Broadcast

Broadcasts can be emitted to multiple worker processes in the system, allowing each worker process to execute business logic

Create Broadcast

For example, create a broadcast echo in the module demo-student, so that each worker process outputs Hello world to the console

1. Cli Command

$ vona :create:bean broadcast echo --module=demo-student

2. Menu Command

TIP

Context Menu - [Module Path]: Vona Bean/Broadcast

Broadcast Definition

export interface TypeBroadcastEchoJobData { message: string }

@Broadcast()
export class BroadcastEcho
  extends BeanBroadcastBase<TypeBroadcastEchoJobData>
  implements IBroadcastExecute<TypeBroadcastEchoJobData> {
  async execute(data: TypeBroadcastEchoJobData, isEmitter?: boolean) {
    if (!isEmitter) {
      console.log(`pid: ${process.pid} message: ${data.message}`);
    }
  }
}

• TypeBroadcastEchoJobData: Defines broadcast data
• execute: Outputs the message to the console

• execute parameters

Name	Description
data	Broadcast data
isEmitter	Whether it is the worker process emiting the broadcast

Emit Broadcast

class ControllerStudent {
  test() {
    const data = { message: 'Hello world' };
    console.log(`pid: ${process.pid} message: ${data.message}`);
    this.scope.broadcast.echo.emit(data);
  }
}

• this.scope.broadcast.echo: Retrieves the broadcast instance through the module scope
• emit: Emits the broadcast, passing in the broadcast data

TIP

If business logic has already been executed in the current worker process, you can check isEmitter in the execute method to ignore the worker process that emit the broadcast

Broadcast Parameters

Parameters can be configured for broadcasts

@Broadcast({
  instance: true,
  transaction: true,
})
class BroadcastEcho {}

Name	Description
instance	Whether to ensure that the instance has been initialized. Defaults to true
transaction	Whether to enable database transaction

• instance: VonaJS supports multi-instance/multi-tenancy. If the broadcast's business logic requires manipulating instance data, then you need to ensure that the instance has been initialized
• transaction: If set to true, the system will automatically put the broadcast's execute method into a database transaction

App Config

Broadcast parameters can be configured in App Config

src/backend/config/config/config.ts

// onions
config.onions = {
  broadcast: {
    'demo-student:echo': {
      instance: true,
      transaction: true,
    },
  },
};

Inspect

You can directly inspect the currently effective broadcast list

class ControllerStudent {
  @Web.get('test')
  test() {
+   this.bean.onion.broadcast.inspect();
  }
}

• this.bean.onion: Get the global Service instance onion
• .broadcast: Get the Service instance related to the broadcast
• .inspect: Output the currently effective broadcast list

When accessing the test API, the currently effective broadcast list will be automatically output to the console, as shown below: