figure possible browser display where the background text is just an ordinary html document and the pop-up window is dynamically generated by the popupdata py script the rest of this describes built-in modules related to the low-level interface by which python interfaces with webservers and frameworks topics include cgi scriptinga technique used to access python from third-party web servers and wsgia middleware layer used for writing components that integrate with python' various web frameworks cgi the cgi module is used to implement cgi scriptswhich are programs typically executed by webserver when it wants to process user input from form or generate dynamic content of some kind when request corresponding to cgi script is submittedthe webserver executes the cgi program as subprocess cgi programs receive input from two sourcessys stdin and environment variables set by the server the following list details common environment variables set by webserversvariable description auth_type content_length content_type document_root gateway_interface http_accept http_cookie http_from http_referer http_user_agent path_info path_translated query_string remote_addr remote_host authentication method length of data passed in sys stdin type of query data document root directory cgi revision string mime types accepted by the client netscape persistent cookie value email address of client (often disabledreferring url client browser extra path information passed translated version of path_info query string remote ip address of the client remote host name of the client lib fl ff