Instance.java

/*
 * Copyright (c) 2012 Data Harmonisation Panel
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     HUMBOLDT EU Integrated Project #030962
 *     Data Harmonisation Panel <http://www.dhpanel.eu>
 */

package eu.esdihumboldt.hale.common.instance.model;

import java.util.List;
import java.util.Set;

import eu.esdihumboldt.hale.common.schema.model.TypeDefinition;
import eu.esdihumboldt.hale.common.schema.model.constraint.type.AugmentedValueFlag;
import eu.esdihumboldt.hale.common.schema.model.constraint.type.Binding;
import eu.esdihumboldt.hale.common.schema.model.constraint.type.HasValueFlag;

/**
 * Represents an instance of a type
 * 
 * @author Simon Templer
 * @partner 01 / Fraunhofer Institute for Computer Graphics Research
 */
public interface Instance extends Group {

	/**
	 * Get the definition of the type associated with the instance
	 * 
	 * @return the instance's type definition
	 */
	@Override
	public TypeDefinition getDefinition();

	/**
	 * Get the instance value.<br>
	 * <br>
	 * The value is only present for certain types where the
	 * {@link HasValueFlag} or {@link AugmentedValueFlag} constraint is enabled.
	 * The {@link Binding} constraint on the type definition defines the binding
	 * of the value.<br>
	 * <br>
	 * <b>NOTE:</b> This is needed for instance for XML elements with text
	 * content and attributes. It may only be a simple value (i.e. no
	 * {@link Group} or {@link Instance}).
	 * 
	 * @return the instance value if it is defined, otherwise <code>null</code>
	 */
	public Object getValue();

	/**
	 * Get the data set the instance is associated to.
	 * 
	 * @return the instance data set, <code>null</code> if not set
	 */
	public DataSet getDataSet();

	/**
	 * Get the metadata the instance my be associated with
	 * 
	 * @param key the key to access a certain metadata
	 * @return A list of objects from the metadata, may be an empty List if the
	 *         key can not be found or there is not metadata associated with the
	 *         Instance
	 */
	public List<Object> getMetaData(String key);

	/**
	 * Get all keys the metadata is associated with
	 * 
	 * @return an Set of String keys, or an empty Set if the data doesn't exist
	 *         or the container is empty, the Set may not be changed
	 */
	public Set<String> getMetaDataNames();

}