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/*
* Copyright (c) OSGi Alliance (2004, 2013). All Rights Reserved.
*
* 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.osgi.service.dmt;
/**
* Event class storing the details of a change in the tree. {@code DmtEvent} is
* used by {@code DmtAdmin} to notify registered {@link DmtEventListener
* EventListeners} services about important changes. Events are generated after
* every successful DMT change, and also when sessions are opened or closed. If
* a {@link DmtSession} is opened in atomic mode, DMT events are only sent when
* the session is committed, when the changes are actually performed.
*
* The {@code type} of the event describes the change that triggered the event
* delivery. Each event carries the unique identifier of the session in which
* the described change happened or -1 when the change originated outside a
* session. The events describing changes in the DMT carry the list of affected
* nodes. In case of {@link #COPIED} or {@link #RENAMED} events, the event
* carries the list of new nodes as well.
*
* @author $Id: 6ca0dc54a7e040668d4f97d158cd6799adbe3571 $
*/
public interface DmtEvent {
/**
* Event type indicating nodes that were added.
*/
int ADDED = 0x01;
/**
* Event type indicating nodes that were copied.
*/
int COPIED = 0x02;
/**
* Event type indicating nodes that were deleted.
*/
int DELETED = 0x04;
/**
* Event type indicating nodes that were renamed.
*/
int RENAMED = 0x08;
/**
* Event type indicating nodes that were replaced.
*/
int REPLACED = 0x10;
/**
* Event type indicating that a new session was opened.
*/
int SESSION_OPENED = 0x20;
/**
* Event type indicating that a session was closed. This type of event is
* sent when the session is closed by the client or becomes inactive for any
* other reason (session timeout, fatal errors in business methods, etc.).
*/
int SESSION_CLOSED = 0x40;
/**
* This method returns the type of this event.
*
* @return the type of this event.
*/
int getType();
/**
* This method returns the identifier of the session in which this event
* took place. The ID is guaranteed to be unique on a machine.
*
* For events that do not result from a session, the session id is -1.
*
* The availability of a session.id can also be check by using
* {@code getProperty()} with "session.id" as key.
*
* @return the unique identifier of the session that triggered the event or
* -1 if there is no session associated
*/
int getSessionId();
/**
* This method can be used to query the subject nodes of this event. The
* method returns {@code null} for {@link #SESSION_OPENED} and
* {@link #SESSION_CLOSED}.
*
* The method returns only those affected nodes that the caller has the GET
* permission for (or in case of {@link #COPIED} or {@link #RENAMED} events,
* where the caller has GET permissions for either the source or the
* destination nodes). Therefore, it is possible that the method returns an
* empty array. All returned URIs are absolute.
*
* @return the array of affected nodes
* @see #getNewNodes()
*/
String[] getNodes();
/**
* This method can be used to query the new nodes, when the type of the
* event is {@link #COPIED} or {@link #RENAMED}. For all other event types
* this method returns {@code null}.
*
* The array returned by this method runs parallel to the array returned by
* {@link #getNodes()}, the elements in the two arrays contain the source
* and destination URIs for the renamed or copied nodes in the same order.
* All returned URIs are absolute.
*
* This method returns only those nodes where the caller has the GET
* permission for the source or destination node of the operation.
* Therefore, it is possible that the method returns an empty array.
*
* @return the array of newly created nodes
*/
String[] getNewNodes();
/**
* This method can be used to query the names of all properties of this
* event.
*
* The returned names can be used as key value in subsequent calls to
* {@link #getProperty(String)}.
*
* @return the array of property names
* @see #getProperty(String)
* @since 2.0
*/
String[] getPropertyNames();
/**
* This method can be used to get the value of a single event property.
*
* @param key the name of the requested property
* @return the requested property value or null, if the key is not contained
* in the properties
* @see #getPropertyNames()
* @since 2.0
*/
Object getProperty(String key);
}