    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}