Protobuf madness with multiple languages

hello.proto

syntax = "proto3";

package hello;

option java_package = "com.tutorial.hello";

message Hello {
    string message = 1;
}

hello_read.py

import hello_pb2
import sys


def main():
    hello = hello_pb2.Hello()

    filename = sys.argv[1]

    print(f"Parsing hello info from file with Python: {filename}")

    with open(sys.argv[1], "rb") as f:
        hello.ParseFromString(f.read())

    print(f"Parsed hello info with following data:\n{hello}")


if __name__ == '__main__':
    main()

HelloWriter.java

package com.tutorial.hello;

import com.tutorial.hello.HelloOuterClass.Hello;

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class HelloWriter {
    public static void main(String[] args) throws IOException {
        Hello hello = Hello.newBuilder()
                .setMessage("Hello world")
                .build();

        String filename = args[0];
        System.out.println("Saving hello info to file with Java: " + filename);

        try (FileOutputStream output = new FileOutputStream(filename)){
            hello.writeTo(output);
        }

        System.out.println("Saved hello info with following data to disk:\n" + hello);
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project
    xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.tutorial</groupId>
    <artifactId>hello</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>jar</packaging>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>

    <build>
        <sourceDirectory>.</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.13.0</version>
                <configuration>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <version>3.3.1</version>
                <configuration>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>com.google.protobuf</groupId>
            <artifactId>protobuf-java</artifactId>
            <version>4.28.3</version>
        </dependency>
    </dependencies>
</project>

requirements.txt

protobuf==5.28.3

run_e2e.sh

#!/bin/bash

protoc --java_out=. hello.proto
protoc --python_out=. hello.proto

mvn clean install

base="$HOME/.m2/repository"

my='1.0-SNAPSHOT'
my_jar="$base/com/tutorial/hello/$my/hello-$my.jar"

proto='4.28.3'
proto_jar="$base/com/google/protobuf/protobuf-java/$proto/protobuf-java-$proto.jar"

bin_file='hello.bin'

if [[ -f $bin_file ]]; then
    echo "Remove old $bin_file output to enforce a deterministic outcome"
    rm -f "$bin_file"
fi

java -cp "$my_jar:$proto_jar" com.tutorial.hello.HelloWriter "$bin_file"

python hello_read.py "$bin_file"

Inspired by this resource:

https://www.tutorialspoint.com/protobuf/protobuf_language_independence.htm