The
HTTP protocol provides for transfer encodings. These define
filters applied to the data described by the Content-type.
The two most popular transfer encodings are chunked and
deflate. The chunked encoding avoids the need
for a Content-length header, sending the data in chunks,
each of which is preceded by a length. The deflate encoding
provides compression.
Transfer-encodings are supported by filters defined as foreign
libraries that realise an encoding/decoding stream on top of another
stream. Currently there are two such libraries: library(http/http_chunked.pl)
and library(zlib.pl).
There is an emerging hook interface dealing with transfer encodings.
The
library(http/http_chunked.pl) provides a hook used by
library(http/http_open.pl) to support chunked encoding in http_open/3.
Note that both http_open.pl and http_chunked.pl
must be loaded for http_open/3
to support chunked encoding.
- http_chunked_open(+RawStream,
-DataStream, +Options)
- Create a stream to realise HTTP chunked encoding or decoding. The
technique is similar to library(zlib), using a Prolog stream as a filter
on another stream. See online documentation at
http://www.swi-prolog.org/
for details.
