/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.chain;
import java.util.Map;
/**
* <p>A {@link Context} represents the state information that is
* accessed and manipulated by the execution of a {@link Command} or a
* {@link Chain}. Specialized implementations of {@link Context} will
* typically add JavaBeans properties that contain typesafe accessors
* to information that is relevant to a particular use case for this
* context, and/or add operations that affect the state information
* that is saved in the context.</p>
*
* <p>Implementations of {@link Context} must also implement all of the
* required and optional contracts of the <code>java.util.Map</code>
* interface.</p>
*
* <p>It is strongly recommended, but not required, that JavaBeans
* properties added to a particular {@link Context} implementation exhibit
* <em>Attribute-Property Transparency</em>. In other words,
* a value stored via a call to <code>setFoo(value)</code> should be visible
* by calling <code>get("foo")</code>, and a value stored
* via a call to <code>put("foo", value)</code> should be
* visible by calling <code>getFoo()</code>. If your {@link Context}
* implementation class exhibits this featue, it becomes easier to reuse the
* implementation in multiple environments, without the need to cast to a
* particular implementation class in order to access the property getter
* and setter methods.</p>
*
* <p>To protect applications from evolution of this interface, specialized
* implementations of {@link Context} should generally be created by extending
* the provided base class ({@link org.apache.commons.chain.impl.ContextBase})
* rather than directly implementing this interface.</p>
*
* <p>Applications should <strong>NOT</strong> assume that
* {@link Context} implementations, or the values stored in its
* attributes, may be accessed from multiple threads
* simultaneously unless this is explicitly documented for a particular
* implementation.</p>
*
* @author Craig R. McClanahan
* @version $Revision: 480477 $ $Date: 2006-11-29 08:34:52 +0000 (Wed, 29 Nov 2006) $
*/
public interface Context extends Map {
}