How do you go about proxying REST style requests to a SOAP backend?
A harder case is when you have a "service" layer which also has a large collection of queries at various levels of abstraction.
These map poorly into resources, where you want a single level of abstraction per resource. And they map badly to legacy consumers, who've grown comfortable to having a collection of special knobs and dials perfectly shaped for their exact needs.
It does suck a bit, I've also sent Layer 7 into production which is just as bad as Axway. Typical Vendorware.
The AWS Gateway is pretty enticing. Solves lots of the API Gateway problem space very quickly and super cheap. We could run our production instance for about $2 a month I reckon, vs a 6 figure sum for the vendor tech.