WSGIcompliant

WSGIcompliant refers to software that adheres to the Web Server Gateway Interface (WSGI), the standard interface between Python web applications and web servers. The term is commonly written as "WSGI-compliant" or "WSGIcompliant." The goal of WSGI is to promote portability and interoperability across servers, frameworks, and middleware in the Python ecosystem.

Core contract is defined by a callable interface. A WSGI-compliant application is a callable with the signature application(environ, start_response). The environ argument is a dictionary containing request data such as the method, path, query string, and server information. The start_response argument is a callable that the application uses to begin the HTTP response by supplying a status string (for example, "200 OK") and a list of header tuples. The application returns an iterable yielding byte strings, which form the response body. The server invokes the application for each request and iterates over the response iterable.

WSGI specifications evolved to cover Python 3 with PEP 3333, building on the original PEP 333. The standard is widely supported by servers such as Gunicorn, uWSGI, mod_wsgi, and Waitress, and by major frameworks like Django, Flask, and Pyramid. Middleware can wrap applications to modify the environ or headers while preserving the WSGI contract.

Key compliance details include: ensuring required environ keys (such as REQUEST_METHOD, PATH_INFO, QUERY_STRING, SERVER_NAME, SERVER_PORT) are present; returning a valid status string and header list via start_response; yielding bytes from the response iterable; and maintaining proper resource handling and separation of concerns between server, application, and middleware. WSGI-compliant components enable running the same app across multiple servers and configurations, fostering a flexible and extensible web stack.