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
015package org.apache.hivemind.internal;
016
017/**
018 * A service model is associated with a {@link org.apache.hivemind.internal.ServicePoint} to supply
019 * rules for the lifecycle of the service. This concerns when the service is first created and
020 * whether it is pooled, etc. Each service extension point will have a unique instance of
021 * ServiceModel.
022 * 
023 * @author Howard Lewis Ship
024 */
025public interface ServiceModel
026{
027    /**
028     * Invoked by the service extension point to obtain the service implementation. The model may
029     * return the actual service implementation or some form of proxy.
030     * <p>
031     * This method is only invoked <em>once</em>; the returned value is used from that point on
032     * (in all threads, by all callers). Most models return a proxy that takes care of realizing the
033     * service (actually creating the service, configuring it, and wrapping it with interceptors)
034     * only when needed.
035     */
036
037    public Object getService();
038
039    /**
040     * Forces the core service implementation (and any interceptors) to be fully instantiated
041     * immediately, rather than waiting for the first service method invocation. This is used when a
042     * service needs to be "eagerly loaded" rather than "lazy loaded".
043     */
044    public void instantiateService();
045}