Nuno:
1) This is very similar to GeoServer 1.0 functionality that allowed
attribute to be named, described, or hidden, ...
2) Do you need more information to handle the query efficiently? I had for
some time wished to see a "java view" created with a UI similar to "sql
view" making use of the transform process. Sadly this is a little complex
due to the need to reverse any transformation, mapping a query back to the
original data source. Does your " RetypeFeatureTypeCallback" also need to
process queries?
--
Jody Garnett
On Mon, 20 Jan 2020 at 14:31, Nuno Oliveira <nuno.olive...@geo-solutions.it>
wrote:
> Dear all,
> long story short, I would like to propose adding a new extension point in
> ResourcePool that would allow extensions to retype a feature type, and
> consequently change the associated features.
> In practice it would allow us to create extensions that would be able to
> add\hide attributes, generate new attributes or even just change the values
> of existing attributes.
>
> For those wondering if the current FeatureTypeCallbacl [2] doesn't allow
> us already to do that, the answer is no :)
> FeatureTypeCallBack allow extensions to initiate, and manage, feature
> types that are generated based on user provided information, for example,
> SQL views or Solr feature types, but not to change existing types or
> features.
>
> The extensions code would be executed here [3] and here [4], when a
> feature type is build (buildFeatureType) and when the source for a feature
> type is returned (getFeatureSource).
> The later would allow us to wrap a feature source, setting the feature
> type we want and\or apply the wrappers we want to the future stream of
> features.
>
> I'm proposing the following interface for the extension point:
>
> /**
> * Extension point for {@link ResourcePool} allowing us to retype an
> existing {@link FeatureType},
> * and to rearrange the features produced by the correspondent {@link
> FeatureSource} by wrapping it.
> * This extension point can be, for example, used to add a new attribute
> or remove an existing one.
> * If the intend is instead to create a new feature type, the existing
> {@link FeatureTypeCallback}
> * extension point should be used.
> */
> public interface RetypeFeatureTypeCallback {
>
> /**
> * Gives a chance to this callback to retype the provided feature
> type, if this callback has no
> * interest in retyping the provided feature type, then the unchanged
> provided feature type
> * should be returned. NULL should never be returned.
> *
> * @param featureTypeInfo non NULL GeoServer feature type info
> * @param featureType non NULL GeoTools data source feature type
> * @return retyped feature type or the unchanged provided feature type
> */
> FeatureType retypeFeatureType(FeatureTypeInfo featureTypeInfo,
> FeatureType featureType);
>
> /**
> * Gives a chance to this callback to wrap the provided feature
> source, if this callback has no
> * interest in wrapping the provided feature source, then the
> unchanged provided feature source
> * should be returned. NULL should never be returned.
> *
> * @param featureTypeInfo non NULL GeoServer feature type info
> * @param featureSource non NULL GeoTools feature source
> * @return wrapped feature source or the unchanged provided feature
> source
> */
> <T extends FeatureType, U extends Feature> FeatureSource<T, U>
> wrapFeatureSource(
> FeatureTypeInfo featureTypeInfo, FeatureSource<T, U>
> featureSource);
> }
>
> If this extension point is accepted, we would also like to backport it to
> 2.16.x, opinions are welcome :)
>
> Kind regards,
> Nuno Oliveira
>
> [1]
> https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/catalog/ResourcePool.java
> [2]
> https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/catalog/FeatureTypeCallback.java
> [3]
> https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/catalog/ResourcePool.java#L1114
> [4]
> https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/catalog/ResourcePool.java#L1393
>
> --
> Regards,
> Nuno Oliveira
> ==
> GeoServer Professional Services from the
> experts!
> Visit http://goo.gl/it488V for more information.
> ==
>
> Nuno Miguel Carvalho Oliveira
> @nmcoliveira
> Software Engineer
>
> GeoSolutions S.A.S.
> Via di Montramito 3/A
> 55054 Massarosa (LU)
> Italy
> phone: +39 0584 962313
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