In the current system, we have a Scheduling Service that takes incoming HTTP API requests. It adds entries to a ScheduledTweetsDatabase.

The ScheduledTweetsDatabase is some kind of relational database with fields for eventID (string), userID (string), content (string), scheduledFor (timestamp), 


and sent (boolean). It is indexed on eventID and scheduledFor.

field    | eventID | userID | content | scheduledFor |  sent
         +---------+--------+---------+--------------+---------
type     | string  | string | string  |  timestamp   | boolean
indexed? | indexed |        |         |   indexed    |


An ExecutorService polls the ScheduledTweetsDatabase for events with a scheduledFor in the past and sent=False. It then publishes the content by sending a POST request to the public Tweet API and updates the event with sent=True in the ScheduledTweetsDatabase.