001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.hivemind.lib;
016    
017    /**
018     * Service interface for a source of beans of a particular type.
019     * Bean instances are retrieved using a <em>locator string</em> which is of the form:
020     * <code><em>name</em>[,<em>initializer</em>]</code>.  That is, an optional initializer is
021     * may be specified, separated by a comma.
022     * 
023     * <p>
024     * Beans may be cached or not.
025     * 
026     * <p>
027     * The <code>hivemind.lib.BeanFactoryBuilder</code> service is used to create services
028     * implementing this interface (driven from a configuration).
029     *
030     * @author Howard Lewis Ship
031     */
032    public interface BeanFactory
033    {
034        /**
035         * Returns true if a bean matching the provided locator has been
036         * defined.
037         * 
038         * @param locator the name or name and initializer
039         * @return true if a bean matching the provided locator has ben defined
040         */
041        public boolean contains(String locator);
042        
043        /**
044         * Gets a bean via its locator (it's name plus, optionally, an initializer).
045         * 
046         * @param locator the name or name and initializer
047         * @return a bean instance
048         * @throws org.apache.hivemind.ApplicationRuntimeException if no bean matching the provided 
049         * name has been defined.
050         */
051        public Object get(String locator);
052    }