The Document domain (doc.tcl) maps URLs onto files and directories. It provides more ways to extend the server by registering different document type handlers. This occurs in a two-step process. First, the type of a file is determined by its suffix. The mime.types file contains a map from suffixes to MIME types such as text/html or image/gif. This map is controlled by the Mtype module in mtype.tcl. Second, the server checks for a Tcl procedure with the appropriate name:
The matching procedure, if any, is called to handle the URL request. The procedure should use routines in the Httpd module to return data for the request. If there is no matching Doc_mimetype procedure, then the default document handler uses Httpd_ReturnFile ...