Extended metadata data model

[tliron]

In TOSCA 1.X metadata comprises a key-value map of strings to strings.

For TOSCA 2.0 we propose that metadata would instead use all types supported by the YAML 1.2.2 recommended schemas. Namely:

map, seq, str, null, bool, int, float

Our only restriction would be that the metadata keyname itself be a map.

Important notes:

• YAML map keys can be any value, not just strings. I propose to allow that full YAML expressiveness. This makes it easier for us because we don't have to add additional restrictions beyond YAML. Proper implementations of YAML parsers should support this.
• YAML does not specify the bit width of integers and floats but suggests that 32 bits should be acceptable.
• Users should be careful about the difference between parsing floats and integers. If they explicitly want a float, they should add ".0".
• Users should be careful with version strings being parsed as floats. E.g. "3.2" is a float but "3.2.1" is a string,

[lauwers]

New metadata grammar has been documented in TOSCA-v2.0-wd05-rev02