/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
/**
* Defines the interfaces of the JCR SPI (Service Provider Interface).
*
* <p>
* The SPI cuts the JCR stack into two parts:
* <ul>
* <li>Above the SPI an implementation that wishes to expose the JCR API again
* needs to implement the transient item space, the session local namespace
* mapping and various conversions from the value representation in the SPI to
* the resolved values in the JCR API.</li>
* <li>An implementation of the SPI interfaces has to deal with the persistent
* view of a JCR repository. This includes almost all aspects of the JSR 170
* specification, except the previously stated transient space and the session
* local namespace resolution to prefixes.</li>
* </ul>
*
* <h3>Observation</h3>
* Because one of the goals of this SPI is to make it easier to implement a
* remoting layer using various existing protocols, the observation mechanism
* has been design with this goal in mind. Instead of a listener registration
* with a callback for each event bundle, the SPI uses a polling mechanism
* with a timeout: {@link org.apache.jackrabbit.spi.RepositoryService#getEvents
* RepositoryService.getEvents()}. With every call to this method the
* repository is advised to return the events that occurred since the last
* call. As a reference to the last retrieved
* {@link org.apache.jackrabbit.spi.EventBundle} the
* {@link org.apache.jackrabbit.spi.SessionInfo} contains a bundle identifier
* which is automatically updated on each call to
* <code>RepositoryService.getEvents()</code>. While this design allows for
* a polling implementation on top of the SPI it is also well suited for a
* listener based observation implementation on top of the SPI. With only
* little thread synchronization overhead events can be acquired using a
* <code>timeout</code> of {@link java.lang.Long#MAX_VALUE}.
* <p>
* If an SPI implementation does not support observation, the method
* <code>RepositoryService.getEvents()</code> will always throw an
* {@link javax.jcr.UnsupportedRepositoryOperationException}.
*/
@aQute.bnd.annotation.Version("3.0.0")
package org.apache.jackrabbit.spi;