org.apache.hadoop.ipc.ProtocolInfo Maven / Gradle / Ivy
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.ipc;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
/**
* The protocol name that is used when a client and server connect.
* By default the class name of the protocol interface is the protocol name.
*
* Why override the default name (i.e. the class name)?
* One use case overriding the default name (i.e. the class name) is when
* there are multiple implementations of the same protocol, each with say a
* different version/serialization.
* In Hadoop this is used to allow multiple server and client adapters
* for different versions of the same protocol service.
*/
@Retention(RetentionPolicy.RUNTIME)
public @interface ProtocolInfo {
String protocolName(); // the name of the protocol (i.e. rpc service)
long protocolVersion() default -1; // default means not defined use old way
}