001    /*
002     * Copyright 2006 Stephen J. McConnell.
003     *
004     * Licensed  under the  Apache License,  Version 2.0  (the "License");
005     * you may not use  this file  except in  compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     *   http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed  under the  License is distributed on an "AS IS" BASIS,
012     * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
013     * implied.
014     *
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package net.dpml.runtime;
020    
021    import net.dpml.state.State;
022    import net.dpml.state.StateListener;
023    
024    /**
025     * Component interface.
026     *
027     * @author <a href="http://www.dpml.net">Digital Product Management Library</a>
028     * @version 2.1.1
029     */
030    public interface Provider
031    {
032       /**
033        * Add a state change listener to the state machine.
034        * @param listener the state listener
035        */
036        void addStateListener( final StateListener listener );
037        
038       /**
039        * Remove a state listener from the state machine.
040        * @param listener the state listener
041        */
042        void removeStateListener( final StateListener listener );
043        
044       /**
045        * Return the current state of the instance.
046        * @return the current state
047        */
048        State getState();
049    
050       /**
051        * Return a fully commissioned instance.
052        * @param type the instance return type
053        * @return the instance
054        */
055        <T>T getInstance( Class<T> type );
056        
057    }
058