Hi Jody,
thank you for the feedback, please seem my answers bellow :-)
On Mon, 2020-01-20 at 15:49 -0800, Jody Garnett wrote:
> Nuno:
>
> 1) This is very similar to GeoServer 1.0 functionality that allowed
> attribute to be named, described, or hidden, ...
When GeoServer 1.0 was releases (~2003) I was still in high-school :D,
so I didn't use it and was not aware of that.
> 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?
Yes, with this extension point you will be able to define a
transformation, in the FeatureSource wrapper, that can handle queries
and map them has needed to the real attributes.
One of the use case I have for this is the following:
Often we deal with databases were for a reason or another simple
latitudes\longitudes are used and no spatial indexing is available, one
option here would be to create an SQL view but there is several cons,
e.g. no good indexing, negative impacts on heavily written tables, ...
I will later propose a community module that will make use of this
extension point,and will give us the option when configuring a layer to
generate a new geometry attribute on the fly from the latitudes and
longitudes:
* Clients will see a valid geometry attribute;
* GeoServer will translate the queries, transforming the geometry to latitudes
and longitudes ranged queries;
* This will give us the best of two worlds, GIS clients will see geometries,
the database will see latitudes \ longitudes (with the proper indexes)
Best regards,
Nuno Oliveira
> --
> 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.
> > 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
> > fax: +39 0584 1660272
> >
> >
http://www.geo-solutions.it> >
http://twitter.com/geosolutions_it
> >
> >
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>
--
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
fax: +39 0584 1660272
http://www.geo-solutions.it
http://twitter.com/geosolutions_it
-------------------------------------------------------
Con riferimento alla normativa sul trattamento dei dati
personali (Reg. UE 2016/679 - Regolamento generale sulla
protezione dei dati “GDPR”), si precisa che ogni
circostanza inerente alla presente email (il suo contenuto,
gli eventuali allegati, etc.) è un dato la cui conoscenza
è riservata al/i solo/i destinatario/i indicati dallo
scrivente. Se il messaggio Le è giunto per errore, è
tenuta/o a cancellarlo, ogni altra operazione è illecita.
Le sarei comunque grato se potesse darmene notizia.
This email is intended only for the person or entity to
which it is addressed and may contain information that
is privileged, confidential or otherwise protected from
disclosure. We remind that - as provided by European
Regulation 2016/679 “GDPR” - copying, dissemination or
use of this e-mail or the information herein by anyone
other than the intended recipient is prohibited. If you
have received this email by mistake, please notify
us immediately by telephone or e-mail.
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