There are two approaches often used for the specification of communication-intensive systems: an operational approach, that describes how interactions are structured and a declarative one, in which only the governing conditions for correct interactions are defined. Although these two paradigms have evolved independently, we believe that they should not be disjoint. In fact, the correctness of communication-intensive systems depends on the complex interplay of declarative and operational features. Hence, it is desirable to devise a framework in which properties and reasoning techniques can be transferred between paradigms. Herein, we describe our efforts, part of my PhD studies, to develop such framework. We focus on session-based concurrency and its associated specification language: the pi-calculus. Via encodings, treated as formal compilers, we have shown how to abstract the main communication structures from session pi-calculi and integrate them into declarative languages.