001// Copyright 2007, 2008, 2009, 2010 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.annotations;
016
017import static java.lang.annotation.RetentionPolicy.RUNTIME;
018
019import java.lang.annotation.Documented;
020import java.lang.annotation.ElementType;
021import java.lang.annotation.Retention;
022import java.lang.annotation.Target;
023
024/**
025 * Marker annotation used to denote a service that is the primary instance of some common interface. This is often used
026 * when a service is a {@linkplain org.apache.tapestry5.ioc.services.ChainBuilder chain of command} or
027 * {@linkplain org.apache.tapestry5.ioc.services.StrategyBuilder strategy-based} and, therefore, many services will
028 * implement the
029 * same interface.
030 */
031@Target(
032{ ElementType.PARAMETER, ElementType.FIELD, ElementType.METHOD })
033@Retention(RUNTIME)
034@Documented
035@UseWith(AnnotationUseContext.SERVICE)
036public @interface Primary
037{
038
039}