.environ.items())
 6     environ[‘wsgi.input‘]        = sys.stdin
 7     environ[‘wsgi.errors‘]       = sys.stderr
 8     environ[‘wsgi.version‘]      = (1, 0)
 9     environ[‘wsgi.multithread‘]  = False
10     environ[‘wsgi.multiprocess‘] = True
11     environ[‘wsgi.run_once‘]     = True
12 
13     if environ.get(‘HTTPS‘, ‘off‘) in (‘on‘, ‘1‘):
14         environ[‘wsgi.url_scheme‘] = ‘https‘
15     else:
16         environ[‘wsgi.url_scheme‘] = ‘http‘
17 
18     headers_set = []
19     headers_sent = []
20 
21     def write(data):
22         if not headers_set:
23              raise AssertionError("write() before start_response()")
24 
25         elif not headers_sent:
26              # Before the first output, send the stored headers
27              status, response_headers = headers_sent[:] = headers_set
28              sys.stdout.write(‘Status: %s\r\n‘ % status)
29              for header in response_headers:
30                  sys.stdout.write(‘%s: %s\r\n‘ % header)
31              sys.stdout.write(‘\r\n‘)
32 
33         sys.stdout.write(data)
34         sys.stdout.flush()
35 
36     def start_response(status, response_headers, exc_info=None):
37         if exc_info:
38             try:
39                 if headers_sent:
40                     # Re-raise original exception if headers sent
41                     raise exc_info[0], exc_info[1], exc_info[2]
42             finally:
43                 exc_info = None     # avoid dangling circular ref
44         elif headers_set:
45             raise AssertionError("Headers already set!")
46 
47         headers_set[:] = [status, response_headers]
48         return write
49 
50     result = application(environ, start_response)
51     try:
52         for data in result:
53             if data:    # don‘t send headers until body appears
54                 write(data)
55         if not headers_sent:
56             write(‘‘)   # send headers now if body was empty
57     finally:
58         if hasattr(result, ‘close‘):
59             result.close()