Is an open source. Its language is based on SQL and has some extensions, such as: on pattern, and it is embeddable component in Java application.

/**
* Keep all DeliveryBid in a named window
* Based upon completion the elements will get updated / removed later
*/
create window DeliveryBidW.win:keepall() as select requestId, store, driver, pickupTime, 0 as ranking, '' as status from DeliveryBid;

/**
* Specification subject to interpretation
* - we keep the driver per pickup time and not per ranking, or per a more complex domain level logic
* For an automatic store, 2 minutes after a BidRequest we assign the driver with the earliest pickup
*/
on pattern[every b=BidRequest(storeManual=false) -> timer:interval(2 min)]
insert into Assignment
select d.*, b.deliveryTime as deliveryTime
from
DeliveryBidW d
where requestId = b.requestId
order by pickupTime asc limit 1;

You could find here a first version of the Esper EPL syntax for the primary use cases of  the FFD application.