cbExiGen is a code generator which creates the codec library cbV2G for encoding and decoding messages using the Vehicle To Grid Transport Protocol (V2GTP). It is capable of processing XML schemas as defined in the standards DIN 70121, ISO 15118-2 and ISO 15118-20, and derivates of these. It creates a library capable of encoding and decoding the complete EXI message set of the defined protocols.
You would greatly suppport this project if you are able to provide real-life EXI streams of ISO 15118-20 messages. We need these to validate the quality of the code. Any streams would be appreciated. Formats can be binary or hex-represented V2GTP messages, or just their EXI payload, or traffic captures (PCAP or PCAPNG). If possible, provide the corresponding expected content (e.g. as XML, JSON, or just a list of fields and values).
Please get in touch with the authors, or open a GitHub issue.
Thank you!
V2GTP is a protocol for "vehicle to grid" communication. It is used for control of power flow in charging electrical vehicles (EVs), for the communication between EV and EVSE (electical vehicle supply equipment, i.e. charging station).
The protocol is originally defined in the global standard ISO 15118. Its popular implementations are DIN 70121, ISO 15118-2, and ISO 15118-20.
The protocol is XML based, with the messages representable as XML, strictly defined using XML schemas. The message transfer uses EXI (Efficient XML Interchange), a compact binary representation of XML.
The codec is not implemented directly, but using this code generator, because the standards are evolving, yet share common ground. A code generator allows modifying a schema e.g. to implement experimental extensions, and allows creating a codec for future standard variants. The generator also aids in optimizing the code, by improving the EXI grammar evaluation, and by implementing configurations for limited protocol coverage for reduced code size, without the need to manually modify many places within the complete library.
The code generator takes the standards' XML schema files as input, analyzes them, and creates the appropriate codec representation.
This codec created by this code generator is designed to take a data representation of the message data - e.g. as structs or classes - and convert it to the binary EXI message representation, and vice versa.
The codec only abstacts the data representation. It does not enforce message order, message content (beyond what the XML schemas mandate) or other higher level requirements.
The code generator currently targets creation of C code, but can be expanded to support codecs in other programming languages.
The code generator requires Python 3.7. Furthermore, it requires the Python
module xmlschema and its dependencies,
especially jinja2. See requirements.txt
for precise details.
In order to be able to produce a codec, the standard's XML schema files are required. These cannot be distributed with the code generator. They are available within the actual standard documents, partly distributed separately by the ISO, and also available openly from other sources.
See the configuration files under src/config*.py. They include the paths
to the respective schema files, and also define output directories. They
also allow for specifying file and namespace prefixes, in case of creating a
codec which covers several of the named standards.
By inclusion or omission of certain schema files, features of the respective standards can be included or omitted (e.g. ACDP or WPT from ISO 15118-20).
The default configuration src/config.py is set up to build a codec for
both DIN 70121, ISO 15118-2 and ISO 15118-20, as well as appHandshake and
top-level V2GTP, with all their respective features. It uses schema files
in src/input/schemas/. It outputs the codec to src/output/c/, creates
logs in src/output/log/, and uses the prefixes appHandshake, v2gtp,
din, iso-2 and common for the respective codec folders, and similar
prefixes for functions and data types.
If the required Python dependencies are not already installed, run
$ python -m pip install -r requirements.txt
to install them.
To generate the codec, run
$ python src/main.py
If you have your own config, instead run
$ python src/main.py --config_file config_custom.py
The config file name should be an absolute path, or relative to the src/ directory.
Be sure to use your appropriate Python 3 (>= 3.7) interpreter.
The code generator and the resulting codec are licensed under the Apache License Version 2.0.