/*
 * $Header: /cvshome/build/org.osgi.service.metatype/src/org/osgi/service/metatype/ObjectClassDefinition.java,v 1.11 2006/06/16 16:31:23 hargrave Exp $
 *
 * Copyright (c) OSGi Alliance (2001, 2006). All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.osgi.service.metatype;

import java.io.IOException;
import java.io.InputStream;

/**
 * Description for the data type information of an objectclass.
 * 
 * @version $Revision: 1.11 $
 */
public interface ObjectClassDefinition {
	/**
	 * Argument for <code>getAttributeDefinitions(int)</code>.
	 * <p>
	 * <code>REQUIRED</code> indicates that only the required definitions are
	 * returned. The value is 1.
	 */
	public static final int	REQUIRED	= 1;
	/**
	 * Argument for <code>getAttributeDefinitions(int)</code>.
	 * <p>
	 * <code>OPTIONAL</code> indicates that only the optional definitions are
	 * returned. The value is 2.
	 */
	public static final int	OPTIONAL	= 2;
	/**
	 * Argument for <code>getAttributeDefinitions(int)</code>.
	 * <p>
	 * <code>ALL</code> indicates that all the definitions are returned. The value
	 * is -1.
	 */
	public static final int	ALL			= 0xFFFFFFFF;

	/**
	 * Return the name of this object class.
	 * 
	 * The name may be localized.
	 * 
	 * @return The name of this object class.
	 */
	public String getName();

	/**
	 * Return the id of this object class.
	 * 
	 * <p>
	 * <code>ObjectDefintion</code> objects share a global namespace in the
	 * registry. They share this aspect with LDAP/X.500 attributes. In these
	 * standards the OSI Object Identifier (OID) is used to uniquely identify
	 * object classes. If such an OID exists, (which can be requested at several
	 * standard organisations and many companies already have a node in the
	 * tree) it can be returned here. Otherwise, a unique id should be returned
	 * which can be a java class name (reverse domain name) or generated with a
	 * GUID algorithm. Note that all LDAP defined object classes already have an
	 * OID associated. It is strongly advised to define the object classes from
	 * existing LDAP schemes which will give the OID for free. Many such schemes
	 * exist ranging from postal addresses to DHCP parameters.
	 * 
	 * @return The id of this object class.
	 */
	public String getID();

	/**
	 * Return a description of this object class.
	 * 
	 * The description may be localized.
	 * 
	 * @return The description of this object class.
	 */
	public String getDescription();

	/**
	 * Return the attribute definitions for this object class.
	 * 
	 * <p>
	 * Return a set of attributes. The filter parameter can distinguish between
	 * <code>ALL</code>,<code>REQUIRED</code> or the <code>OPTIONAL</code>
	 * attributes.
	 * 
	 * @param filter <code>ALL</code>,<code>REQUIRED</code>,<code>OPTIONAL</code>
	 * @return An array of attribute definitions or <code>null</code> if no
	 *         attributes are selected
	 */
	public AttributeDefinition[] getAttributeDefinitions(int filter);

	/**
	 * Return an <code>InputStream</code> object that can be used to create an
	 * icon from.
	 * 
	 * <p>
	 * Indicate the size and return an <code>InputStream</code> object containing
	 * an icon. The returned icon maybe larger or smaller than the indicated
	 * size.
	 * 
	 * <p>
	 * The icon may depend on the localization.
	 * 
	 * @param size Requested size of an icon, e.g. a 16x16 pixels icon then size =
	 *        16
	 * @return An InputStream representing an icon or <code>null</code>
	 * @throws IOException If the <code>InputStream</code> cannot be returned.
	 */
	public InputStream getIcon(int size) throws IOException;
}