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The main module contains the GeoTools public interfaces that are used by other GeoTools modules (and GeoTools applications). Where possible we make use industry standard terms as provided by OGC and ISO standards. The formal GeoTools public api consists of gt-metadata, jts and the gt-main module. The main module contains the default implementations that are available provided to other GeoTools modules using our factory system. Factories are obtained from an appropriate FactoryFinder, giving applications a chance configure the factory used using the Factory Hints facilities. FilterFactory ff = CommonFactoryFinder.getFilterFactory(); Expression expr = ff.add( expression1, expression2 ); If you find yourself using implementation specific classes chances are you doing it wrong: Expression expr = new AddImpl( expression1, expressiom2 );

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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2008, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 */
package org.geotools.data;

import java.io.IOException;
import java.util.Map;

/**
 * Factory used to construct a DataStore from a set of parameters.
 *
 * The following example shows how a user might connect to a PostGIS database, and maintain the
 * resulting DataStore in a Registry:
 *
 * 

 *
 * 

 * HashMap params = new HashMap();
 * params.put("namespace", "leeds");
 * params.put("dbtype", "postgis");
 * params.put("host","feathers.leeds.ac.uk");
 * params.put("port", "5432");
 * params.put("database","postgis_test");
 * params.put("user","postgis_ro");
 * params.put("passwd","postgis_ro");
 *
 * DefaultRegistry registry = new DefaultRegistry();
 * registry.addDataStore("leeds", params);
 *
 * DataStore postgis = registry.getDataStore( "leeds" );
 * SimpleFeatureSource = postgis.getFeatureSource( "table" );
 * 
 *
 * Implementation Notes
 *
 * An instance of this interface should exist for all data stores which want to take advantage of
 * the dynamic plug-in system. In addition to implementing this factory interface each DataStore
 * implementation should have a services file:
 *
 * 
META-INF/services/org.geotools.data.DataStoreFactorySpi
 *
 * 
The file should contain a single line which gives the full name of the implementing class.
 *
 * 
example:

 * e.g.
 * org.geotools.data.mytype.MyTypeDataSourceFacotry
 *
 * 
The factories are never called directly by client code, instead the DataStoreFinder class is
 * used.
 *
 * @author Jody Garnett, Refractions Research
 */
public interface DataStoreFactorySpi extends DataAccessFactory {
    /**
     * Construct a live data source using the params specifed.
     *
     * 
You can think of this as setting up a connection to the back end data source.
     *
     * 
Magic Params: the following params are magic and are honoured by convention by the
     * GeoServer and uDig application.
     *
     * 

     *   "user": is taken to be the user name
     *   
"passwd": is taken to be the password
     *   
"namespace": is taken to be the namespace prefix (and will be kept in sync with
     *       GeoServer namespace management.
     * 
     *
     * When we eventually move over to the use of OpperationalParam we will have to find someway to
     * codify this convention.
     *
     * @param params The full set of information needed to construct a live data store. Typical key
     *     values for the map include: url - location of a resource, used by file reading
     *     datasources. dbtype - the type of the database to connect to, e.g. postgis, mysql
     * @return The created DataStore, this may be null if the required resource was not found or if
     *     insufficent parameters were given. Note that canProcess() should have returned false if
     *     the problem is to do with insuficent parameters.
     * @throws IOException if there were any problems setting up (creating or connecting) the
     *     datasource.
     */
    DataStore createDataStore(Map params) throws IOException;

    //    /**
    //     * Construct a simple MetadataEntity providing internationlization information
    //     * for the data source that *would* be created by createDataStore.
    //     * 
    //     * Suitable for use by CatalogEntry, unknown if this will make
    //     * a DataStore behind the scenes or not. It is possible it will
    //     * communicate with the data source though (hense the IOException).
    //     * 
    //     * @param params The full set of information needed to construct a live
    //     *        data store
    //     * @return MetadataEntity with descriptive information (including
    //     *         internationlization support).
    //     */
    //    DataSourceMetadataEnity createMetadata( Map params ) throws IOException;
    DataStore createNewDataStore(Map params) throws IOException;
}