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}