001// Copyright 2004, 2005 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.tapestry.engine; 016 017/** 018 * A source for configuration properties. 019 * 020 * @author Howard Lewis Ship 021 * @since 2.3 022 * 023 **/ 024 025public interface IPropertySource 026{ 027 /** 028 * Returns the value for a given property, or null if the 029 * source does not provide a value for the named property. 030 * Implementations of IPropertySource may use delegation 031 * to resolve the value (that is, if one property source returns null, 032 * it may forward the request to another source). 033 * 034 **/ 035 036 public String getPropertyValue(String propertyName); 037}