WSGI

介绍　　

　　WSGI （Web Server Gateway Interface）不是服务器，python模块，框架，API或任何类型的软件。它只是服务器和应用程序通信的接口规范。服务器和应用程序接口端都在PEP 3333中指定。如果将应用程序（或框架或工具包）写入WSGI规范，则它将在写入该规范的任何服务器上运行。

Application Interface

　　The WSGI application interface is implemented as a callable object: a function, a method, a class or an instance with an object.__call__() method. That callable must:

accept two positional parameters:

A dictionary containing CGI like variables; and

a callback function that will be used by the application to send HTTP status code/message and HTTP headers to the server.

return the response body to the server as strings wrapped in an iterable.

 1 #! /usr/bin/env python
 2 
 3 # Python's bundled WSGI server
 4 from wsgiref.simple_server import make_server
 5 
 6 def application (environ, start_response):
 7 
 8     # Sorting and stringifying the environment key, value pairs
 9     response_body = [
10         '%s: %s' % (key, value) for key, value in sorted(environ.items())
11     ]
12     response_body = '
'.join(response_body)
13 
14     status = '200 OK'
15     response_headers = [
16         ('Content-Type', 'text/plain'),
17         ('Content-Length', str(len(response_body)))
18     ]
19     start_response(status, response_headers)
20 
21     return [response_body]
22 
23 # Instantiate the server
24 httpd = make_server (
25     'localhost', # The host name
26     8051, # A port number where to wait for the request
27     application # The application object name, in this case a function
28 )
29 
30 # Wait for a single request, serve it and quit
31 httpd.handle_request()

解析请求 - GET

 1 #!/usr/bin/env python
 2 
 3 from wsgiref.simple_server import make_server
 4 from cgi import parse_qs, escape
 5 
 6 html = """
 7 <html>
 8 <body>
 9    <form method="get" action="">
10         <p>
11            Age: <input type="text" name="age" value="%(age)s">
12         </p>
13         <p>
14             Hobbies:
15             <input
16                 name="hobbies" type="checkbox" value="software"
17                 %(checked-software)s
18             > Software
19             <input
20                 name="hobbies" type="checkbox" value="tunning"
21                 %(checked-tunning)s
22             > Auto Tunning
23         </p>
24         <p>
25             <input type="submit" value="Submit">
26         </p>
27     </form>
28     <p>
29         Age: %(age)s<br>
30         Hobbies: %(hobbies)s
31     </p>
32 </body>
33 </html>
34 """
35 
36 def application (environ, start_response):
37 
38     # Returns a dictionary in which the values are lists
39     d = parse_qs(environ['QUERY_STRING'])
40 
41     # As there can be more than one value for a variable then
42     # a list is provided as a default value.
43     age = d.get('age', [''])[0] # Returns the first age value
44     hobbies = d.get('hobbies', []) # Returns a list of hobbies
45 
46     # Always escape user input to avoid script injection
47     age = escape(age)
48     hobbies = [escape(hobby) for hobby in hobbies]
49 
50     response_body = html % { # Fill the above html template in
51         'checked-software': ('', 'checked')['software' in hobbies],
52         'checked-tunning': ('', 'checked')['tunning' in hobbies],
53         'age': age or 'Empty',
54         'hobbies': ', '.join(hobbies or ['No Hobbies?'])
55     }
56 
57     status = '200 OK'
58 
59     # Now content type is text/html
60     response_headers = [
61         ('Content-Type', 'text/html'),
62         ('Content-Length', str(len(response_body)))
63     ]
64 
65     start_response(status, response_headers)
66     return [response_body]
67 
68 httpd = make_server('localhost', 8051, application)
69 
70 # Now it is serve_forever() in instead of handle_request()
71 httpd.serve_forever()

解析请求 - POST

 1 #!/usr/bin/env python
 2 
 3 from wsgiref.simple_server import make_server
 4 from cgi import parse_qs, escape
 5 
 6 html = """
 7 <html>
 8 <body>
 9    <form method="post" action="">
10         <p>
11            Age: <input type="text" name="age" value="%(age)s">
12         </p>
13         <p>
14             Hobbies:
15             <input
16                 name="hobbies" type="checkbox" value="software"
17                 %(checked-software)s
18             > Software
19             <input
20                 name="hobbies" type="checkbox" value="tunning"
21                 %(checked-tunning)s
22             > Auto Tunning
23         </p>
24         <p>
25             <input type="submit" value="Submit">
26         </p>
27     </form>
28     <p>
29         Age: %(age)s<br>
30         Hobbies: %(hobbies)s
31     </p>
32 </body>
33 </html>
34 """
35 
36 def application(environ, start_response):
37 
38     # the environment variable CONTENT_LENGTH may be empty or missing
39     try:
40         request_body_size = int(environ.get('CONTENT_LENGTH', 0))
41     except (ValueError):
42         request_body_size = 0
43 
44     # When the method is POST the variable will be sent
45     # in the HTTP request body which is passed by the WSGI server
46     # in the file like wsgi.input environment variable.
47     request_body = environ['wsgi.input'].read(request_body_size)
48     d = parse_qs(request_body)
49 
50     age = d.get('age', [''])[0] # Returns the first age value.
51     hobbies = d.get('hobbies', []) # Returns a list of hobbies.
52 
53     # Always escape user input to avoid script injection
54     age = escape(age)
55     hobbies = [escape(hobby) for hobby in hobbies]
56 
57     response_body = html % { # Fill the above html template in
58         'checked-software': ('', 'checked')['software' in hobbies],
59         'checked-tunning': ('', 'checked')['tunning' in hobbies],
60         'age': age or 'Empty',
61         'hobbies': ', '.join(hobbies or ['No Hobbies?'])
62     }
63 
64     status = '200 OK'
65 
66     response_headers = [
67         ('Content-Type', 'text/html'),
68         ('Content-Length', str(len(response_body)))
69     ]
70 
71     start_response(status, response_headers)
72     return [response_body]
73 
74 httpd = make_server('localhost', 8051, application)
75 httpd.serve_forever()