Editing Web Server Gateway Interface (section)

===Example of calling an application===
A full example of a WSGI network server is outside the scope of this article. Below is a sketch of how one would call a WSGI application and retrieve its HTTP status line, response headers, and response body, as Python objects.<ref>{{cite web|url=https://www.youtube.com/watch?v=afnDANxsaYo |archive-url=https://ghostarchive.org/varchive/youtube/20211212/afnDANxsaYo| archive-date=2021-12-12 |url-status=live|title=Creating WSGI Middleware - Alan Christopher Thomas - Minted - PythonKC|date=2015-08-28|publisher=[[YouTube]]|access-date=2017-01-27}}{{cbignore}}</ref> Details of how to construct the <code>environ</code> dict have been omitted.
<syntaxhighlight lang="python3">
from io import BytesIO

def call_application(app, environ):
    status = None
    headers = None
    body = BytesIO()
    
    def start_response(rstatus, rheaders):
        nonlocal status, headers
        status, headers = rstatus, rheaders
        
    app_iter = app(environ, start_response)
    try:
        for data in app_iter:
            assert status is not None and headers is not None, \
                "start_response() was not called"
            body.write(data)
    finally:
        if hasattr(app_iter, 'close'):
            app_iter.close()
    return status, headers, body.getvalue()

environ = {...}  # "environ" dict
status, headers, body = call_application(app, environ)
</syntaxhighlight>