Re: [Geoserver-devel] Plug-in Datasource

[<ch...@to...>]

The datasource class definition is basically provided in the 
DatasourceParams element.  The way it works is that a properly 
implemented geotools plug in datasource will provide a datasource 
factory class the implements the service provider interface.  The META-
INF of the jar will have a file pointing to that datasource factory.  
Each of those factories is registered, and then to invoke a geotools 
datasource you just call it with the right params.  This is why we 
switched to the DatasourceParams from the old style of just specifying 
host, user, password, ect.  The DatasourceParams should be the correct 
params to invoke the datasource you want to use.  For postgis this is 
done by having each of the appropriate params (check the 
PostgisDatasourceFactory class for more info on how this done...I don't 
have the link right now, but it's in the postgis geotools module), 
including a dbtype='postgis'.  For shapefiles it checks that there is a 
param named url which has a file ending in .shp.  Geoserver also 
provides a 'filename' param, which will construct a url in the 
featureType directory, so that if you put a road.shp in 
featureTypes/road, then you just need to specify the filename as 
road.shp, and the right url will be passed to the datasource 
factories.  Other file based datasources may look for the appropriate 
file type suffix, or rbdm may also look for a dbtype and the presence 
of the appropriate host, password, user, tablename, ect.  It depends on 
how the implementor decides to do it.  Shapefile is
not currently truly plug-in, as we're rolling the jar ourselves.  But 
it could easily be a seperate jar.  So the thing that you're missing is 
the specification of the appropriate params for each datasource.  As 
people provide new datasources they need to implement the factory and 
then let users know what parameters are needed to invoke the new 
datasource.  Does this make sense?  I'll add some notes to the 
documentation to make this clearer.  I've also been meaning to write 
something for geotools on 'how to implement a new datasource', that 
will explain all the nitty gritty details past 'you just extend 
abstract datasource'.  If anyone is interested in implementing a new 
geotools datasource let me know and I'll motivate to get that out to 
you and up on geotools.

     thanks,

          Chris


Quoting David R Robison <drr...@op...>:

> I noticed that in 0.96 shapefiles are now supported as a "plug-in".
> The
> documentation says that additional data sources may be added by
> using
> the AbstractDataSource class from geotools. One question I have is
> now
> does geoserver know how to instantiate the data source? I would
> expect
> some kind of DataSource class definition in the info.xml file, but I
> don't see it. Am I missing something?
>  
> David R Robison
> Open Roads Consulting, Inc.
> http://www.openroadsconsulting.com
>  
> 




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