Resource vs Version model attributes

[duglin]

I think this might be related to @deissnerk's discomfort with our model...

• Right now it's not really possible to know for sure when a Resource attribute appears on the Resource or the Version. Version's isdefault and Resource's defaultversionid are examples.
• Similarly, because of this, we can't set the appropriate xxxRequired fields to true since depending on whether the client asks for a Resource or a Version the required-ness aspect will change.
• "exportrequired" is a horrible name :-)

I think we need to continue to have just Groups and Resources as part of the model definition itself. I think that 2-layer model is important to keep things simple and splitting Resources and Versions in the model will not only add to the perceived complexity but will require more work for people due to duplication of attribute definitions. However, I think we may need to be a bit more clear for client-side tooling.

Proposal:

• Add a Resource-level model attribute to indicate whether the property will appear on Resources, Versions or both. E.g. location, values = resource, version, both (appears on both but might not be the same value). Default value is versionso that user-defined extensions don't need to specify anything extra
• User-defined extensions MUST have a location value of version
• drop exportrequired

Need to think about how this relates to other model attributes, like "serverRequired" or "readonly"

Examples:	Attribute	location	readOnly	serverRequired	immutable
id	both	false	true	true
name	inherited	false	false	false
defaultversionid	resource	true	true	false
isdefault	version	true	false	false
user-extension	inherited	false	false	false
xref	resource	false	false	false
epoch	version	false	true	false
self	both	true	true	false
versionid	version	false	true	true

Then when we talk about "export" we can say:

• All attributes with a location value of both or resource will appear on the Resource
• All attributes with a location value of both or version will appear on the Version

Basically, we skip version attributes when exporting a Resource (i.e. don't show default Version attributes).

Are there other type of attributes I'm missing?

[duglin]

allow location=resource for administrative extensions (xref impls) to add, but not end-users since that would require code changes

[duglin]

Given the recent changes, I think we can reduce this down to: location=resource|version where the default value is version

to be clear, id and self will be version because they appear on both.

[duglin]

Going with location=resource|version|both