To subscribe to notifications in a production environment, you must provide a callback URL with a valid SSL certificate to handle the notification. For development purposes, you can use a subscription proxy server provided by Google that forwards notifications to a non-SSL callback URL.
To use the subscription proxy, append your non-SSL callback URL to the proxy server's forwarding URL like this:
https://mirrornotifications.appspot.com/forward?url=<your_callback_url>
When you subscribe to a notification, specify the full URL that includes the forwarding service URL and your callback URL. For example:
POST /mirror/v1/subscriptions HTTP/1.1
Authorization: Bearer auth token
Content-Type: application/json
Content-Length: length
{
"collection": "timeline"
"userToken": "harold_penguin",
"operation": ["UPDATE"],
"callbackUrl": "https://mirrornotifications.appspot.com/forward?url=http://example.com/notify/callback"
}