You don't necessarily need to use Automation Studio. You have a few options here:
- Define a schedule within the Event in Journey Builder to check the Data Source for new records (refer to this screenshot),
- Include a Fire Event activity in your Automation, or
- Use the Events API method (described below).
With both options 1 and 2, Marketing Cloud will set a "high watermark" on the Data Extension each time it processes records.
For example, if you have 50 records in your DE, then when the Event is fired (either by the Event schedule or the Fire Event Activity in your Automation) then all records will be processed and the high watermark will be set to the 50 records. Then, if an additional 2 records are added to the DE (so you now have a total of 52 records in the DE), then the next time the Activity is fired, then only these 2 new records will enter the Interaction (assuming that they meet the Contact Filter Criteria defined in the Event).
Regarding the Events API method, while this isn't publicly documented for some peculiar reason, here it is:
Authorization: Bearer insertAccessTokenHere
insertAccessTokenHere is the accessToken obtained from the Fuel Authentication Service
insertContactKeyHere is the Contact Key defined by the cardinal relationship you created to the Contact Record in Contact Builder
InsertEventDefinitionKeyHere is the Event Definition Key used by the Event (once you create an event, you can retrieve this from the Events Administration page)
data are name/value pairs of data that will be added to the Data Source defined in the Event.
When this method is used, the data will be serialised into the Data Extension (defined as the Data Source) and the Contact will immediately enter the Interaction (assuming that they meet the Contact Filter Criteria defined in the Event).