If you are developing payment gateway software, that is intended for servicing of a large number of medium and small-size merchants, it is particularly important to implement a payment processing emulator within your payment gateway. The emulator allows your gateway to exchange data with the merchants without involving any real people. A high-quality feature rich payment processing emulator is capable of performing a variety of functions, related to verification of all data fields, present in the messages, incoming from the merchants. Beside responses to ordinary sale transactions (approvals or declines) a modern emulator should also support additional services (chargeback emulation, account updater, AVS, 3 D secure verification, and others).
Read more about payment processing emulators and their functions in the respective article on #Paylosophy.