[fdo-internals] New RFC10 Is Posted

[Orest Halustchak]

Overrides are meant to be used for things that are very specific to the
provider and are not generic FDO capabilities, e.g. things related to
physical configuration.

Orest.

-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Traian
Stanev
Sent: Tuesday, September 11, 2007 10:48 AM
To: FDO Internals Mail List
Subject: RE: [fdo-internals] New RFC10 Is Posted

> I stand corrected!  I presume these overrides are rarely used, is that
right?
> As far as I can tell most things that can be manipulated via these
custom
> provider apis (overrides I guess...) can also be controlled using the
> generic APIs and configuration xml for the GDAL provider.  Is that
generally
> the case?  That the override apis are roughly speaking APIs to set and
> manipulate the stuff you could set in the configuration file?

I don't know, I have never personally used overrides :). My (limited)
knowledge of overrides is that they provide access to information that
is specific to the underlying physical data store. This is in addition
to things like capabilities, and connection properties, which also
define provider specific stuff... It is possible to write a provider
without overrides -- the OGR provider and the SDF provider for example
don't have any, although SDF does have extra headers to expose the
scrollable feature reader -- which is somewhat of an override.

Traian



-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org
[mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Frank
Warmerdam (External)
Sent: Tuesday, September 11, 2007 10:37 AM
To: FDO Internals Mail List
Subject: Re: [fdo-internals] New RFC10 Is Posted

Traian Stanev wrote:
>> This is clearly an aspect of FDO I don't understand.  I do not
> understand
>> what override apis are or how it is possible to call custom c++
> methods
>> from a particular provider when we don't even install include files
> for
>> them (to the best of my knowledge).  I guess this "provider specific
>> APIs" stuff is seems foreign to me because I have always tried hard
>> to avoid it in GDAL/OGR.
> 
> Hi Frank, 
> 
> The WMS override headers are there together with the FDO header, so in
> theory they are there. However, I do agree with you that having API
> specific to providers goes against the abstraction that is FDO. It
makes
> the client code have to special case providers, which automatically
> reduces the value of the FDO API abstraction.


Traian,

I stand corrected!  I presume these overrides are rarely used, is that
right?
As far as I can tell most things that can be manipulated via these
custom
provider apis (overrides I guess...) can also be controlled using the
generic APIs and configuration xml for the GDAL provider.  Is that
generally
the case?  That the override apis are roughly speaking APIs to set and
manipulate the stuff you could set in the configuration file?

Best regards,
-- 
---------------------------------------+--------------------------------
------
I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo,
http://osgeo.org

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