core/api/src/main/java/org/apache/polygene/api/service/ServiceReference.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.apache.polygene.api.service;

import org.apache.polygene.api.activation.ActivationEventListenerRegistration;
import org.apache.polygene.api.composite.ModelDescriptor;
import org.apache.polygene.api.identity.Identifiable;
import org.apache.polygene.api.structure.MetaInfoHolder;
import org.apache.polygene.api.type.HasTypes;

/**
 * From a ServiceReference you can access and modify metadata about a service.
 * You can also access the actual service through get(), that can then be invoked.
 */
public interface ServiceReference<T>
    extends HasTypes, ActivationEventListenerRegistration, MetaInfoHolder, Identifiable
{
    /**
     * @return the actual service
     */
    T get();

    /**
     * @return TRUE if the service is active, otherwise return FALSE
     */
    boolean isActive();

    /**
     * @return TRUE if the service is available, otherwise return FALSE
     */
    boolean isAvailable();

    /**
     * @return the ServiceModel of the service referenced by this ServiceReference.
     */
     ModelDescriptor model();
}