I’ve written a bot application that subscribes to a pubsub topic and upon receipt of a new entry, forwards an instant message to all subscribed end users.
This works fine in almost all cases. However, there is one bot that is unique in that it almost always has 2 or 3 entries published to its pubsub topic simultaneously. This bot works fine when the end users are online to receive their messages. In the case that they are offline, the messages are never delivered when they log on next.
These offline messages are only ‘dropped’ in the case where 2 or more instant messages are sent to the server at almost the exact same moment in time from the same user intended for the same recipient.