/* * Copyright 2006-2012 Amazon Technologies, Inc. or its affiliates. * Amazon, Amazon.com and Carbonado are trademarks or registered trademarks * of Amazon Technologies, Inc. or its affiliates. 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 com.amazon.carbonado; import java.lang.annotation.*; /** * Designates a {@link Storable} property as being the authoritative version * number for the entire Storable instance. Only one property can have this * designation. * *

Philosophically, a version property can be considered part of the * identity of the storable. Unless the version is {@link Derived}, the * repository is responsible for establishing the version on insert, and for * auto-incrementing it on update. Under no circumstances should a normal * version property be incremented manually; this can result in a false {@link * OptimisticLockException}, or worse may allow the persistent record to become * corrupted. * *

When updating a storable which has a normal version property, a value for * the version must be specified along with its primary key. Otherwise, an * {@link IllegalStateException} is thrown when calling update. If the update * operation detects that the specified version doesn't exactly match the * version of the existing persisted storable, an {@link * OptimisticLockException} is thrown. For {@link Derived} versions, an {@link * OptimisticLockException} is thrown only if the update detects that the new * version hasn't incremented. * *

The actual type of the version property can be anything, but some * repositories might only support integers. For maximum portability, version * properties should be a regular 32-bit int. * *

Example:

 * public interface UserInfo extends Storable {
 *     @Version
 *     int getRecordVersionNumber();
 *     void setRecordVersionNumber(int version);
 *
 *     ...
 * }
 * 
* * @author Brian S O'Neill * @author Don Schneider * @see OptimisticLockException */ @Documented @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.METHOD}) public @interface Version { }