[Mapserver-dev] FeatureID filtering in SLD

[Kralidis,Tom [Burlington]]

> -----Original Message-----
> From: mapserver-dev-admin at lists.gis.umn.edu 
> [mailto:mapserver-dev-admin at lists.gis.umn.edu] On Behalf Of 
> Jeremy Wiebe
> Sent: Tuesday, 03 August, 2004 14:13
> To: 'mapserver-dev at lists.gis.umn.edu'
> Subject: [Mapserver-dev] FeatureID filtering in SLD
> 
> 
> Hi there,
> 
> I am wondering if anybody else sees benefit in implementing 
> the <FeatureId>
> filter from the Filter Encoding Specification.   I've 
> searched back in the
> -dev archives and can only find one reference to this filter 
> type and it wasn't followed up at all.
> 
> A bit of background... our company is using MapServer as a 
> mapping tool with search capabilities (both spatial and 
> tabular).  The search results are highlighted on the map.  
> Currently we use one <Rule> for each matching feature (only 
> one layer has highlighted features).  This ends up with an 
> SLD file that grows quite rapidly as features that match the 
> search grow.  (With about 300 matches you get an SLD file 
> that is over 1 MB).  If we were able to use the <FeatureId 
> fid="WINNIPEG_1M.1234" /> filter the SLD would shrink significantly.  
> 

True.  Can you not also do a FilterExpression with an SQL 'IN' statement
to bunch these all together?

> Now, back to the question, would this be useful to anyone?
>

The question is how to map what a given layer's 'id' def is in
MapServer.
 
> My second question is about implementation of this.  The SLD 
> contains a <NamedLayer> element right below the 
> <StyledLayerDescriptor> element.  The <Rule> and <Filter> 
> elements are nested within this <NamedLayer> element. As far 
> as I understand the Filter Encoding Spec, the layer name is 
> specified within the <FeatureId>'s "fid" attribute as such: 
> <FeatureId fid="MY_LAYER.MY_FEATURE_ID" />
> 
> Should the MapServer only accept layer names in the 
> <FeatureId> element that match the <LayerName> that they are 
> nested in or allow any layer name to be
> specified?   
> 

Should it?  For the Filter spec per se, I would say yes.  When a filter
is bundled with an SLD document, I think it may be redundant
information.  We might want to check with the SLD and Filter folks at
OGC.

..Tom


> Jeremy Wiebe
> Application Developer
> Linnet - The Land Systems Company 
> 1600-444 St. Mary Avenue,  Winnipeg, Manitoba, Canada, R3C 3T1
> Tel: 1-204-957-6452  Fax: 1-204-957-7568  email: 
> jwiebe at linnet.ca http://www.linnet.ca 
> 
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