Adding EventLogger to a Jupyter application

To begin using Jupyter Events in your Python application, create an instance of the EventLogger object in your application.

from jupyter_core.application import JupyterApp
from jupyter_events import EventLogger
from jupyter_events import Event


class MyApplication(JupyterApp):

    classes = [EventLogger, ...]
    eventlogger = Instance(EventLogger)

    def initialize(self, *args, **kwargs):
        self.eventlogger = EventLogger(parent=self)
        ...

Register an event schema with the logger.

        schema = """
        $id: http://myapplication.org/my-method
        version: 1
        title: My Method Executed
        description: My method was executed one time.
        properties:
        msg:
            title: Message
            type: string
        """

        self.eventlogger.register_event_schema(
            schema=schema
        )

Call .emit(...) within the application to emit an instance of the event.

    def my_method(self):
        # Do something
        ...
        # Emit event telling listeners that this event happened.
        self.eventlogger.emit(schema_id="myapplication.org/my-method", data={"msg": "Hello, world!"})
        # Do something else...
        ...

Great! Now your application is logging events from within. Deployers of your application can configure the system to listen to this event using Jupyter’s configuration system. This usually means reading a jupyter_config.py file like this:

# A Jupyter
from logging import StreamHandler

handler = StreamHandler()
c.EventLogger.handlers = [handler]

Now when we run our application and call the method, the event will be emitted to the console:

app = MyApplication.launch_instance(config_file="jupyter_config.py")
app.my_method()

{'__timestamp__': '2022-08-09T17:15:27.458048Z',
 '__schema__': 'myapplication.org/my-method',
 '__schema_version__': 1,
 '__metadata_version__': 1,
 'msg': 'Hello, world!'}