Ok, I've submitted a request for an account on Confluence.
> Q: is it really called an SQL projection? I would of considered it an SQL
> function or data transform with SQL :)
> A: yes it is - http://www.postgresql.org/docs/6.5/static/sql-language.htm
>
> In that case we are going to have fun naming these new methods for the
> Query object.
>
There are a lot of overloaded terms here. Of course, projection can mean
spatial or relational. Alternatives are 'mapping' (also overloaded) or
'transformation'. I think transformation is the least confusing and
already exists in the geotools API.
>
> Q: Do we represent projections using CQL (like in Transform) or using
> XPath (like in WFS)?
>
> WFS 2.0 Research: WFS 2.0 has Minimum XPath and Schema Element Function.
> Appears to only use a subset of XPath which does not look like it supports
> functions. They have examples such as
> *addresses/Address[street="Oxfordstrasse"]/number* used to select a
> specific element out of a list.
>
I tried digging around in the various specifications. I believe you are
correct; WFS requires only selection of complex attributes in GML via
XPath, not transformation functions.
I like the idea of ECQL because its simple, extensible, and already
implemented in gt-transform. It's the least surprising to developers.
Also, we could potentially support XPath as in any value reference within
ECQL defined transformations (perhaps that already exists?).
-Anthony.
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