The Application Integration Framework (AIF) uses a set of services to asynchronously process inbound and outbound documents:
The use of these services are determined by which AIF adapter you are using.
File system adapter
As you can see from this chart, there is no need for you to run and schedule the AIFGateway services if you are using the BizTalk adapter. If you are using the BizTalk adapter and only bringing in inbound documents, then you would only have to run the AifInboundProcessingService as that service will bring in the document from BizTalk, process the business logic in AX, and produce the response message if required. The use of the AifOutboundProcessingService is only needed if you are producing outbound documents such as sending out Trade Agreements, etc.