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/*
* Copyright 2006-2010 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.*;
/**
* A hint for a dependent {@link Repository} to allow a {@link Storable} property or type
* to be undefined in the underlying schema. Ordinarily, if a dependent repository cannot
* find a matching property, it throws {@link MismatchException} when the {@link Storage} is
* first retrieved for the storable. This annotation suppresses that exception, and instead
* makes the property or type unsupported. Any subsequent invocation of a property access
* method for the independent type or property will cause an UnsupportedOperationException
* to be thrown.
*
* <p>One example of when this might be used would be to store a calculated
* field in the cached representation of the object. It is <b>not</b>
* necessary to prevent implemented methods of the form {@literal "get<value>"}
* from being inadvertently interpreted as properties of the storable; any
* implementation is by definition not a property.
*
* <p>If a correctly matching property actually is found, then this annotation
* is ignored and the property or type is defined as usual. If the Repository
* finds a property whose name matches, but whose type does not match, a
* MismatchException will be thrown regardless of this annotation.
*
* <p>Independent repositories completely ignore this annotation.
*
* <p>Example:<pre>
* public interface UserInfo extends Storable<UserInfo> {
* <b>@Independent</b>
* String getName();
* void setName(String name);
*
* ...
* }
* </pre>
*
* <b>Note:</b> If a {@link Version versioned} Storable with an independent
* property is managed by a replicating repository, updates which modify just
* the independent property still update the master Storable, in order to get a
* new record version. Therefore, independent properties should not be used as
* a performance enhancement which avoids writes to a master repository.
*
* @author Brian S O'Neill
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface Independent {
}
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