Re: [cmis-comment] Property ID uniqueness

[Al Brown <albertcbrown@us.ibm.com>]

Raphael brings up an interesting point that I feel requires discussion before responding.

There are two use cases on the property definitions that are important:
1. Property Definitions are stored separately from type definitions and then applied/added to type definitions. In that scenario those fields would not be different if the same backing property is used.
2. Property ID conveys semantic equality such that a client can determine if property x (title) is the same as property y (name) on different type definitions.

Since CMIS dictates the object id for the base properties, in particular cmis:name, cmis:objectId, cmis:objectTypeId, cmis:baseTypeId, cmis:createdBy, cmis:creationDate, cmis:lastModifiedBy, cmis:lastModififcationDate, and cmis:changeToken. Out of those, I would expect cmis:name to be the most likely one to use different backing properties. With FileNet, we map two different properties to cmis:name - one for folder and one for documents. I believe the lengths are the same in the FileNet case though.

We have gone through the various proposals on property definitions and now have id, localName/localNamespace, displayName, and queryName. Out of those, only is used for references and is mandated by CMIS specification.

I would propose that use case #2 (semantic equality) be moved from property ID to localName/localNamespace. I would also state that a property definition can change (max length, etc as described below) between type definitions. That seems in line with the original intent of the statement highlighted.

Thoughts?

-Al

Al Brown
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Email albertcbrown@us.ibm.com
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Raphaël Jean ---01/16/2010 03:24:00 AM---Section 2.1.3.3.2 of the spec states that the Property ID "uniquely identifies the property in the r

From: Raphaël Jean <raphael.jean@entropysoft.net>
To: <cmis-comment@lists.oasis-open.org>
Date: 01/16/2010 03:24 AM
Subject: [cmis-comment] Property ID uniqueness

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Section 2.1.3.3.2 of the spec states that the Property ID “uniquely identifies the property in the repository.  If two Object-Types each contain property definitions with the same ID, those property definitions are the same.”
But some standard CMIS properties, such as cmis:name, are defined on all Object-Type hierarchies (document, folder, policy, relationship). Now, on many systems, the property definition of cmis:name for example, will differ for folder, document and other types: localName/localNamespace, maxLength, etc. will be different.
 
Shouldn’t the uniqueness scope of a Property ID be a single Object-Type hierarchy instead?
 
Thanks,
 
Raphael Jean
CTO
EntropySoft