| /* |
| * Copyright (c) OSGi Alliance (2000, 2017). 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; |
| |
| import org.osgi.annotation.versioning.ProviderType; |
| |
| /** |
| * LogReaderService for obtaining logging information. |
| * <p> |
| * Since 1.4, {@link org.osgi.service.log.stream.LogStreamProvider} is the |
| * preferred way to obtain {@link LogEntry} objects. |
| * <p> |
| * The LogReaderService provides two ways to obtain {@link LogEntry} objects: |
| * <ul> |
| * <li>The primary way to retrieve {@link LogEntry} objects is to register a |
| * {@link LogListener} object whose {@link LogListener#logged(LogEntry)} method |
| * will be called for each entry added to the log.</li> |
| * <li>To obtain past {@link LogEntry} objects, the {@link #getLog()} method can |
| * be called which will return an {@code Enumeration} of the {@link LogEntry} |
| * objects in the log.</li> |
| * </ul> |
| * |
| * @ThreadSafe |
| * @author $Id$ |
| */ |
| @ProviderType |
| public interface LogReaderService { |
| /** |
| * Subscribes to {@link LogEntry} objects. |
| * <p> |
| * This method registers a {@link LogListener} object with the Log Reader |
| * Service. The {@link LogListener#logged(LogEntry)} method will be called |
| * for each {@link LogEntry} object placed into the log. |
| * <p> |
| * When a bundle which registers a {@link LogListener} object is stopped or |
| * otherwise releases the Log Reader Service, the Log Reader Service must |
| * remove all of the bundle's listeners. |
| * <p> |
| * If this Log Reader Service's list of listeners already contains a |
| * listener {@code l} such that {@code (l==listener)}, this method does |
| * nothing. |
| * <p> |
| * Since 1.4, {@link org.osgi.service.log.stream.LogStreamProvider} is the |
| * preferred way to obtain {@link LogEntry} objects. |
| * |
| * @param listener A {@link LogListener} object to register; the |
| * {@link LogListener} object is used to receive {@link LogEntry} |
| * objects. |
| */ |
| void addLogListener(LogListener listener); |
| |
| /** |
| * Unsubscribes to {@link LogEntry} objects. |
| * <p> |
| * This method unregisters a {@link LogListener} object from the Log Reader |
| * Service. |
| * <p> |
| * If {@code listener} is not contained in this Log Reader Service's list of |
| * listeners, this method does nothing. |
| * <p> |
| * Since 1.4, {@link org.osgi.service.log.stream.LogStreamProvider} is the |
| * preferred way to obtain {@link LogEntry} objects. |
| * |
| * @param listener A {@link LogListener} object to unregister. |
| */ |
| void removeLogListener(LogListener listener); |
| |
| /** |
| * Returns an {@code Enumeration} of the {@link LogEntry} objects in the |
| * log. |
| * <p> |
| * Each element of the enumeration is a {@link LogEntry} object, ordered |
| * with the most recent entry first. Whether the enumeration is of all |
| * {@link LogEntry} objects since the Log Service was started or some recent |
| * past is implementation-specific. |
| * |
| * @return An {@code Enumeration} of the {@link LogEntry} objects in the |
| * log. |
| */ |
| Enumeration<LogEntry> getLog(); |
| } |