Advancement of DarwinCore postponed on standards track
sblum at CALACADEMY.ORG
Wed Sep 28 17:30:55 CEST 2005
Advance of DarwinCore postponed.
A surprise at the recent TDWG annual meeting was the withdrawal of
DarwinCore2 from the ballot of standards up for recommendation. This was
done because recent changes need more time for review and explanation; it
does NOT mean that support for the DarwinCore has been withdrawn, nor does
it mean that we have to wait until next year to finalize the schema. With
some diligent work over the next two to three months, we can finalize the
DarwinCore2, test it, and begin broader deployment. If you are a current or
potential user of the DarwinCore, please note that additional work needs to
be done and your participation would be appreciated. The longer version of
what transpired in St. Petersburg follows below.
On July 10th, more than 60 days before the annual meeting as prescribed by
the TDWG bylaws, John Wieczorek and I posted a revised version of the
DarwinCore2 on the review web site
This draft incorporated the advisable changes proposed since the draft of
October, 2004. We then informed the TDWG Executive Committee, that the
DarwinCore2 was ready to be considered for recommendation as a full TDWG
On September 12th at the annual meeting, conveners of the respective
subgroups presented their proposed standards in a plenary session. I
summarized the current state of the DarwinCore2, the changes made since last
year, and the rationale behind them. The most significant change was to
remove the geospatial elements from the core and place them in a geospatial
extension. We did this for two reasons: 1) to follow the emerging best
practice of constructing schemas to be interoperable across domains; and 2)
to improve the stability of the core by making it smaller. Unfortunately,
this change caught many people unaware, and serious questions were raised in
the discussion period. These questions and my responses to them are
1) Geospatial elements are critical to many users of the DarwinCore, so why
Response: There is broad agreement among data architects, within TDWG and
beyond, that the best way to achieve interoperability across domains is to
import external schemas (and thereby the elements they contain), for
example GML, rather than redundantly defining conceptually equivalent
elements in our own namespace, as we have done in the past. An alternative
we did not discuss, but will consider in the coming weeks, is whether a
better strategy would be to import the GML elements directly into the core
rather than putting them into an extension. In any case, we are certain
that the DarwinCore, or application schemas based on the DarwinCore, will
import their geospatial elements from GML.
2) These critical geospatial elements are now relegated to a specification
that is not at the same level of maturity as the DarwinCore. Is this a good
thing to do?
Response: This will be inevitable if we develop our information domain by
solidifying the areas with greatest commonality and defer more specialized
elements to subsequent work by appropriate stakeholders.
[A point I didn't make at the meeting, but would like to make now is that
GML is actually more mature, or at least more broadly deployed, than any
TDWG standard. So the elements in the geospatial extension are more stable
than the DarwinCore, not less stable.]
3) Can the geospatial extension include the GML elements for lines and
polygons as well as those for points?
Response: This will need further investigation, but would certainly be
desirable in the long run.
Another cautionary marker appeared the next day among the contributed
papers. Roger Hyam gave a presentation about managing change among
interdependent schemas. He described a situation in which version
dependencies among schemas could require them to be upgraded simultaneously,
which effectively eliminates the main benefit of separating them in the
first place. Gregor Hagedorn challenged the generality of Roger's point
saying that proper referencing of schemas could ensure the required
flexibility. The issue was left open and obviously requires further study
and resolution, preferably in the form of a recommendation from a group of
technical architects to the groups constructing references among schemas.
As the deadline approached to open the vote on standards up for
recommendation, both Adrian Rissone and Walter Berendsohn approached me
(Stan) separately and asked me to withdraw the DarwinCore from the ballot.
Both of them said that people had expressed to them the opinion that the
recent changes to the DarwinCore were too large relative to the earlier
draft, and too recent to warrant putting the schema up for recommendation as
a standard. Although I believe the DarwinCore would have received at least
the required simple majority of votes, in the interest of broader consensus
I agreed to withdraw it from the ballot. Therefore, at the beginning of the
final session on Tuesday I "announced" that we had agreed to take the
DarwinCore off the ballot while the larger architectural issues were
settled. I went on to explain that in my judgement the best course of action
would include the following tasks:
1) convene technical experts to develop an explicit recommendation about
how to incorporate elements from one schema into another (i.e., to address
the issue Roger Hyam raised);
2) work with the various DarwinCore user communities to determine the most
appropriate allocation of elements to the core and its extensions, producing
explicit lists of elements that would be available to each specialist
community by constructing their schema from the core, GML, and their own
3) resolve these issues as quickly as possible (2-3 months), and fix the
resulting draft as version 2.0;
4) Develop explicit instructions for upgrading providers with DarwiCore2
and begin testing.
At the end of the discussion I asked for vocal expressions with agreement or
disagreement for withdrawing the darwincore from the ballot. About 10
people voiced support for withdrawing it from the ballot, no one expressed
disagreement, and most were silent (perhaps stunned). It was done, and now
the work goes on.
An architecture interest group is being established and will be announced on
the main TDWG mailing list. Roger Hyam will lead that group until more
formal arrangements are made.
Finally, I want to point out some problems we have had with group dynamics.
I was too busy this last year to devote sufficient time to promoting
discussion and developing consensus. Things are only going to get worse for
me with the need to revise the general TDWG standards development process.
Therefore, John Wieczorek and Renato de Giovanni are going take over
managing the DarwinCore, though I will do my best to continue to
participate. I think passive publishing (e.g., via a web site or wiki) is
ineffective if the tempo of contributions is episodic. People stop visiting
the web site when activity drops off, and they don't come back unless
something is pushed into their inbox. Therefore I would like to encourage
stakeholders in the DarwinCore to subscribe to the email list. Instructions
can be found at http://circa.gbif.net/tdwg.
We will do our best to respond to your concerns and keep the discussion moving.
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