/*
 * Negotiation.java February 2007
 *
 * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
 *
 * 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 org.simpleframework.transport;

import java.io.IOException;

/**
 * The <code>Negotiation</code> interface is used to represent an SSL
 * negotiation. When an operation can not be completed this will allow a task to
 * perform asynchronous operations and resume the negotiation when those
 * operations can be fulfilled.
 * 
 * @author Niall Gallagher
 */
interface Negotiation extends Notifier {

    /**
     * This is used to resume the negotiation when an operation has completed.
     * This will continue the decrypt and encrypt sequence of messages required
     * to fulfill the negotiation.
     */
    void resume() throws IOException;

    /**
     * This method is invoked when the negotiation is done and the next phase of
     * the connection is to take place. This will typically be invoked when an
     * SSL handshake or termination exchange has completed successfully.
     */
    void commit() throws IOException;

    /**
     * This is used to send any messages the negotiation may have. If the
     * negotiation can not send the information during its execution then this
     * method will be executed when a select operation is signaled.
     * 
     * @return this returns true when the message has been sent
     */
    boolean send() throws IOException;

    /**
     * This is used to receive data from the client. If at any point during the
     * negotiation a message is required that can not be read immediately this
     * is used to asynchronously read the data when a select operation is
     * signaled.
     * 
     * @return this returns true when the message has been read
     */
    boolean receive() throws IOException;
}