[mapserver-dev] spatial restriction for queries

[Tamas Szekeres]

2009/10/3 Martin Kofahl <m.kofahl at gmx.net>

> What is your (and other MapServer devs') opinion about a having a spatial
> access control system inside MapServer?
>
>
Martin,

I admit I haven't studied all aspects of this proposal, but it looks like as
it would be an example of an "extension layer" addressed by one of my
previous RFCs,
http://mapserver.org/development/rfc/ms-rfc-22a.html

(Note: The title of this RFC doesn't completely reflect the proposed
concept, the feature cache would only be just one simple usage example of
that. I should probably rename this RFC to something like: "Support to
implement extension layers").

In this case the the layer would be defined in a cascaded fashion in the map
file. The outer layer would be able override the vtable functions of the
inner layer, therefore a subset of the features could also be hidden
according to a custom logic when displaying the whole layer. I this regard,
it wouldn't be required to define 2 sibling layers (which is quite annoying
here), the outer layer would contain the select shape, and the vtable
functions could eventually implement reading the env variables as required.

In case if this common infrastructure would exist in MapServer, then you'd
only require to write your custom layer data provider (ie. the vtable
functions of a new layer type) which could eventially be a plugin
(independent from the mapserver codebase).

By all means, my preference here would be to establish a common
infrastucture where various special requirements could easily be implemented
without affecting the core funtionality too much. Your intents seems to be
just a simple use case of the need to extend/override the functionality of
the existing layer data sources which should be handled in a common way.

At that time when this proposal have been created (along with working
patches, see the corresponding ticket) I couldn't gather any community
support to make it realized in the development version. At this time I'm not
too keen to spend more efforts on this, however I would personally support
any effort to implement a concept which could be extensible such way.


Best regards,

Tamas
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