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As to
your gjxdm comments:
1)
There are many positive things to be said for the justice data dictionary; fewer
for the data model. Let's remember that there are two work products, each having
their own value.
2) I
believe that SuperType is one example of less than ideal "object oriented
modeling" and that much improvement could be made in this area. I also agree
with your naming convention comments although I will continue to hold out hope
that we can call "core" elements by a common name across multiple
domains.
3)
Some time ago I broke up the full jxdm schema into individual "objects" -
one object per complex type. I found (as did others) the individual objects
to be valuable and much easier to work with when not constrained by the
hierarchy imposed by the full model. In local domains we were able to
create "core" definitions for individual objects. The subset generation tool
allows users to create similar results as using the "objects" but retains
the constraints of the full model and does not allow reuse of individual object
definitions. I believe a key to success in commonality is to match
individual components of each of the definitions, not constrain thinking to
the larger models. This, of course, begs the question "What is
an individual component?"
I wish
you luck and will eagerly participate in cross domain discussions as long
as the response to suggested changes is not "It's valid XML" and you do
not refer to independent, objective thought as "not invented
here."
A
question: What is the definition of a domain and how many domains should be
considered? Is this discussion beyond the scope of this TC (or any individual TC
for that matter) and if so, where should the discussion take place? I would hope
that minimally the court filing and integrated justice TCs would also
participate in cross domain discussions relative to core definitions. Are there
others?
gary
Hi Everyone,
Before I dig into specifics, let
me state three things in relation to the previous email thread on the
“emergencyType” differences.
- As a developer myself, I always
believe technical issues trump politics, turf or bias. I am always
happy to keep discussions at the technical level.
- This is a good time for this
discussion because we need to resolve best practices on reuse of a set of
core XML Schema types across domains. My current thought is that GJXDM
may have defined most of those core types so we need to determine how to
separate them from any domain-specific content. This work has
ramifications both within this group and externally to other efforts under
way. From my reading of the TC requirements document, though I
disagree with its definition of “core” (more on that below), this seems to
be inline with the section on EM Core and Metadata Standards.
- Relating specifically to GJXDM,
my discussions and experience with the OJP folks is that they are very
willing to work with people to improve the model. That, of course,
brings us back to focusing on technical issues on any deficiencies on GJXDM
and not vague difficulties like the size of the model or preferences in
naming rules.
So, now focusing on
specifics:
First, some thoughts on
“emergencyType”:
There are two separate issues here under
consideration: the naming design rule and the difference in modeling
approach. The naming design rule is debatable and probably arbitrary as
long as your naming is consistent. The modeling approach and semantic
differences between the concepts is, in my opinion, the more important
issue.
To me, the first thing to get consensus on is how we
model an event. In the Distribution schema you use an event type
enumeration; however, in the CAP schema you are using a
string. One problem in this setup is that you could not validate before
hand whether the event type in the distribution header was the same as (or
compatible with) the description of the event in the CAP message. In
comparison to GJXDM, an event type code to distinguish events could be modeled
as a constraint on the event name or as another attribute in the GJXDM Event
Type (akin to a Class). Or, if the event types are significantly
different you may want to extend Event Type to add attributes. For
extensibility and flexibility, I would prefer an Event as a Class with an
optional category property to classify (or categorize) the event within a
taxonomy. In recognition of the fact that there may be other existing
taxonomies that people want to categorize their events under, the
“EventCategory” element should have a qualifier attribute, possibly called
“source”, to identify an external classification scheme (as is done in ebXML
and UDDI registries).
Some thoughts on
GJXDM:
- I am not part of DOJ and have no
bias toward this group accepting or rejecting the work. In my opinion,
it should stand or fall on its own merits. However, having said that,
my examination of it so far has been mostly positive.
- I have minor issues with some of
the naming, for example “SuperType” for the root of all content types is not
in line with object-oriented modeling where a “SuperType” is any Type
“above” (or parent of) the current type. However, naming is something
that is just not worth debating over. In my opinion, the way to handle
naming is to separate the labels from the concept identifier. As in
OWL or topic maps, you should allow multiple labels (or names) for a single
concept as long as the concept has a single unique identifier.
- The key modification to GJXDM I
would like to see is for it to be more modular. I am meeting with OJP
and the Georgia
Tech folks
in January to discuss this in more detail. Your thoughts and input in
this area would be very beneficial. The most important area of
modularity is distinguishing between core entities and domain-specific
ones. I define “core” as any data element that crosses more than one
domain. Within that set, I call “universal core” those entities that
cross all domains. Thus, at a minimum, you would have two “core”
schemas (universal core and “domain-intersections” or “Community of Interest
(COI) core”) and then domain-specific schemas. Given the above, reuse
would involve extending core entities to create domain-specific
entities. One business use case for this is that a federated query
would be able to span all core entities across domains.
Other miscellaneous
thoughts:
1. On the Distribution schema –
what is the functional requirement for this? I say that especially in
light of the fact that it is an optional element in the Standard Message
Format document. If the business case was strong enough, I would not
think this would be optional. In general, I like the concept but am
concerned that such a potentially complex issue should be designed after a
clear articulation of the functional requirements we are trying to
solve. Especially, when some could argue that distribution should not be
determined by the originator but dynamically based on a publish/subscribe
approach (with proper authentication). Also, there seems to be some
overlap between the elements in CAP and the elements in
the distribution schema.
Well, that’s enough for now.
I look forward to working with you on these issues.
Regards,
Michael
C. Daconta
Metadata Program
Manager
Department of Homeland
Security
tel: (202)692-4340
email:
michael.daconta@dhs.gov
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