The Mote Messaging Language or Mote"XML" format is a subject-object-value data encoding format for which the human-readable representation is commonly presented using XML and a toolset exists for easily shifting between the XML and binary representations.
This document gives an overview of protocol version 1 only!
The format encodes each element using a control byte and subsequent subject, type, value and buffer bytes. The control byte establishes the presence and length of the other fields. Version 1 of the protocol supports only signed integers with up to 4 bytes of length.
BSTTTVVV S8 T8 T8 T8 T8 V8 V8 V8 V8 BL BB .. BB
## .. ## - 1-255 buffer bytes
##----------- optional buffer length byte
## ## ## ##- 0, 1, 2 or 4 value bytes
## ## ## ## ------------ 1, 2 or 4 type bytes
## ------------------------ subject byte
+++ value (0,1,2,4 bytes)
+++--- type (1,2,4 bytes)
+------ subject
+------- buffer present
Using the format assumes a common set of meanings for the object values. A set of agreed object types is available in the dt_types.txt file in a (separate repository)[https://github.com/proactivity-lab/dt-types]. The XML tools use the dt_types.txt for input, while the header file defines all the type names as enums and can be used from C code.
Message composition is performed using an encoder. The encoder is intitalized with MLE_initialize and requires a buffer to work on. The encoder is passed to any subsequent encode commands and the buffer is finalized with MLE_finalize. Occurrance of errors is possible with MLE_errors.
The encoder fundamentally works with an ml_object_t object, but convenience functions exist to pass different sets of values directly.
The decoder functions work directly on a buffer and search for matching objects.
The iterator functions use an interator context and are therefore more efficient than normal decoder functions - they do not have to start from the first byte each time.
On a Linux system the encoder/decoder functions can be used by linking against the libmlformat library. The library is also a dependance for the Python tools described in the Tools chapter. The library can be built with make in the lib directory.
Python-based transformation tools that use the library are available from (python-motexml)[https://github.com/proactivity-lab/python-motexml]. This includes command-line tools for encoding/decoding whole messages and a wrapper for use in python applications.
For embedded applications it is recommended to use the enums from dt_types.h header and simply include the mld.c, mle.c, mli.c and mlo.c files for compilation.
A Debian package of the library can be made with build-deb.sh, it uses checkinstall to package the library.