= Exercise =

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You know everything now about writting zcfg matadata files and get short pieces of code in {{{service.c}}} or {{{ogr_service_provider.py}}} depending if you choosen C or Python programming language respectively.

The goal of this exercise is to implement the following multiple geometries services :

 * Intersection
 * Union
 * Difference
 * !SymDifference

== C version ==

Your are now invited to edit the {{{source.c}}} file you have created during this workshop to add the multiple geometries, using the following OGR C-API functions :

 * [http://www.gdal.org/ogr/ogr__api_8h.html#5a271b5c7b72994120e7a6bbc7e7e5cb OGR_G_Intersection](OGRGeometryH, OGRGeometryH)
 * [http://www.gdal.org/ogr/ogr__api_8h.html#f58f2cfbdb2497659d2eabea73d3b8a0 OGR_G_Union](OGRGeometryH, OGRGeometryH)
 * [http://www.gdal.org/ogr/ogr__api_8h.html#497977bec6ecd9dade7a9694f776be64 OGR_G_Difference](OGRGeometryH, OGRGeometryH)
 * [http://www.gdal.org/ogr/ogr__api_8h.html#d6dacf495617a230c6f19950bc415f17 OGR_G_SymmetricDifference](OGRGeometryH, OGRGeometryH)

You can use the {{{Boundary.zcfg}}} file as example, rename the {{{InputPolygon}}} input to {{{InputEntity1}}} and add a similar input named {{{IntputEntity2}}}. You are invited to update other values in the ZOO Metadata File to set the proper metadata informations.

== Python Version ==

Your are invited to edit the {{{ogr_ws_service_provider.py}}} file you created during this workshop to add the multiple geometries using the following {{{osgeo.ogr}}} {{{Geometry}}} methods applied on the first {{{Geometry}}} instance :

 * Intersection(Geometry)
 * Union(Geometry)
 * Difference(Geometry)
 * !SymmetricDifference(Geometry)

You can once again use the {{{Boundary.zcfg}}} file as example, rename the {{{InputPolygon}}} input to {{{InputEntity1}}} and add a similar input named {{{IntputEntity2}}}. You are invited to update other values in the ZOO metadata file to set the proper metadata informations.

== Testing your services ==

Once the multiple geometries Services are deployed on your local environment, please reload the {{{zoo-ogr.html}}} file created during the previous section from your browser and test your brand new ZOO Services.
Once the multiple geometries Services are deployed on your local environment, please reload the zoo-ogr.html created during the previous section from your browser and test your brand new ZOO Services.