4904d7eea0
* Add custom license header style in order to comply with Google's Checkstyle format * Update license headers to comply with Google's Checkstyle format
78 lines
3.7 KiB
Java
78 lines
3.7 KiB
Java
/*
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* The MIT License
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* Copyright © 2014-2019 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.tolerantreader;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.io.IOException;
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/**
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*
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* Tolerant Reader is an integration pattern that helps creating robust communication systems. The
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* idea is to be as tolerant as possible when reading data from another service. This way, when the
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* communication schema changes, the readers must not break.
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* <p>
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* In this example we use Java serialization to write representations of {@link RainbowFish} objects
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* to file. {@link RainbowFish} is the initial version which we can easily read and write using
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* {@link RainbowFishSerializer} methods. {@link RainbowFish} then evolves to {@link RainbowFishV2}
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* and we again write it to file with a method designed to do just that. However, the reader client
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* does not know about the new format and still reads with the method designed for V1 schema.
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* Fortunately the reading method has been designed with the Tolerant Reader pattern and does not
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* break even though {@link RainbowFishV2} has new fields that are serialized.
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*
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*/
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public class App {
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private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
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/**
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* Program entry point
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*/
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public static void main(String[] args) throws IOException, ClassNotFoundException {
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// Write V1
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RainbowFish fishV1 = new RainbowFish("Zed", 10, 11, 12);
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LOGGER.info("fishV1 name={} age={} length={} weight={}", fishV1.getName(),
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fishV1.getAge(), fishV1.getLengthMeters(), fishV1.getWeightTons());
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RainbowFishSerializer.writeV1(fishV1, "fish1.out");
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// Read V1
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RainbowFish deserializedFishV1 = RainbowFishSerializer.readV1("fish1.out");
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LOGGER.info("deserializedFishV1 name={} age={} length={} weight={}",
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deserializedFishV1.getName(), deserializedFishV1.getAge(),
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deserializedFishV1.getLengthMeters(), deserializedFishV1.getWeightTons());
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// Write V2
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RainbowFishV2 fishV2 = new RainbowFishV2("Scar", 5, 12, 15, true, true, true);
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LOGGER.info(
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"fishV2 name={} age={} length={} weight={} sleeping={} hungry={} angry={}",
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fishV2.getName(), fishV2.getAge(), fishV2.getLengthMeters(), fishV2.getWeightTons(),
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fishV2.getHungry(), fishV2.getAngry(), fishV2.getSleeping());
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RainbowFishSerializer.writeV2(fishV2, "fish2.out");
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// Read V2 with V1 method
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RainbowFish deserializedFishV2 = RainbowFishSerializer.readV1("fish2.out");
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LOGGER.info("deserializedFishV2 name={} age={} length={} weight={}",
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deserializedFishV2.getName(), deserializedFishV2.getAge(),
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deserializedFishV2.getLengthMeters(), deserializedFishV2.getWeightTons());
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}
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}
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