001    // Copyright 2008 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    
015    package org.apache.tapestry5.ioc;
016    
017    /**
018     * For Tapestry IoC, Aspects provide a limited amount of advise, i.e., advising method invocations. That's the only join
019     * point available (method invocations of service interface methods); full AOP systems such as AspectJ can do much, much
020     * more, such as advising field access and even object construction.
021     *
022     * @see org.apache.tapestry5.ioc.services.AspectDecorator
023     */
024    public interface MethodAdvice
025    {
026        /**
027         * Allows the Aspect to advise the invocation.  The Aspect is free to inspect and even replace parameters. Most
028         * Aspects will then invoke {@link org.apache.tapestry5.ioc.Invocation#proceed()}.  The Aspect may then inspect and
029         * replace any checked thrown exceptions. Some Aspects (for example, caching) may selectively decide to bypass the
030         * invocation entirely, and instead invoke some other method or otherwise set a return value or thrown exception.
031         *
032         * @param invocation to advise
033         */
034        void advise(Invocation invocation);
035    }