Feature Request: Publish pbj-compiler JAR to Maven Central

[rbair23]

Feature Request: Publish pbj-compiler JAR to Maven Central

Summary

Request to publish pbj-compiler as a standalone JAR artifact to Maven Central, separate from the Gradle plugin, to enable usage in Maven builds and other build systems.

Current Situation

Currently, PBJ provides:

• ✅ pbj-runtime published to Maven Central (version 0.11.15 available)
• ✅ Gradle plugin com.hedera.pbj.pbj-compiler published to Gradle Plugin Portal
• ❌ pbj-compiler JAR last published to Maven Central at version 0.7.5 (August 2023)

Problem

Projects using Maven or other build systems cannot easily use PBJ for code generation because:

1. The pbj-compiler JAR is not published to Maven Central for recent versions (0.8.0+)
2. The compiler is only available as a Gradle plugin
3. This forces Maven projects to either:
   • Use outdated pbj-compiler (0.7.5)
   • Clone and build pbj-compiler from source using Gradle
   • Commit generated code to version control
   • Use Gradle just for code generation (mixing build tools)

Proposed Solution

Publish pbj-compiler as a standalone JAR artifact to Maven Central alongside pbj-runtime, similar to how protoc is published separately from protobuf-maven-plugin.

Benefits

1. Build Tool Agnostic: Maven, Gradle, Ant, or any JVM build tool can use PBJ
2. Direct Invocation: Can be invoked via java -jar or programmatically via PbjCompiler.compileFilesIn()
3. Custom Integration: Users can integrate PBJ into custom build pipelines
4. Consistent Versioning: Keep pbj-compiler and pbj-runtime versions in sync

Suggested Structure

com.hedera.pbj:pbj-compiler:0.11.15      (the compiler library JAR)
com.hedera.pbj:pbj-compiler-gradle-plugin:0.11.15  (optional: the Gradle plugin wrapper)
com.hedera.pbj:pbj-runtime:0.11.15       (already published)

Use Case

A small POC project is using Maven. We need PBJ code generation but cannot use the Gradle plugin. The PbjCompiler class already has a clean API:

PbjCompiler.compileFilesIn(
    sourceFiles,
    mainOutputDir,
    testOutputDir,
    javaPackageSuffix,
    generateTestClasses
);

This could easily be invoked from Maven via exec-maven-plugin if the JAR were published.

Alternative Workarounds

If publishing the JAR is not feasible, alternatives include:

1. Provide a CLI wrapper with main() method
2. Publish documentation on building pbj-compiler locally
3. Provide Maven plugin alongside Gradle plugin

References

• Gradle Plugin: https://plugins.gradle.org/plugin/com.hedera.pbj.pbj-compiler
• Maven Central pbj-runtime: https://repo1.maven.org/maven2/com/hedera/pbj/pbj-runtime/
• Maven Central pbj-compiler (outdated): https://repo1.maven.org/maven2/com/hedera/pbj/pbj-compiler/

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[anthony-swirldslabs]

Related issue: #124