Custom configuration format(s) used by CSE

[markaren]

Discussion about the configuration format that is/should be used by CSE for:

• msmi
• scenarios
• orchestration
• other?

[ljamt]

As the msmi files and the co-simulation configuration are related, these should be in the same format. The scenario files will probably be handmade and should be in a format that is easy to work with for humans.

As the other workpackages are about to start using the MSMI files proposed in PR #333 and implemented in the msmi-validator and cse-configurator we should settle it sooner rather than later.

xml

• pros
  • schema validation
  • FMI, SSP and DCP are based on xml
  • widely supported, excellent tooling
• cons
  • verbose
  • less human readable than json/yaml

json

• pros
  • schema validation
  • widely supported, excellent tooling
• cons
  • Nan/Inf not supported
  • comments are unsupported

yaml

• pros
  • schema validation
  • can parse json
  • anchors are well suited for scenarios
  • more "human friendly" than json and xml
• cons
  • less supported than xml and json (but still very good support in C++/Java)
  • some people dislike the python like indentation

[markaren]

My recommendation:
Use YAML for files that humans will interact with (scenarios). This option also allows JSON to be used, since YAML is JSON. Users can decide for themselves which they use.

For other files use XML in combination with .xsd files.

[lassebje]

Humans may interact with scenarios today, but will also be handled by tools most likely.
I think we should choose one format for everything in that respect so that every format can be specified in the same schema language, be it xsd, json schema or YAML schema. Any of the suggested formats seem appropriate and they are "interchangeable" seen from the computer. I have no strong opinion other that we choose the same for all.

[mrindar]

My two cents:

1. All input files will be handled by computers - both read and write. I think this should make us lean more towards the format which has the best schema support, and the best availability of parsers/generators across 'all' languages
2. Having the same file format across 'everything' is appealing

[ljamt]

After discussion in "mob session" and taking in all your arguments, we conclude using xml for the msmi-file and the co-simulation configuration. As the scenario files often will be written by humans, these files should be json or yaml.

Let me know if you strongly disagree :)

[markaren]

Sounds good to me. XML is pretty decent coupled with xsd since you get on the fly input validation in IntelliJ/CLion and for Java you get superb code generation through JAXB.

Regarding json and yaml: Remember that they are not mutually exclusive. Choosing yaml means json is also supported :). There are proabably some cavecats, but I think the two main yaml parsers for C++ and Java can handle both.

[lassebje]

Fine by me. IF human interaction is important in the scenario file, you should choose yaml.