This page represents the current plan; for discussion please check the tracker link above.

Description

This proposal:

• introduces DataAccess as a super class of DataStore
• traditional DataStore methods are maintained; often type narrowing a method in DataAccess
• client code can be written against DataAccess for the general case; DataStore offers more specific that can make use of the SimpleFeature assumption
• this proposal covers a naming convention / design stratagy that can be used for GridAccess as well

Additional information:

Status

Voting took place at today's IRC meeting over the approach #1(Generics + DataStore superclass), see Dry Run at DataAccess+Story for a summary.

• Andrea Aime 0
• Ian Turton
• Justin Deoliveira +1
• Jody Garnett +1
• Martin Desruisseaux +1
• Simone Giannecchini +1

Tasks

1. Introduce DataAccess level classes
2. Allow DataStore level classes to extend; patching up implementations as needed
3. Update and test GeoServer
4. Update and test uDig (and axios community edit tools)
5. Update the user guide

API Changes

The API changes needed are minimal and respect the current interfaces and behaviour. The general strategy is to pull up the common methods from DataStore to a superclass and parametrize as per the Feature and FeatureType flavor they use.

BEFORE

/** @since 2.0 */
interface DataStore{
   void createSchema(SimpleFeatureType featureType);
   SimpleFeatureType getSchema(String typeName) throws IOException;
   FeatureSource getFeatureSource(String typeName);
   ...
}

AFTER

/** @since 2.5 */
interface DataAccess<T extends FeatureType, F extends Feature>{
    List<Name> getNames();
    void createSchema(T featureType);
    T getSchema(Name name);
    FeatureSource<T,F> getFeatureSource(Name typeName);
    ....
}
/** @since 2.0 */
interface DataStore extends DataAccess<SimpleFeatureType, SimpleFeature>{
   void createSchema(SimpleFeatureType featureType);
   /** @since 2.0 */
   SimpleFeatureType getSchema(String typeName) throws IOException;
   /** @since 2.5 */
   SimpleFeatureType getSchema(Name typeName) throws IOException;
   FeatureSource<SimpleFeatureType,SimpleFeature> getFeatureSource(String typeName);
   ...
}

BEFORE

/** @since 2.0 */
public interface FeatureSource {
   FeatureCollection getFeatures(Query query);
   SimpleFeatureType getSchema();
   DataStore getDataStore();
}

AFTER

/** @since 2.0 */
public interface FeatureSource<T extends FeatureType, F extends Feature> {
   FeatureCollection<T,F> getFeatures(Query query);
   T getSchema();
   DataAccess<T, F> getDataStore();
}

Documentation Changes

• Developers Guide will need a section on adding a DataAccess api that has the right feel
• Data Module from the Module matrix page
• Upgrade to 2.5
• http://svn.geotools.org/geotools/trunk/gt/demo/example/
• Home
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