Paul Ramsey a écrit :
> But, in the long term, what is the correct design way to handle
> this? we have the "real" EPSG database, which will presumably be
> updated over time, to include more and more projections as EPSG does
> their work. And we have some projection numbers like the ESRI and
> Cubewerx ones, that were pretend standards, but exist in legacy
> software in lots of places. And we have the global useful ones,
> which might also exist in legacy places (ESRI has a number for world
> mercator, for example) which would be hand to have around.
I already though about this issue and created a JIRA task for that a few months
ago:
http://jira.codehaus.org/browse/GEOT-774
The proposed fix, already available on trunk, is "FallbackAuthorityFactory"
(note that I'm not sure
that this name is really correct). This is a factory which delegates all object
creation to a main
factory, and fallback on an other one if the main factory failed. So
"FallbackAuthorityFactory" can
delegates object creation to epsg-hsql (for example) and fallback on epsg-wkt
if the former failed.
There is a few additional work needed before this proposal can work:
1) I would like a new module, said "epsg-ext", "epsg-esri" or whatever, which
is a
copy of "epsg-wkt" containing only the additional CRS. All CRS available
through
epsg-hsql would be removed from epsg-ext.
2) We would need to decide what axis order should be for the GeographicCRS
declared
in epsg-ext. Lets remind that even if axis are declared as
(latitude,longitude)
in epsg-ext, users can force (longitude,latitude) using the same mechanism
(hint
or system property) than epsg-hsql.
3) The AuthorityFactory class in epsg-ext need to be a subclass of
"PropertyAuthorityFactory",
and this module must register a "FallbackAuthorityFactory". I can take care
of this step if
the above is done.
Does is sound like a pratical approach?
Martin.
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