CODESAMPLE

Microkernel - TypeScript

Microkernel TypeScript

The Microkernel pattern aims to create a minimal core system (“microkernel”) and extend functionality through plug-ins (“kernel modules”). This promotes modularity, flexibility, and testability. Our TypeScript implementation defines an EventBus as the microkernel, handling event dispatch. Independent Plugin classes implement specific features, registering event handlers with the EventBus. The main application starts the bus and then loads plugins, injecting the bus dependency. This adheres to TypeScript’s class-based OOP style and leverages dependency injection for loose coupling. The use of interfaces (Plugin, EventHandler) enforces clear contracts between components.

// Event Bus (Microkernel)
interface EventHandler {
  (data: any): void;
}

class EventBus {
  private handlers: { [event: string]: EventHandler[] } = {};

  on(event: string, handler: EventHandler) {
    this.handlers[event] = this.handlers[event] || [];
    this.handlers[event].push(handler);
  }

  emit(event: string, data: any) {
    const handlers = this.handlers[event];
    if (handlers) {
      handlers.forEach(handler => handler(data));
    }
  }
}

// Plugin Interface
interface Plugin {
  start(bus: EventBus): void;
}

// Example Plugin 1: Logging
class LoggingPlugin implements Plugin {
  start(bus: EventBus) {
    bus.on('data.received', (data: any) => {
      console.log('Logging Plugin: Data received:', data);
    });
  }
}

// Example Plugin 2: Data Processing
class DataProcessingPlugin implements Plugin {
  start(bus: EventBus) {
    bus.on('data.received', (data: any) => {
      const processedData = { ...data, processed: true };
      console.log('Data Processing Plugin: Data processed:', processedData);
      bus.emit('data.processed', processedData);
    });

    bus.on('data.processed', (data: any) => {
      console.log('Data Processing Plugin:  Event Received - Data is completely processed');
    });
  }
}



// Main Application
class Application {
  private bus: EventBus;
  private plugins: Plugin[] = [];

  constructor() {
    this.bus = new EventBus();
  }

  addPlugin(plugin: Plugin) {
    this.plugins.push(plugin);
  }

  start() {
    this.plugins.forEach(plugin => plugin.start(this.bus));
    this.bus.emit('app.started', 'Application is running'); //Initial event
  }
}

// Usage
const app = new Application();
app.addPlugin(new LoggingPlugin());
app.addPlugin(new DataProcessingPlugin());
app.start();

app.bus.emit('data.received', { message: 'Hello, Microkernel!' });