A "layered" model for interoperability using Dublin Core metadata
Mikael Nilsson has circulated (to the DCMI Architecture forum mailing list) a short draft document titled Interoperability levels for Dublin Core metadata. The document is a result of both the discussions around the relationship of the DCMI Abstract Model and RDF which surfaced around a series of posts by Stu Weibel a few months ago, and also the longer running efforts within DCMI to reconcile the use of the term "Dublin Core metadata" to refer both to data created within these formal frameworks and to data created using less formal, more ad hoc approaches.
The document presents a "layered" approach, describing four distinct "interoperability levels", each building on the previous one, and attempting to specify clearly the assumptions and constraints which apply at each of those levels, and the expectations which a consumer can have for metadata provided "at" a specified level.
- Level 1: "Informal interoperability", based essentially on the natural-language definitions of metadata terms;
- Level 2: "Semantic interoperability", based on the RDF model;
- Level 3: "DCAM-based syntactic interoperability", introducing the notions of descriptions and description sets, as defined by the DCMI Abstract Model;
- Level 4: "Singapore Framework interoperability", in which an application is supported by the complete set of components specified by the Singapore Framework for Dublin Core Application Profiles
As Mikael notes in his message, this is an attempt to articulate some of the notions which have underpinned developments in DC metadata over the last few years. One of the difficulties we've had, I think, is that in some of our conversations within DCMI, parties in the discussions have been adopting viewpoints reflecting different "levels" in this model (particularly level 1 on the one hand and levels 2 or 3 on the other, I think) and perhaps "talking past each other" as a result. So any attempt to try to articulate these differences, and to make explicit our implicit assumptions, is to be welcomed, I think.
It should be emphasised that this is a very early working draft circulated for discussion, and there is no community consensus on these concepts. Comments on the draft should be sent to the DC-Architecture mailing list. (While I'm not going to close comments on this post, I'd strongly urge you to send comments to that list, so that discussion is visible to members of that forum.)