/**
 * 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.camel;

/**
 * An <a href="http://activemq.apache.org/camel/expression.html">expression</a>
 * provides a plugin strategy for evaluating expressions on a message exchange to support things like
 * <a href="http://activemq.apache.org/camel/scripting-languages.html">scripting languages</a>,
 * <a href="http://activemq.apache.org/camel/xquery.html">XQuery</a>
 * or <a href="http://activemq.apache.org/camel/sql.html">SQL</a> as well
 * as any arbitrary Java expression.
 *
 *
 * @version $Revision: 303 $
 */
public interface Expression<E extends Exchange> {

    /**
     * Returns the value of the expression on the given exchange
     *
     * @param exchange the message exchange on which to evaluate the expression
     * @return the value of the expression
     */
    Object evaluate(E exchange);
}
