Jody Garnett <[EMAIL PROTECTED]> wrote on 11/14/2006 02:00:00 PM:


> > It sounds like you want to be able to write code to manipulate and
query a
> > Java Data Product Specification, and write adapters from a particular
> > incarnation of that data product to the specification.
> >
> > I think it's a good idea.  I think you can make a Data Product Mapper
which
> > could offer the human user the opportunity to connect concepts from the
> > data product specification to the actual data in the data store.
> > Presumably they could save a particular mapping for later use, and
perhaps
> > trade it with their friends.  I'm pretty sure that automated mapping
would
> > be hard.
> >
> I am hoping that it would not be a question of automatic mapping; only
> of mapping in an operation when specific properties are available
> (specific to the point of exact match? or specific in terms of derived
> attribute? answer is the "Trait" probable has to let us known know the
> rules of where it can be applied).

If we have human-directed mapping first, maybe we can use it enough that we
learn how to write an automated mapper.  Right now I don't think it's an
option.

> a) your poor brain

sniffle.

> b) not sure you can call an operation with this system (it is only used
> to filter out content, which you could then call an operation with)

ah, I'll stop trying then.

> c) the property tag has probably been appropriated to mean data access
> in the context of filtering
> d) the expression interface is what we went to great lengths to preserve
> with our feature model work (being sure that the same xpath could be
> used to navigate the object model and the xml model)

We need a nomenclature standard. ;)  Property means any of attribute,
association, or operation unless we're in Filter land, where it means only
attribute.  got it.

Here's the big question: Do you intend for Filter/Expression to operate on
individual range values of a coverage?  Or should Filter/Expression be
limited to operating on Coverages themselves (not the spatially varying
data).

Corrolary: Does Filter/Expression operate on "Properties"/attributes which
are Lists/arrays, and how are these arrays indexed?

> e) you can write code, a BNF is also available

yeah, baby.  Looking.


> > In the GeoAPI Feature interface, what is putClientProperty?  Does that
add
> > a named property to the feature or does it set the value?  Does setting
the
> > value of an operation make any sense?  Would that mean setting a
functor
> > object to actually perform the operation?
> >
> putClientProperty is for exactly what it says in the javadoc - giving
> programmers a place to store their
> crap so we do not see tones of code with Map<FeatureType,Object>.

How is this different than adding an attribute to the FeatureType (and
subsequently to all Feature instances)?  Is this a mechanism intended to
allow freeform annotation of individual Feature Instances?  Or to allow
Features with different attributes to share a common FeatureType?  Is this
crap part of the Feature and stored with it?

If it's not related to a Feature Property (Attributes, Associations, and
Operations), I think it might be best to find another name for it.  The
"crapKubby" comes to mind.

While we're talking about GeoAPI interfaces, can we do a global search and
replace?  Opperation -> Operation (and lowercase version of same).

> > I guess let me start small and slow: how do I call an operation if my
> > starting point is an org.opengis.feature.Feature?
> >
> Yeah! This is a dicussion I have wanted to have with you since February:
> AS IT STANDS NOW
> ------------------------
> 1. grab the feature type from the feature
> 2. navigate through the model to find the operation you want for that
> feature
> 3. invoke the operation with the feature as the first parameter, and the
> remaining arguments following

Icky.

> WHAT IT SHOULD BE
> --------------------------
> 1. grab the feature
> 2. feature.invoke( operationName, arg1, arg2, ... )

Yeah baby!  When do we get this?  This appears to be an easy score.  Is
there hidden complexity which prevents us from writing a Feature.invoke()
method which does the 3-step process in "AS IT STANDS NOW"?

> > > [snip]
Let's table the discussion of tabular data for now...

> >> Well if you want have a look at RasterSymbolizer (the point of contact
> >> between coverage and expression) and then we can have a nice IRC chat.
> >>
> > I think I need coffee. :) Learning sucks.
> >
> We can always cheat, simone should of looked at raster symbolizer
> perhaps he can answer questions on the subject.

RasterSymbolizer is a portrayal concern.  We may very well have different
implementations of it for a generic grid point coverage and for the special
case of 2D data.  To be efficient, it probably needs to know the
implementation details of a particular coverage implementation.  We're
probably not going to have just one.

To be honest, I'm not thinking that far ahead yet. :)

Bryce


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