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‎tolerant-reader/src/main/java/com/iluwatar/App.java‎

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/**
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*
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* Tolerant Reader is an integration pattern that helps creating robust communication
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* systems. The idea is to be as tolerant as possible when reading data from another
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* service. This way, when the communication schema changes, the readers must not break.
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*
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* In this example we use Java serialization to write representations of RainbowFish
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* objects to file. RainbowFish is the initial version which we can easily read and
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* write using RainbowFishSerializer methods. RainbowFish then evolves to RainbowFishV2
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* and we again write it to file with a method designed to do just that. However, the reader
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* client does not know about the new format and still reads with the method designed for
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* V1 schema. Fortunately the reading method has been designed with the Tolerant Reader
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* pattern and does not break even though RainbowFishV2 has new fields that are serialized.
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*
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*/
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public class App {

‎tolerant-reader/src/main/java/com/iluwatar/RainbowFish.java‎

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import java.io.Serializable;
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/**
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*
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* RainbowFish is the initial schema
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*
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*/
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public class RainbowFish implements Serializable {
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private static final long serialVersionUID = 1L;

‎tolerant-reader/src/main/java/com/iluwatar/RainbowFishSerializer.java‎

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import java.util.HashMap;
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import java.util.Map;
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/**
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*
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* RainbowFishSerializer provides methods for reading and writing RainbowFish objects to file.
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* Tolerant Reader pattern is implemented here by serializing maps instead of RainbowFish objects.
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* This way the reader does not break even though new properties are added to the schema.
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*
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*/
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public class RainbowFishSerializer {
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/**
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* Write V1 RainbowFish to file
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* @param rainbowFish
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* @param filename
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* @throws IOException
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*/
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public static void writeV1(RainbowFish rainbowFish, String filename) throws IOException {
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Map<String, String> map = new HashMap<>();
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map.put("name", rainbowFish.getName());
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fileOut.close();
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}
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/**
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* Write V2 RainbowFish to file
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* @param rainbowFish
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* @param filename
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* @throws IOException
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*/
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public static void writeV2(RainbowFishV2 rainbowFish, String filename) throws IOException {
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Map<String, String> map = new HashMap<>();
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map.put("name", rainbowFish.getName());
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fileOut.close();
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}
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/**
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* Read V1 RainbowFish from file
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* @param filename
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* @return
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* @throws IOException
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* @throws ClassNotFoundException
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*/
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public static RainbowFish readV1(String filename) throws IOException, ClassNotFoundException {
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Map<String, String> map = null;
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FileInputStream fileIn = new FileInputStream(filename);

‎tolerant-reader/src/main/java/com/iluwatar/RainbowFishV2.java‎

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package com.iluwatar;
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/**
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*
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* RainbowFishV2 is the evolved schema
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*
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*/
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public class RainbowFishV2 extends RainbowFish {
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private static final long serialVersionUID = 1L;

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