001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.camel; 018 019/** 020 * Used for defining if a given class is singleton or not. If the class is a singleton, 021 * then a single instance will be shared (and hence should be treated as immutable and 022 * be used in a thread-safe manner). 023 * <p/> 024 * This interface is not implemented as a marker interface (i.e., it's necessary to read 025 * {@link #isSingleton()} instead of <tt>instanceof(IsSingleton))</tt>. 026 * This allows for subclasses to have a singleton status different from a parent and 027 * for objects to have this value dynamically changed. 028 * <p/> 029 * Camel component are very often singleton based, only a few components are not. 030 */ 031public interface IsSingleton { 032 033 /** 034 * Whether this class supports being singleton or not. 035 * 036 * @return <tt>true</tt> to be a single shared instance, <tt>false</tt> to create new instances. 037 */ 038 boolean isSingleton(); 039 040}