The Transaction Controller (DEX) is a proprietary service, it logs all data related to data transfers in the PDS ecosystem, responds to PDS requests to create Data Debits, authorises PDS-enabled applications and associated HAT Microserver Instructions (HMI), holds data transactions, verifies exchanges, and quickly, accurately, and securely sends and receives data between parties. The Transaction Controller service also logs the data contracts between PDA owners and PDA-enabled applications.