Definitions of keys and classes

Standard environ keys


The HTTP request method, such as GET or POST. This cannot ever be an empty string, and so is always required.


The initial portion of the request URL’s “path” that corresponds to the application object, so that the application knows its virtual “location”. This may be an empty string, if the application corresponds to the “root” of the server.


The remainder of the request URL’s “path”, designating the virtual “location” of the request’s target within the application. This may be an empty string, if the request URL targets the application root and does not have a trailing slash.


The portion of the request URL that follows the “?”, if any. May be empty or absent.


The contents of any Content-Type fields in the HTTP request. May be empty or absent.


The contents of any Content-Length fields in the HTTP request. May be empty or absent.


When combined with SCRIPT_NAME and PATH_INFO, these variables can be used to complete the URL. Note, however, that HTTP_HOST, if present, should be used in preference to SERVER_NAME for reconstructing the request URL. See the URL Reconstruction section below for more detail. SERVER_NAME and SERVER_PORT can never be empty strings, and so are always required.


The version of the protocol the client used to send the request. Typically this will be something like “HTTP/1.0” or “HTTP/1.1” and may be used by the application to determine how to treat any HTTP request headers. (This variable should probably be called REQUEST_PROTOCOL, since it denotes the protocol used in the request, and is not necessarily the protocol that will be used in the server’s response. However, for compatibility with CGI we have to keep the existing name.)

HTTP_ Variables

Variables corresponding to the client-supplied HTTP request headers (i.e., variables whose names begin with HTTP_). The presence or absence of these variables should correspond with the presence or absence of the appropriate HTTP header in the request.

WSGI environ keys


The tuple (1, 0), representing WSGI version 1.0.


A string representing the “scheme” portion of the URL at which the application is being invoked. Normally, this will have the value “http” or “https”, as appropriate.


An input stream (file-like object) from which the HTTP request body can be read. (The server or gateway may perform reads on-demand as requested by the application, or it may pre- read the client’s request body and buffer it in-memory or on disk, or use any other technique for providing such an input stream, according to its preference.)


An output stream (file-like object) to which error output can be written, for the purpose of recording program or other errors in a standardized and possibly centralized location. This should be a “text mode” stream; i.e., applications should use “n” as a line ending, and assume that it will be converted to the correct line ending by the server/gateway.

For many servers, wsgi.errors will be the server’s main error log. Alternatively, this may be sys.stderr, or a log file of some sort. The server’s documentation should include an explanation of how to configure this or where to find the recorded output. A server or gateway may supply different error streams to different applications, if this is desired.


This value should evaluate true if the application object may be simultaneously invoked by another thread in the same process, and should evaluate false otherwise.


This value should evaluate true if an equivalent application object may be simultaneously invoked by another process, and should evaluate false otherwise.


This value should evaluate true if the server or gateway expects (but does not guarantee!) that the application will only be invoked this one time during the life of its containing process. Normally, this will only be true for a gateway based on CGI (or something similar).