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    
015    package org.apache.tapestry5.ioc;
016    
017    /**
018     * Allows certain types of lifecycles to control exactly how services are instantiated.
019     */
020    public 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    }