Of a subscription: An existing subscription is active if it is ready to accept webhook deliveries. Contrast with inactive. A subscription in this state may transaction to inactive at any time.
Of a subscription: Does the subscription apply to some piece of data, including permission checks? Only active subscriptions should be applicable.

A customization point for a subscription. A dialect is used to create and populate the HTTP request.

Of an object: Written out in a format suitable for use in an HTTP REST API, such as JSON, using nti.externalization.
Of a subscription: An existing subscription is inactive if webhook deliviries will no longer be attempted to it. It may transition back to active at any time.

A target to which webhooks will be delivered.

Subscriptions may be either active or inactive. Only active subscriptions will result in delivery attempts.

In addition to capturing the target URL and HTTP method to use, a subscription knows the dialect to use, along with the security restrictions to apply. It also has a delivery history.

Of a subscription: The URL to which the HTTP request is sent.
An zope.interface.interfaces.IObjectEvent, when notified through zope.event.notify() may trigger a matching subscription to attempt a delivery.