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}