org.apache.kafka.common.protocol.Message Maven / Gradle / Ivy
/*
* 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.kafka.common.protocol;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.JsonNode;
import org.apache.kafka.common.protocol.types.RawTaggedField;
import org.apache.kafka.common.protocol.types.Struct;
import java.util.List;
/**
* An object that can serialize itself. The serialization protocol is versioned.
* Messages also implement toString, equals, and hashCode.
*/
public interface Message {
/**
* Returns the lowest supported API key of this message, inclusive.
*/
short lowestSupportedVersion();
/**
* Returns the highest supported API key of this message, inclusive.
*/
short highestSupportedVersion();
/**
* Returns the number of bytes it would take to write out this message.
*
* @param cache The serialization size cache to populate.
* @param version The version to use.
*
* @throws {@see org.apache.kafka.common.errors.UnsupportedVersionException}
* If the specified version is too new to be supported
* by this software.
*/
int size(ObjectSerializationCache cache, short version);
/**
* Writes out this message to the given Writable.
*
* @param writable The destination writable.
* @param cache The object serialization cache to use. You must have
* previously populated the size cache using #{Message#size()}.
* @param version The version to use.
*
* @throws {@see org.apache.kafka.common.errors.UnsupportedVersionException}
* If the specified version is too new to be supported
* by this software.
*/
void write(Writable writable, ObjectSerializationCache cache, short version);
/**
* Reads this message from the given Readable. This will overwrite all
* relevant fields with information from the byte buffer.
*
* @param readable The source readable.
* @param version The version to use.
*
* @throws {@see org.apache.kafka.common.errors.UnsupportedVersionException}
* If the specified version is too new to be supported
* by this software.
*/
void read(Readable readable, short version);
/**
* Reads this message from a Struct object. This will overwrite all
* relevant fields with information from the Struct.
*
* @param struct The source struct.
* @param version The version to use.
*
* @throws {@see org.apache.kafka.common.errors.UnsupportedVersionException}
* If the specified struct can't be processed with the
* specified message version.
*/
void fromStruct(Struct struct, short version);
/**
* Writes out this message to a Struct.
*
* @param version The version to use.
*
* @throws {@see org.apache.kafka.common.errors.UnsupportedVersionException}
* If the specified version is too new to be supported
* by this software.
*/
Struct toStruct(short version);
/**
* Reads this message from a Jackson JsonNode object. This will overwrite
* all relevant fields with information from the Struct.
*
* For the most part, we expect every JSON object in the input to be the
* correct type. There is one exception: we will deserialize numbers
* represented as strings. If the numeric string begins with 0x, we will
* treat the number as hexadecimal.
*
* Note that we expect to see NullNode objects created for null entries.
* Therefore, please configure your Jackson ObjectMapper with
* setSerializationInclusion({@link JsonInclude.Include#ALWAYS}).
* Other settings may silently omit the nulls, which is not the
* semantic that Kafka RPC uses. (Including a field and setting it to
* null is different than not including the field.)
*
* @param node The source node.
* @param version The version to use.
*
* @throws {@see org.apache.kafka.common.errors.UnsupportedVersionException}
* If the specified JSON can't be processed with the
* specified message version.
*/
void fromJson(JsonNode node, short version);
/**
* Convert this message to a JsonNode.
*
* Note that 64-bit numbers will be serialized as strings rather than as integers.
* The reason is because JavaScript can't represent numbers above 2**52 accurately.
* Therefore, for maximum interoperability, we represent these numbers as strings.
*
* @param version The version to use.
*
* @throws {@see org.apache.kafka.common.errors.UnsupportedVersionException}
* If the specified version is too new to be supported
* by this software.
*/
JsonNode toJson(short version);
/**
* Returns a list of tagged fields which this software can't understand.
*
* @return The raw tagged fields.
*/
List unknownTaggedFields();
/**
* Make a deep copy of the message.
*
* @return A copy of the message which does not share any mutable fields.
*/
Message duplicate();
}