Hi Andrea,
thanks for the feedback, please see my answers bellow:
On 03/20/2018 10:21 AM, Andrea Aime wrote:
Hi Nuno,
last time a new type of filter was in this commit:
https://github.com/geotools/geotools/commit/47e9259d74482b92244b4dd301363b434e382baf
Thankfully now there are default methods, allowing for quite a bit less painful
extension.
Thanks, yes default methods help indeed.
Overall I see where this need comes from and agree with it, a few notes/questions off the top of
my head:
* Can you share how you intend to implement NativeFilter? Is it an interface
with store specific
implementations, or does it have a single one? Which stores will receive a
sample
implementation of the concept?
My idea is to create an interface (this will help with filter visitors):
public interface NativeFilter extends Filter {
Expression getNative();
}
and then provide a default implementation for it, this default implementation should be enough for
most use cases.
The JDBC data store will be the first one receiving support for it.
* Make sure the functionality is open for programmers but not from the web
(e.g., one cannot
setup a XML or CQL filter using it
Yes this is an important point indeed, no XML binds or CQL support will be implemented. The Filter
to CQL visitor will throw an exception.
* Properly document the intended usage of it including notion of pre/post
filter splitting,
e.g., if a NativeFilter is supported, but it's OR-ed with another bit using
an unsupported
filter function, it will end in the post, in memory evaluation, and will
blow up.This is
unavoidable, but should not be a surprise for users.
Yep.
Cheers
Andrea
On Mon, Mar 19, 2018 at 11:07 PM, Nuno Oliveira <nuno.olive...@geo-solutions.it
<mailto:nuno.olive...@geo-solutions.it>> wrote:
Hi all,
Recently I have been dealing with some use cases that require the ability
to inject some
native filters,
specific for each feature type and non static over time, to the final
native query build by
GeoTools and
send to the data store.
For example, the content of a feature type is partially controlled by an
external service who
provides a non
static native query (the request changes over time) that filters the
content that should be show.
Another use case is a complex authorization rules system where the
authorization rules are SQL
expressions that need to be append to the final SQL WHERE clause build by
GeoTools, the system
provides SQL expressions for different databases (Oracle, PostgreSQL,
MySQL, etc ...).
Most of the native filters of this use cases are quite complex and can't be
translated to OGC
filters.
Since we have a pattern here that can be applied to several use cases and
data stores I have
think about
an approach that would allow extensions, external code, etc ... to inject
the necessary native
filter(s)
and allow data stores implementations to handle those native filters in an
harmonized way.
I have come up with the idea of a new filter named /NativeFilter/:
* this filter will NOT be directly usable by the final users, for example
in WFS requests
* if any code try to evaluate it in memory an exception will be throw
* it will not break any API and data stores will be free to implement is
support has needed
* it will have a method getNative() that will return a String containing
the native filter
A new default method would need to be added to the /FilterVisitor/
interface and a default
implementation would need to be added to /AsbtractFilterVisitor and
DuplicatingFilterVisitor /
classes (like for any other filter).
The data store who wants to supports this filter will need to extends it
custom visitor, for
example,
for relational databases we only need to add a new visit method to
/FilterToSQL/ visitor.
This gives the necessary flexibility for third party code (codes that use
GeoTools) to inject
native
filters without any specific extension points or cumbersome handling. It is
also worth notice
unless
some code is using native filters this will have no impact on other usages.
Any thoughts on this ? Objections ?
King regards,
Nuno Oliveira
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Regards,
Nuno Oliveira
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55054 Massarosa (LU)
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Conservare il messaggio stesso, divulgarlo anche in parte, distribuirlo ad altri soggetti,
copiarlo, od utilizzarlo per finalità diverse, costituisce comportamento contrario ai principi
dettati dal D.Lgs. 196/2003.
The information in this message and/or attachments, is intended solely for the attention and use
of the named addressee(s) and may be confidential or proprietary in nature or covered by the
provisions of privacy act (Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection
Code).Any use not in accord with its purpose, any disclosure, reproduction, copying, distribution,
or either dissemination, either whole or partial, is strictly forbidden except previous formal
approval of the named addressee(s). If you are not the intended recipient, please contact
immediately the sender by telephone, fax or e-mail and delete the information in this message that
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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
-------------------------------------------------------
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il destinatario, Vi preghiamo cortesemente di darcene notizia via e-mail e di
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sistema. Conservare il messaggio stesso, divulgarlo anche in parte,
distribuirlo ad altri soggetti, copiarlo, od utilizzarlo per finalità diverse,
costituisce comportamento contrario ai principi dettati dal D.Lgs. 196/2003.
The information in this message and/or attachments, is intended solely for the attention and use of the named addressee(s) and may be confidential or proprietary in nature or covered by the provisions of privacy act (Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection Code).Any use not in accord with its purpose, any disclosure, reproduction, copying, distribution, or either dissemination, either whole or partial, is strictly forbidden except previous formal approval of the named addressee(s). If you are not the intended recipient, please contact immediately the sender by telephone, fax or e-mail and delete the information in this message that has been received in error. The sender does not give any warranty or accept liability as the content, accuracy or completeness of sent messages and accepts no responsibility for changes made after they were sent or for other risks which arise as a result of e-mail transmission, viruses, etc.
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