/*
 * Copyright 2009-2010 LinkedIn, Inc.
 * 
 * Licensed 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 voldemort.server.protocol;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;

import voldemort.VoldemortException;
import voldemort.common.nio.ByteBufferContainer;

/**
 * A request handler that answers client requests in some given format
 * 
 * 
 */
public interface RequestHandler {

    /**
     * Handles the request as determined by the protocol and command provided as
     * input.
     * 
     * @param inputStream
     * @param outputStream
     * 
     * @return StreamRequestHandler if this is the beginning of a streaming
     *         request, null if self-contained
     * 
     * @throws IOException
     */

    public StreamRequestHandler handleRequest(DataInputStream inputStream,
                                              DataOutputStream outputStream)
            throws IOException;

    public StreamRequestHandler handleRequest(DataInputStream inputStream,
                                              DataOutputStream outputStream,
                                              ByteBufferContainer outputContainer)
            throws IOException;

    /**
     * This method is used by non-blocking code to determine if the give buffer
     * represents a complete request. Because the non-blocking code can by
     * definition not just block waiting for more data, it's possible to get
     * partial reads, and this identifies that case.
     * 
     * @param buffer Buffer to check; the buffer is reset to position 0 before
     *        calling this method and the caller must reset it after the call
     *        returns
     * @return True if the buffer holds a complete request, false otherwise
     */

    public boolean isCompleteRequest(ByteBuffer buffer) throws VoldemortException;

}