Subscriptions
You only need this resource for receiving webhooks, not for sending them!
A Subscription listens to webhook messages and delivers them to the Subscription's destination.
When a Subscription is created, a Binding ID must be specified. The Subscription will be bound to it and will listen to webhook messages published to that Binding.
Listening to topics
A Subscription only listens to the topics specified in the Subscription's topics attribute.
If that attribute is set to all available topics that an Binding offers,
then it will effectively listen to all published webhook messages of an
Binding.
If the topics attribute is an empty array, the Subscription will not
listen to any webhook messages, meaning that it will also not deliver
any webhooks.
Webhook delivery
Webhook messages are delivered via HTTPS POST requests to the destination_url
attribute of the Subscription.
Each published webhook message generates one POST request. An exception
to this rule is when the server at destination_url fails to properly
receive the request, in which case the webhook message could then be
re-delivered multiple times until a delivery succeeds.
See the Retrying page for more information.