wsgiref — WSGI 实用程序和参考实现

源代码： Lib/wsgiref

The Web Server Gateway Interface (WSGI) is a standard interface between web server software and web applications written in Python. Having a standard interface makes it easy to use an application that supports WSGI with a number of different web servers.

Only authors of web servers and programming frameworks need to know every detail and corner case of the WSGI design. You don’t need to understand every detail of WSGI just to install a WSGI application or to write a web application using an existing framework.

wsgiref is a reference implementation of the WSGI specification that can be used to add WSGI support to a web server or framework. It provides utilities for manipulating WSGI environment variables and response headers, base classes for implementing WSGI servers, a demo HTTP server that serves WSGI applications, types for static type checking, and a validation tool that checks WSGI servers and applications for conformance to the WSGI specification ( PEP 3333 ).

见 wsgi.readthedocs.io for more information about WSGI, and links to tutorials and other resources.

wsgiref.util – WSGI 环境实用程序

This module provides a variety of utility functions for working with WSGI environments. A WSGI environment is a dictionary containing HTTP request variables as described in PEP 3333 . All of the functions taking an environ parameter expect a WSGI-compliant dictionary to be supplied; please see PEP 3333 for a detailed specification and WSGIEnvironment for a type alias that can be used in type annotations.

wsgiref.util. guess_scheme ( environ )

Return a guess for whether wsgi.url_scheme should be “http” or “https”, by checking for a HTTPS environment variable in the environ dictionary. The return value is a string.

This function is useful when creating a gateway that wraps CGI or a CGI-like protocol such as FastCGI. Typically, servers providing such protocols will include a HTTPS variable with a value of “1”, “yes”, or “on” when a request is received via SSL. So, this function returns “https” if such a value is found, and “http” otherwise.

wsgiref.util. request_uri ( environ , include_query = True )

Return the full request URI, optionally including the query string, using the algorithm found in the “URL Reconstruction” section of PEP 3333 。若 include_query is false, the query string is not included in the resulting URI.

wsgiref.util. application_uri ( environ )

类似于 request_uri() , except that the PATH_INFO and QUERY_STRING variables are ignored. The result is the base URI of the application object addressed by the request.

wsgiref.util. shift_path_info ( environ )

Shift a single name from PATH_INFO to SCRIPT_NAME and return the name. The environ dictionary is modified in-place; use a copy if you need to keep the original PATH_INFO or SCRIPT_NAME intact.

If there are no remaining path segments in PATH_INFO , None 被返回。

Typically, this routine is used to process each portion of a request URI path, for example to treat the path as a series of dictionary keys. This routine modifies the passed-in environment to make it suitable for invoking another WSGI application that is located at the target URI. For example, if there is a WSGI application at /foo , and the request URI path is /foo/bar/baz , and the WSGI application at /foo 调用 shift_path_info() , it will receive the string “bar”, and the environment will be updated to be suitable for passing to a WSGI application at /foo/bar . That is, SCRIPT_NAME will change from /foo to /foo/bar ，和 PATH_INFO will change from /bar/baz to /baz .

当 PATH_INFO is just a “/”, this routine returns an empty string and appends a trailing slash to SCRIPT_NAME , even though empty path segments are normally ignored, and SCRIPT_NAME doesn’t normally end in a slash. This is intentional behavior, to ensure that an application can tell the difference between URIs ending in /x from ones ending in /x/ when using this routine to do object traversal.

wsgiref.util. setup_testing_defaults ( environ )

更新 environ with trivial defaults for testing purposes.

This routine adds various parameters required for WSGI, including HTTP_HOST , SERVER_NAME , SERVER_PORT , REQUEST_METHOD , SCRIPT_NAME , PATH_INFO , and all of the PEP 3333 定义 wsgi.* variables. It only supplies default values, and does not replace any existing settings for these variables.

This routine is intended to make it easier for unit tests of WSGI servers and applications to set up dummy environments. It should NOT be used by actual WSGI servers or applications, since the data is fake!

用法范例： 

from wsgiref.util import setup_testing_defaults
from wsgiref.simple_server import make_server
# A relatively simple WSGI application. It's going to print out the
# environment dictionary after being updated by setup_testing_defaults
def simple_app(environ, start_response):
    setup_testing_defaults(environ)
    status = '200 OK'
    headers = [('Content-type', 'text/plain; charset=utf-8')]
    start_response(status, headers)
    ret = [("%s: %s\n" % (key, value)).encode("utf-8")
           for key, value in environ.items()]
    return ret
with make_server('', 8000, simple_app) as httpd:
    print("Serving on port 8000...")
    httpd.serve_forever()