GeoAPI wrappers for GeoTools

[Martin Desruisseaux <ma...@geomatys.com>]

Hello all

During the OGC meeting in Rome this week, a proof of concept of what may 
be CRS-JSON (for discussion purposes only, not an approved standard) has 
been demonstrated. In order to show that the CRS-JSON prototype works 
with different implementations, GeoAPI wrappers for GeoTools have been 
created. Those wrappers allow GeoTools users to view the metadata and 
referencing services as a GeoAPI implementation. Doing so provide the 
following benefits:

  * For peoples who were using GeoTools before the package renaming to
    "org.geotools.api", it allows them to continue to use the
    "org.opengis" package names, but this time compliant with the OGC
    standard.
  * It allows to use GeoTools with the above-cited CRS-JSON prototype
    (demonstrated at the OGC meeting this week) and with GIGS tests.
  * It allows users to switch more easily between implementations
    (currently Apache SIS, GeoTools and PROJ) as they need.

The wrappers are bidirectional: users can view GeoTools objects as 
GeoAPI objects, or the converse. The converse should, in theory, allows 
to use alternative implementations such as Apache SIS and PROJ inside 
GeoTools. However, I didn't tested.

I tried to make the wrappers as complete as I could. It covers pretty 
much all the GeoTools API that I could map to GeoAPI. The wrappers 
include the factories. In particular, the two following methods are 
available, but returning the GeoTools factories viewed as GeoAPI factories:

  * CRS.getAuthorityFactory(longitudeFirst)
  * CRS.getCoordinateOperationFactory(lenient)

The project is there: https://github.com/Geomatys/geoapi-gt-wrappers

The JAR file has not yet been deployed on a Maven repository, but we may 
deploy it to https://maven.geotoolkit.org/ (waiting first to see if 
there is feedbacks). A better location would be the OSGeo repository, 
but OSGeo declined a few months ago a proposal to have this project 
hosted in their foundation. If a volunteer is willing to ask again 
later, I would be happy to transfer the ownership to OSGeo, including 
the copyright if desired.

     Martin