/*
 * Copyright 2002-2007 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package javax.management.remote;

import java.io.Closeable;
import java.io.IOException;
import java.util.Map;
import javax.management.ListenerNotFoundException;
import javax.management.MBeanServerConnection;
import javax.management.NotificationFilter;
import javax.management.NotificationListener;
import javax.security.auth.Subject;

/**
 * <p>The client end of a JMX API connector.  An object of this type can
 * be used to establish a connection to a connector server.</p>
 *
 * <p>A newly-created object of this type is unconnected.  Its {@link
 * #connect connect} method must be called before it can be used.
 * However, objects created by {@link
 * JMXConnectorFactory#connect(JMXServiceURL, Map)
 * JMXConnectorFactory.connect} are already connected.</p>
 *
 * @since 1.5
 */
public interface JMXConnector extends Closeable {
    /**
      * <p>Name of the attribute that specifies the credentials to send
      * to the connector server during connection.  The value
      * associated with this attribute, if any, is a serializable
      * object of an appropriate type for the server's {@link
      * JMXAuthenticator}.
      */
     public static final String CREDENTIALS =
         "jmx.remote.credentials";

     /**
      * <p>Name of the attribute that specifies whether to use the
      * {@linkplain javax.management.event Event Service} to handle
      * notifications for this connector.  The value associated with
      * this attribute, if any, is a String, which must be equal,
      * ignoring case, to {@code "true"} or {@code "false"}.</p>
      *
      * <p>Not all connectors will understand this attribute, but the
      * standard {@linkplain javax.management.remote.rmi.RMIConnector
      * RMI Connector} does.</p>
      *
      * <p>If this attribute is not present, then the system property of the
      * same name (<code>{@value}</code>) is consulted. If that is not set
      * either, then the Event Service is not used.</p>
      *
      * @since 1.7
      */
     public static final String USE_EVENT_SERVICE =
         "jmx.remote.use.event.service";

    /**
     * <p>Establishes the connection to the connector server.  This
     * method is equivalent to {@link #connect(Map)
     * connect(null)}.</p>
     *
     * @exception IOException if the connection could not be made
     * because of a communication problem.
     *
     * @exception SecurityException if the connection could not be
     * made for security reasons.
     */
    public void connect() throws IOException;

    /**
     * <p>Establishes the connection to the connector server.</p>
     *
     * <p>If <code>connect</code> has already been called successfully
     * on this object, calling it again has no effect.  If, however,
     * {@link #close} was called after <code>connect</code>, the new
     * <code>connect</code> will throw an <code>IOException</code>.<p>
     *
     * <p>Otherwise, either <code>connect</code> has never been called
     * on this object, or it has been called but produced an
     * exception.  Then calling <code>connect</code> will attempt to
     * establish a connection to the connector server.</p>
     *
     * @param env the properties of the connection.  Properties in
     * this map override properties in the map specified when the
     * <code>JMXConnector</code> was created, if any.  This parameter
     * can be null, which is equivalent to an empty map.
     *
     * @exception IOException if the connection could not be made
     * because of a communication problem.
     *
     * @exception SecurityException if the connection could not be
     * made for security reasons.
     */
    public void connect(Map<String,?> env) throws IOException;

    /**
     * <p>Returns an <code>MBeanServerConnection</code> object
     * representing a remote MBean server.  For a given
     * <code>JMXConnector</code>, two successful calls to this method
     * will usually return the same <code>MBeanServerConnection</code>
     * object, though this is not required.</p>
     *
     * <p>For each method in the returned
     * <code>MBeanServerConnection</code>, calling the method causes
     * the corresponding method to be called in the remote MBean
     * server.  The value returned by the MBean server method is the
     * value returned to the client.  If the MBean server method
     * produces an <code>Exception</code>, the same
     * <code>Exception</code> is seen by the client.  If the MBean
     * server method, or the attempt to call it, produces an
     * <code>Error</code>, the <code>Error</code> is wrapped in a
     * {@link JMXServerErrorException}, which is seen by the
     * client.</p>
     *
     * <p>Calling this method is equivalent to calling
     * {@link #getMBeanServerConnection(Subject) getMBeanServerConnection(null)}
     * meaning that no delegation subject is specified and that all the
     * operations called on the <code>MBeanServerConnection</code> must
     * use the authenticated subject, if any.</p>
     *
     * @return an object that implements the
     * <code>MBeanServerConnection</code> interface by forwarding its
     * methods to the remote MBean server.
     *
     * @exception IOException if a valid
     * <code>MBeanServerConnection</code> cannot be created, for
     * instance because the connection to the remote MBean server has
     * not yet been established (with the {@link #connect(Map)
     * connect} method), or it has been closed, or it has broken.
     */
    public MBeanServerConnection getMBeanServerConnection()
            throws IOException;

    /**
     * <p>Returns an <code>MBeanServerConnection</code> object representing
     * a remote MBean server on which operations are performed on behalf of
     * the supplied delegation subject. For a given <code>JMXConnector</code>
     * and <code>Subject</code>, two successful calls to this method will
     * usually return the same <code>MBeanServerConnection</code> object,
     * though this is not required.</p>
     *
     * <p>For each method in the returned
     * <code>MBeanServerConnection</code>, calling the method causes
     * the corresponding method to be called in the remote MBean
     * server on behalf of the given delegation subject instead of the
     * authenticated subject. The value returned by the MBean server
     * method is the value returned to the client. If the MBean server
     * method produces an <code>Exception</code>, the same
     * <code>Exception</code> is seen by the client. If the MBean
     * server method, or the attempt to call it, produces an
     * <code>Error</code>, the <code>Error</code> is wrapped in a
     * {@link JMXServerErrorException}, which is seen by the
     * client.</p>
     *
     * @param delegationSubject the <code>Subject</code> on behalf of
     * which requests will be performed.  Can be null, in which case
     * requests will be performed on behalf of the authenticated
     * Subject, if any.
     *
     * @return an object that implements the <code>MBeanServerConnection</code>
     * interface by forwarding its methods to the remote MBean server on behalf
     * of a given delegation subject.
     *
     * @exception IOException if a valid <code>MBeanServerConnection</code>
     * cannot be created, for instance because the connection to the remote
     * MBean server has not yet been established (with the {@link #connect(Map)
     * connect} method), or it has been closed, or it has broken.
     */
    public MBeanServerConnection getMBeanServerConnection(
                                               Subject delegationSubject)
            throws IOException;

    /**
     * <p>Closes the client connection to its server.  Any ongoing or new
     * request using the MBeanServerConnection returned by {@link
     * #getMBeanServerConnection()} will get an
     * <code>IOException</code>.</p>
     *
     * <p>If <code>close</code> has already been called successfully
     * on this object, calling it again has no effect.  If
     * <code>close</code> has never been called, or if it was called
     * but produced an exception, an attempt will be made to close the
     * connection.  This attempt can succeed, in which case
     * <code>close</code> will return normally, or it can generate an
     * exception.</p>
     *
     * <p>Closing a connection is a potentially slow operation.  For
     * example, if the server has crashed, the close operation might
     * have to wait for a network protocol timeout.  Callers that do
     * not want to block in a close operation should do it in a
     * separate thread.</p>
     *
     * @exception IOException if the connection cannot be closed
     * cleanly.  If this exception is thrown, it is not known whether
     * the server end of the connection has been cleanly closed.
     */
    public void close() throws IOException;

    /**
     * <p>Adds a listener to be informed of changes in connection
     * status.  The listener will receive notifications of type {@link
     * JMXConnectionNotification}.  An implementation can send other
     * types of notifications too.</p>
     *
     * <p>Any number of listeners can be added with this method.  The
     * same listener can be added more than once with the same or
     * different values for the filter and handback.  There is no
     * special treatment of a duplicate entry.  For example, if a
     * listener is registered twice with no filter, then its
     * <code>handleNotification</code> method will be called twice for
     * each notification.</p>
     *
     * @param listener a listener to receive connection status
     * notifications.
     * @param filter a filter to select which notifications are to be
     * delivered to the listener, or null if all notifications are to
     * be delivered.
     * @param handback an object to be given to the listener along
     * with each notification.  Can be null.
     *
     * @exception NullPointerException if <code>listener</code> is
     * null.
     *
     * @see #removeConnectionNotificationListener
     * @see javax.management.NotificationBroadcaster#addNotificationListener
     */
    public void
        addConnectionNotificationListener(NotificationListener listener,
                                          NotificationFilter filter,
                                          Object handback);

    /**
     * <p>Removes a listener from the list to be informed of changes
     * in status.  The listener must previously have been added.  If
     * there is more than one matching listener, all are removed.</p>
     *
     * @param listener a listener to receive connection status
     * notifications.
     *
     * @exception NullPointerException if <code>listener</code> is
     * null.
     *
     * @exception ListenerNotFoundException if the listener is not
     * registered with this <code>JMXConnector</code>.
     *
     * @see #removeConnectionNotificationListener(NotificationListener,
     * NotificationFilter, Object)
     * @see #addConnectionNotificationListener
     * @see javax.management.NotificationEmitter#removeNotificationListener
     */
    public void
        removeConnectionNotificationListener(NotificationListener listener)
            throws ListenerNotFoundException;

    /**
     * <p>Removes a listener from the list to be informed of changes
     * in status.  The listener must previously have been added with
     * the same three parameters.  If there is more than one matching
     * listener, only one is removed.</p>
     *
     * @param l a listener to receive connection status notifications.
     * @param f a filter to select which notifications are to be
     * delivered to the listener.  Can be null.
     * @param handback an object to be given to the listener along
     * with each notification.  Can be null.
     *
     * @exception ListenerNotFoundException if the listener is not
     * registered with this <code>JMXConnector</code>, or is not
     * registered with the given filter and handback.
     *
     * @see #removeConnectionNotificationListener(NotificationListener)
     * @see #addConnectionNotificationListener
     * @see javax.management.NotificationEmitter#removeNotificationListener
     */
    public void removeConnectionNotificationListener(NotificationListener l,
                                                     NotificationFilter f,
                                                     Object handback)
            throws ListenerNotFoundException;

    /**
     * <p>Gets this connection's ID from the connector server.  For a
     * given connector server, every connection will have a unique id
     * which does not change during the lifetime of the
     * connection.</p>
     *
     * @return the unique ID of this connection.  This is the same as
     * the ID that the connector server includes in its {@link
     * JMXConnectionNotification}s.  The {@link
     * javax.management.remote package description} describes the
     * conventions for connection IDs.
     *
     * @exception IOException if the connection ID cannot be obtained,
     * for instance because the connection is closed or broken.
     */
    public String getConnectionId() throws IOException;
}