RE: AX2012 integration methods besides Files and webservices
Why exactly do you want to throw away the best and most common options? AIF also supports MSMQ, but it's likely not applicable to you. Or you could build something proprietary, similar to web services but not following any WS standards. But why would you do that? It sounds like wasting money to build something that nobody else knows how to use.
If you have business requirements that prevents using web services and files, share them with us, so we can take them into account. If you don't have any business reasons, simply abandon the idea.
When we know your business requirements, we should be able to suggest a realistic design. For example, maybe you don't want web services, because you think that it means a synchronous call between systems, but it's not necessarily true. For example, you can put a message to a Service Bus Queue and make web service calls to get messages from the queue. You're still using web services (among other things), but you've achieved benefits like time-decoupling, that you wouldn't have available if you used direct web services calls.
By the way, is there any reason why you attached "Enterprise Portal" tag?