/**
* 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.
*/
package org.apache.lucene.gdata.server.registry;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
/**
* The {@link Component} annotation is used to annotate a class as a
* server-component of the GDATA-Server. Annotated class can be configured via
* the gdata-config.xml file to be looked up by aribaty classes at runtime via
* the
* {@link org.apache.lucene.gdata.server.registry.GDataServerRegistry#lookup(Class, ComponentType)}
* method.
* <p>
* Classes annotated with the Component annotation need to provide a default
* constructor to be instanciated via reflection. Components of the GData-Server
* are definded in the
* {@link org.apache.lucene.gdata.server.registry.ComponentType} enumeration.
* Each of the enum types are annotated with a
* {@link org.apache.lucene.gdata.server.registry.SuperType} annotation. This
* annotation specifies the super class or interface of the component. A class
* annotated with the Component annotation must implement or extends this
* defined super-type. This enables developers to use custom implemetations of
* the component like a custom {@link org.apache.lucene.gdata.storage.Storage}.
* </p>
* <p>
* Each ComponentType can only registerd once as the
* {@link org.apache.lucene.gdata.server.registry.GDataServerRegistry} does not
* provide multipe instances of a ComponentType.
* </p>
* <p>
* This annotation can only annotate types and can be accessed at runtime.
* {@link java.lang.annotation.Target} ==
* {@link java.lang.annotation.ElementType#TYPE} and
* {@link java.lang.annotation.Retention} ==
* {@link java.lang.annotation.RetentionPolicy#RUNTIME}.
*
* @see org.apache.lucene.gdata.server.registry.GDataServerRegistry
* @see org.apache.lucene.gdata.server.registry.ComponentType
* @see org.apache.lucene.gdata.server.registry.SuperType
*
*
* @author Simon Willnauer
*
*/
@Target( { TYPE })
@Retention(value = RUNTIME)
public @interface Component {
/**
* @see ComponentType
* @return - the component type
*/
ComponentType componentType();
}
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