001// Copyright 2006, 2008 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.tapestry5.ioc;
016
017/**
018 * Allows certain types of lifecycles to control exactly how services are instantiated.
019 */
020public interface ServiceLifecycle
021{
022    /**
023     * Returns the same creator, or a new one, that encapsulates the creation of the core service implementation.
024     *
025     * @param resources source of information about the service to be created, and source of additional services or
026     *                  other resources that may be needed when constructing the core service implementation
027     * @param creator   object capable of creating the service implementation on demand. This is a wrapper around the
028     *                  service's builder method.
029     * @return the service or equivalent service proxy
030     */
031    Object createService(ServiceResources resources, ObjectCreator creator);
032
033    /**
034     * Returns true if the lifecycle is a singleton (a service that will only be created once).  Return false if the
035     * underlying service instance may be created multiple times (for example, the {@link
036     * org.apache.tapestry5.ioc.ScopeConstants#PERTHREAD} scope}. A future version of Tapestry IoC may optimize for the
037     * later case.
038     *
039     * @return true for singletons, false   for services that can be repeatedly constructed
040     */
041    boolean isSingleton();
042}