framework/cayenne-jdk1.5-unpublished/src/main/java/org/apache/cayenne/DataChannelFilter.java

/*****************************************************************
 *   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.cayenne;

import org.apache.cayenne.graph.GraphDiff;
import org.apache.cayenne.query.Query;

/**
 * An interface of a filter that allows to intercept DataChannel operations. Filters allow
 * to implement chains of custom processors around a DataChannel, that can be used for
 * security, monitoring, business logic, providing context to lifecycle event listeners,
 * etc.
 * 
 * @since 3.1
 */
public interface DataChannelFilter {
    
    void init(DataChannel channel);

    QueryResponse onQuery(
            ObjectContext originatingContext,
            Query query,
            DataChannelFilterChain filterChain);

    GraphDiff onSync(
            ObjectContext originatingContext,
            GraphDiff changes,
            int syncType,
            DataChannelFilterChain filterChain);
}