:- use_module(library(http/http_dispatch)). [det]http_reply_file(+FileSpec, 
+Options, +Request)
[det]http_reply_file(+FileSpec, 
+Options, +Request)true (default), handle If-modified-since and send 
modification time.true (default false) and, in addition to 
the plain file, there is a .gz file that is not older than 
the plain file and the client accepts gzip encoding, send 
the compressed file with Transfer-encoding: gzip.true (default false) the system maintains 
cached gzipped files in a directory accessible using the file search 
path http_gzip_cache and serves these similar to the static_gzip(true) 
option. If the gzip file does not exist or is older than the input the 
file is recreated.false (default), validate that FileSpec does 
not contain references to parent directories. E.g., specifications such 
as www('../../etc/passwd') are not allowed.
If caching is not disabled, it processes the request headers
If-modified-since and Range.
http_reply(not_modified) http_reply(file(MimeType, Path))