MessagePack in Racket

This is a Racket implementation of MessagePack, a binary data serialisation format. It allows you to serialise (pack) and de-serialise (unpack) Racket object to and from binary data.

Installation

The easiest way to install this library is from the Racket Package Catalog. Run the following code from your shell:

raco pkg install msgpack

If you wish to install the package from this repository use the included makefile:

make install   # Install the package
make remove    # Uninstall the package

Using MessagePack

;;; Import the library first
(require msgpack)

;;; Some object to pack
(define hodgepodge (vector 1 2 (void) '#(3 #t) "foo"))

;;; Packing data
(define packed (call-with-output-bytes (λ (out) (pack hodgepodge out))))
;;; > #"\225\1\2\300\222\3\303\243foo"

;;; Unpacking data
(define unpacked (call-with-input-bytes packed (λ (in) (unpack in))))
;;; > '#(1 2 #<void> #(3 #t) "foo")

The pack function takes a Racket object and a binary output port as arguments and writes the serialised data to the port. The unpack function takes a binary input port and returns one de-serialised object, consuming the necessary amount of bytes from the port in the process. For more details please refer to the documentation.

In the above example code we set the output and input ports to be byte strings so we could work with the packed and unpacked data directly inside the Racket instance.

Status

The library is fully functional, covered by test cases, and the API should be reasonably mature, but I am not yet willing to completely rule out changes. See also below for parts of the library that could not be tested at the moment due to technical reasons.

Caveats

The following cases cannot be tested for the time being:

• The bin32 type, storing a byte string that is 2³² bytes long requires 4GiB, my machine simply runs out of memory.
• The same goes for the str32 type
• The same goes for the array32 type
• The same goes for the map32 type
• The same goes for the ext32 type
• Strings are only tested using ASCII characters, if anyone can generate UTF-8 strings with a given length in bytes please help out.

License

Released under the GPLv3+ license, see the COPYING file for details.