ST4MP: A Blueprint of Multiparty Session Typing for Multilingual Programming

Abstract

Multiparty session types (MPST) constitute a method to simplify construction and analysis of distributed systems. The idea is that well-typedness of processes at compile-time (statically) entails deadlock freedom and protocol compliance of their sessions of communications at execution-time (dynamically). In practice, the premier approach to apply the MPST method in combination with mainstream programming languages has been based on API generation. However, existing MPST tools support only unilingual programming (homogeneity), while many real-world distributed systems are engineered using multilingual programming (heterogeneity). In this paper, we present a blueprint of ST4MP: a tool to apply the MPST method in multilingual programming, based on API generation. G = m m m_w w w 1 :Work . m m m_w w w 2 :Work . (w w w 1 _m m m:Done . end 9 w w w 2 _m m m:Done . end) Global type p_q:t.G specifies the communication of a value of type t i through the channel from role p to role q, followed by G. Global type G 1 9 G 2 specifies the free interleaving of G 1 and G 2 . Global type end specifies termination.The following local types specify the master (n = 2) and a worker (any n): L m m m = m m mw w w 1 !Work . m m mw w w 2 !Work . (w w w 1 m m m?Done . end 9 w w w 2 m m m?Done . end)L w w wi = m m mw w w i ?Work . w w w i m m m !Done . end Local types pq !t.L and pq?t.L specify the send and receive of a value of type t through the channel from role p to role q, followed by L. Local types L 1 9 L 2 and end are similar to the corresponding forms of global types. In general, a local type L r for role r is mechanically constructed by projecting a global type G onto r, using a recursive function that traverses G's structure. Roughly: every communication in which r participates as sender is preserved as a send in L r ; every communication in which r participates as receiver is preserved as a receive in L r ; every communication in which r does not participate is omitted from L r .The following processes implement the master (n = 2) and a worker (any n): P m m m = m m mw w w 1 !work("grep -o -i foo file.txt | wc -l") . m m mw w w 2 !work("grep -o -i bar file.txt | wc -l") . (w w w 1 m m m? _ :Done . end 9 w w w 2 m m m? _ :Done . end) P w w wi = m m mw w w i ?x:Work . w w w i m m m !do(x) . endProcesses pq !e.P and pq?x:t.P implement the send and receive of the value of expression e (evaluated at the sender) through the channel from role p to role q into variable x of type t (stored at the receiver), followed by P . Processes P 1 9 P 2 and end are similar to the corresponding forms of global/local types.

Behavioural Types for Heterogeneous Systems (Position Paper)

“…Only very little work has attempted to address heterogeneous session typing. Jongmans and Proença [27] describe the design of a system called ST4MP that aims to support multi-lingual programming through the established API generation approach [23]; the idea is to generate multiple compatible APIs for different languages from a given global type specification. In contrast to this position paper, ST4MP supports a base multiparty session typing discipline without any advanced language features (e.g., timing or refinement types), and does not make use of any form of runtime checking.…”

Verification and Validation of Concurrent and Distributed Heterogeneous Systems (Track Summary)

“…In ST4MP: A Blueprint of Multiparty Session Typing for Multilingual Programming [10], the authors Sung-Shik Jongmans and José Proença provide a multiparty session types (MPST) method to simplify the construction and analysis of distributed systems implemented in multiple programming languages. In order to verify processes in such a heterogeneous setting, the authors generate API in multiple languages, by their newly introduced tool called ST4MP "Session Types Fo(u)r Multilingual Programming".…”