Server Side Signals

Signals re used to notify the local object about changes on the remote object.

ApiGear Object Model

Signals can be modeled using ApiGear as signals of an interface.

name: org.demos

interfaces:
  - name: Echo
    signals:
      - name: shutdown
        params:
        - name: timeout
          type: int

The resulting code will look somehow like this and most often will require a lambda function to be used for the notification.

// org.demos.js
class Echo {
  onShutdown(callback)	
}
const echo = new Echo()
echo.onShutdown( (timeout) => {
	console.log('timeout: ', timeout);
})

Protocol Flow

To receive signals the local object needs to be linked to the remote object first.

--> [ LINK, "org.demos.Echo"]

Then the remote object can send at any time signals to the linked client objects and notify them on changes.

<-- [ SIGNAL, "org.demos.Echo/shutdown", [10]]

To stop receiving signals, just unlink the remote object.

--> [ UNLINK, "org.demos.Echo"]

Sequence Diagram

After an object is linked server side signals will be send.