A system has a gateway cluster having a gateway processor for communication with an external processor of an external user using a first protocol and data format. A non-transitory storage medium is configured for storing a database containing unfilled orders associated with the external user. An application cluster has a processor in communication with the storage medium for accessing the database. The gateway processor can communicate with the application processor using a second protocol and data format different from the first protocol and data format. The application processor is configured for fetching and aggregating unfilled orders from the database, and transmitting an aggregation of orders to the external processor via the gateway cluster in response to a number of unfilled orders being at least a threshold number, a size of the aggregation of orders being at least a threshold size, or expiration of a predetermined time period.