Systems, gateway computers, and methods for using a gateway abstraction layer and application platform interfaces for conducting service transactions are disclosed. A gateway abstraction layer computers can receive service requests in multiple message formats or communication protocols, transform those service requests into other message formats to process the service using one or more networks or third-party service providers. The results of the service request can then be translated back to the message format in which the original service request was received. The gateway abstraction layer can be maintained using update messages received from service providers.