  The Internet stack is not a complete description of the resources and
services needed to implement distributed applications, as it only accounts for
communication services and the protocols that are defined to deliver them. This
paper presents an account of the current distributed application architecture
using a formal model of strictly layered systems, meaning that services in any
layer can only depend on services in the layer immediately below it. By mapping
a more complete Internet-based application stack that includes necessary
storage and processing resources to this formal model, we are able to apply the
Hourglass Theorem in order to compare alternative approaches in terms of their
"deployment scalability." In particular, we contrast the current distributed
application stack with Exposed Buffer Architecture, which has a converged
spanning layer that allows for less-than-complete communication connectivity
(exposing lower layer topology), but which also offers weak storage and
processing services. This comparison shows that Exposed Buffer Architecture can
have deployment scalability greater than the current distributed application
stack while also providing minimally requisite storage and processing services.
