001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel;
018
019/**
020 * An <a href="http://camel.apache.org/expression.html">expression</a>
021 * provides a plugin strategy for evaluating expressions on a message exchange to support things like
022 * <a href="http://camel.apache.org/scripting-languages.html">scripting languages</a>,
023 * <a href="http://camel.apache.org/xquery.html">XQuery</a>
024 * or <a href="http://camel.apache.org/sql.html">SQL</a> as well
025 * as any arbitrary Java expression.
026 *
027 * @version 
028 */
029public interface Expression {
030
031    /**
032     * Returns the value of the expression on the given exchange
033     *
034     * @param exchange the message exchange on which to evaluate the expression
035     * @param type the expected type of the evaluation result
036     * @return the value of the expression
037     */
038    <T> T evaluate(Exchange exchange, Class<T> type);
039}