PF4J Spring Demo Application

This project demonstrates the integration of PF4J (Plugin Framework for Java) with Spring Boot, showcasing a plugin-based architecture for Java applications.

Project Overview

The application is a Spring Boot-based service that uses PF4J to manage plugins. It includes a simple REST API that aggregates responses from multiple plugins implementing a common interface.

Technology Stack

• Java 23
• Spring Boot 3.4.2
• PF4J 3.13.0
• PF4J-Spring 0.9.0
• Gradle 8.12.1

Project Structure

The project consists of several modules:

• Main Application: Core Spring Boot application that loads and manages plugins
• Commons: Shared interfaces and classes used by both the main application and plugins
• Extensions:
  • hello-plugin: Plugin that returns "Hello!" message
  • bye-plugin: Plugin that returns "Bye!" message

Building and Running

Prerequisites

• JDK 23 or later
• Gradle 8.12.1 or later

Build Instructions

1. Clone the repository
2. Build the project:

./gradlew build

This will:

• Build the main application
• Build all plugins
• Copy plugin JARs to the plugins directory

Running the Application

Start the application using:

./gradlew bootRun

API Endpoints

• GET /phrase: Returns concatenated phrases from all active plugins

Plugin Development

Creating New Plugins

1. Create a new module in the extensions directory
2. Implement the PhraseExtensionPoint interface
3. Add plugin metadata to the build configuration
4. Add the new module to settings.gradle.kts

Plugin Structure

Each plugin requires:

• Implementation of PhraseExtensionPoint
• Plugin metadata in build.gradle.kts:

  manifest {
      attributes["Plugin-Id"] = "plugin-id"
      attributes["Plugin-Version"] = project.version
      attributes["Plugin-Provider"] = "provider-name"
  }

Project Configuration

The project uses Gradle for build automation. Key configurations include:

• Java 23 toolchain
• Spring Boot dependencies
• PF4J integration
• Automatic plugin deployment