org.osgi.service.log.LogReaderService Maven / Gradle / Ivy
/*
* Copyright (c) OSGi Alliance (2000, 2008). 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.log;
import java.util.Enumeration;
/**
* Provides methods to retrieve LogEntry objects from the log.
*
* There are two ways to retrieve LogEntry objects:
*
* - The primary way to retrieve
LogEntry objects is to register a
* LogListener object whose LogListener.logged method will
* be called for each entry added to the log.
* - To retrieve past
LogEntry objects, the getLog
* method can be called which will return an Enumeration of all
* LogEntry objects in the log.
*
* @ThreadSafe
* @version $Revision: 5654 $
* @see LogEntry
* @see LogListener
* @see LogListener#logged(LogEntry)
*/
public interface LogReaderService {
/**
* Subscribes to LogEntry objects.
*
*
* This method registers a LogListener object with the Log Reader
* Service. The LogListener.logged(LogEntry) method will be
* called for each LogEntry object placed into the log.
*
*
* When a bundle which registers a LogListener object is stopped
* or otherwise releases the Log Reader Service, the Log Reader Service must
* remove all of the bundle's listeners.
*
*
* If this Log Reader Service's list of listeners already contains a
* listener l such that (l==listener), this method
* does nothing.
*
* @param listener A LogListener object to register; the
* LogListener object is used to receive LogEntry
* objects.
* @see LogListener
* @see LogEntry
* @see LogListener#logged(LogEntry)
*/
public void addLogListener(LogListener listener);
/**
* Unsubscribes to LogEntry objects.
*
*
* This method unregisters a LogListener object from the Log
* Reader Service.
*
*
* If listener is not contained in this Log Reader Service's list
* of listeners, this method does nothing.
*
* @param listener A LogListener object to unregister.
* @see LogListener
*/
public void removeLogListener(LogListener listener);
/**
* Returns an Enumeration of all LogEntry objects in
* the log.
*
*
* Each element of the enumeration is a LogEntry object, ordered
* with the most recent entry first. Whether the enumeration is of all
* LogEntry objects since the Log Service was started or some
* recent past is implementation-specific. Also implementation-specific is
* whether informational and debug LogEntry objects are included
* in the enumeration.
* @return An Enumeration of all LogEntry objects in
* the log.
*/
public Enumeration getLog();
}