With distributed computing becoming ubiquitous in the modern era, safe
distributed programming is an open challenge.
To address this, multiparty session types (MPST) provide a typing discipline
for message-passing concurrency, guaranteeing
communication safety properties such as deadlock freedom.

While originally MPST focus on the communication aspects, and employ a
simple typing system for communication payloads, communication protocols in the
real world usually contain constraints on the payload.
We introduce refined multiparty session types (RMPST), an extension of
MPST,
that express data dependent protocols via refinement types on the
data types.

We provide an implementation of RMPST, in a toolchain called Session*, using
Scribble, a toolchain for multiparty protocols, and targeting F*,
a verification-oriented functional programming language.
Users can describe a protocol in Scribble
and implement the endpoints in F* using refinement-typed APIs
generated from the protocol.
The F* compiler can then statically verify the refinements.
Moreover, we use a novel approach of callback-styled API generation, providing
static linearity guarantees with the inversion of control.
We evaluate our approach with real world examples and show that it has little
overhead compared to a naive implementation, while guaranteeing safety
properties from the underlying theory.