181 results found
Boer F, Einar Broch J, Clarke D, et al., Scaling Future Software: The Manycore Challenge, ERCIM News, Vol: 2014
Subtyping in concurrency has been extensively studied since early 1990s asone of the most interesting issues in type theory. The correctness of subtyping relations hasbeen usually provided as the soundness for type safety. The converse direction, the com-pleteness, has been largely ignored in spite of its usefulness to de ne the largest subtypingrelation ensuring type safety. This paper formalises preciseness (i.e. both soundness andcompleteness) of subtyping for mobile processes and studies it for the synchronous and theasynchronous session calculi. We rst prove that the well-known session subtyping, thebranching-selection subtyping, is sound and complete for the synchronous calculus. Nextwe show that in the asynchronous calculus, this subtyping is incomplete for type-safety:that is, there exist session typesTandSsuch thatTcan safely be considered as a subtypeofS, butT6Sis not derivable by the subtyping. We then propose an asynchronous sub-typing system which is sound and complete for the asynchronous calculus. The methodgives a general guidance to design rigorous channel-based subtypings respecting desiredsafety properties. Both the synchronous and the asynchronous calculus are rst consid-ered with linear channels only, and then they are extended with session initialisations andcommunications of expressions (including shared channels).
Lange J, Ng N, Toninho B, et al., Fencing off Go: Liveness and Safety for Channel-based Programming (extended version)
Go is a production-level statically typed programming language whose designfeatures explicit message-passing primitives and lightweight threads, enabling(and encouraging) programmers to develop concurrent systems where componentsinteract through communication more so than by lock-based shared memoryconcurrency. Go can only detect global deadlocks at runtime, but provides nocompile-time protection against all too common communication mismatches orpartial deadlocks. This work develops a static verification framework forliveness and safety in Go programs, able to detect communication errors andpartial deadlocks in a general class of realistic concurrent programs,including those with dynamic channel creation, unbounded thread creation andrecursion. Our approach infers from a Go program a faithful representation ofits communication patterns as a behavioural type. By checking a syntacticrestriction on channel usage, dubbed fencing, we ensure that programs are madeup of finitely many different communication patterns that may be repeatedinfinitely many times. This restriction allows us to implement procedures tocheck for liveness and safety in types which in turn approximates liveness andsafety in Go programs. We have implemented a type inference and liveness andsafety checks in a tool-chain and tested it against publicly available Goprograms. Note: This is a revised extended version of a paper that appeared in POPL2017, see page 13 for details.
Neykova R, Bocchi L, Yoshida N, Timed Runtime Monitoring for Multiparty Conversations, Electronic Proceedings in Theoretical Computer Science, EPTCS, ISSN: 2075-2180
Neykova R, Yoshida N, Multiparty session actors, Logical Methods in Computer Science, ISSN: 1860-5974
Actor coordination armoured with a suitable protocol description language has beena pressing problem in the actors community. We study the applicability of multiparty session type(MPST) protocols for verification of actor programs. We incorporate sessions to actors by introduc-ing minimum additions to the model such as the notion of actor roles and protocol mailboxes. Theframework uses Scribble, which is a protocol description language based on multiparty session types.Our programming model supports actor-like syntax and runtime verification mechanism guarantee-ing communication safety of the participating entities. An actor can implement multiple roles in asimilar way as an object can implement multiple interfaces. Multiple roles allow for cooperativeinter-concurrency in a single actor. We demonstrate our framework by designing and implement-ing a session actor library in Python and its runtime verification mechanism. Benchmark resultsdemonstrate that the runtime checks induce negligible overhead. We evaluate the applicability of ourverification framework to specify actor interactions by implementing twelve examples from an actorbenchmark suit.
Orchard D, Rice A, Oshmyan O, Evolving Fortran types with inferred units-of-measure, Journal of Computational Science, ISSN: 1877-7503
Pérez JA, Kouzapas D, Yoshida N, Core Higher-Order Session Processes: Tractable Equivalences and Relative Expressiveness, Logic in Computer Science
Scalas A, Dardha O, Hu R, et al., A Linear Decomposition of Multiparty Sessions for Safe Distributed Programming, 31st European Conference on Object-Oriented Programming (ECOOP 2017)
Bocchi L, Chen T-C, Demangeon R, et al., 2017, Monitoring networks through multiparty session types, THEORETICAL COMPUTER SCIENCE, Vol: 669, Pages: 33-58, ISSN: 0304-3975
Graversen E, Phillips I, Yoshida N, 2017, Towards a Categorical Representation of Reversible Event Structures, Publisher: OPEN PUBL ASSOC, Pages: 49-60, ISSN: 2075-2180
Hu R, Yoshida N, 2017, Explicit connection actions in multiparty session types, Pages: 116-133, ISSN: 0302-9743
© Springer-Verlag GmbH Germany 2017. This work extends asynchronous multiparty session types (MPST) with explicit connection actions to support protocols with optional and dynamic participants. The actions by which endpoints are connected and disconnected are a key element of real-world protocols that is not treated in existing MPST works. In addition, the use cases motivating explicit connections often require a more relaxed form of multiparty choice: these extensions do not satisfy the conservative restrictions used to ensure safety in standard syntactic MPST. Instead, we develop a modelling-based approach to validate MPST safety and progress for these enriched protocols. We present a toolchain implementation, for distributed programming based on our extended MPST in Java, and a core formalism, demonstrating the soundness of our approach. We discuss key implementation issues related to the proposed extensions: a practical treatment of choice subtyping for MPST progress, and multiparty correlation of dynamic binary connections.
Imai K, Yoshida N, Yuen S, 2017, Session-ocaml: A session-based library with polarities and lenses, Pages: 99-118, ISSN: 0302-9743
© IFIP International Federation for Information Processing 2017. We propose session-ocaml, a novel library for session-typed concurrent/distributed programming in OCaml. Our technique solely relies on parametric polymorphism, which can encode core session type structures with strong static guarantees. Our key ideas are: (1) polarised session types, which give an alternative formulation of duality enabling OCaml to automatically infer an appropriate session type in a session with a reasonable notational overhead; and (2) a parameterised monad with a data structure called ‘slots’ manipulated with lenses, which can statically enforce session linearity and delegations. We show applications of session-ocaml including a travel agency usecase and an SMTP protocol.
Kouzapas D, Perez JA, Yoshida N, 2017, Characteristic bisimulation for higher-order session processes, ACTA INFORMATICA, Vol: 54, Pages: 271-341, ISSN: 0001-5903
Lange J, Ng N, Toninho B, et al., 2017, Fencing off Go: Liveness and Safety for Channel-Based Programming, Publisher: ASSOC COMPUTING MACHINERY, Pages: 748-761, ISSN: 0362-1340
Lange J, Yoshida N, 2017, On the undecidability of asynchronous session subtyping, Pages: 441-457, ISSN: 0302-9743
© Springer-Verlag GmbH Germany 2017. Asynchronous session subtyping has been studied extensively in [9, 10, 28–31] and applied in [23, 32, 33, 35] . An open question was whether this subtyping relation is decidable. This paper settles the question in the negative. To prove this result, we first introduce a new sub-class of two-party communicating finite-state machines (CFSMs), called asynchronous duplex (ADs), which we show to be Turing complete. Secondly, we give a compatibility relation over CFSMs, which is sound and complete wrt. safety for ADs, and is equivalent to the asynchronous subtyping. Then we show that the halting problem reduces to checking whether two CFSMs are in the relation. In addition, we show the compatibility relation to be decidable for three sub-classes of ADs.
Neykova R, Bocchi L, Yoshida N, 2017, Timed runtime monitoring for multiparty conversations, FORMAL ASPECTS OF COMPUTING, Vol: 29, Pages: 877-910, ISSN: 0934-5043
Neykova R, Yoshida N, 2017, Let it recover: Multiparty protocol-induced recovery, Pages: 98-108
© 2017 ACM. Fault-tolerant communication systems rely on recovery strategies which are often error-prone (e.g. a programmer manually specifies recovery strategies) or inefficient (e.g. the whole system is restarted from the beginning). This paper proposes a static analysis based on multiparty session types that can efficiently compute a safe global state from which a system of interacting processes should be recovered. We statically analyse the communication flow of a program, given as a multiparty protocol, to extract the causal dependencies between processes and to localise failures. We formalise our recovery algorithm and prove its safety. A recovered communication system is free from deadlocks, orphan messages and reception errors. Our recovery algorithm incurs less communication cost (only affected processes are notified) and overall execution time (only required states are repeated). On top of our analysis, we design and implement a runtime framework in Erlang where failed processes and their dependencies are soundly restarted from a computed safe state. We evaluate our recovery framework on messagepassing benchmarks and a use case for crawling webpages. The experimental results indicate our framework outperforms a built-in static recovery strategy in Erlang when a part of the protocol can be safely recovered.
Orchard D, Yoshida N, 2017, Special Issue: PLACES 2016 foreword, JOURNAL OF LOGICAL AND ALGEBRAIC METHODS IN PROGRAMMING, Vol: 90, Pages: 1-1, ISSN: 2352-2208
Scalas A, Yoshida N, 2017, Multiparty Session Types, Beyond Duality (Abstract), Publisher: OPEN PUBL ASSOC, Pages: 37-38, ISSN: 2075-2180
Toninho B, Yoshida N, 2017, Certifying data in multiparty session types, JOURNAL OF LOGICAL AND ALGEBRAIC METHODS IN PROGRAMMING, Vol: 90, Pages: 61-83, ISSN: 2352-2208
Debois S, Hildebrandt T, Slaats T, et al., 2016, TYPE-CHECKING LIVENESS FOR COLLABORATIVE PROCESSES WITH BOUNDED AND UNBOUNDED RECURSION, LOGICAL METHODS IN COMPUTER SCIENCE, Vol: 12, ISSN: 1860-5974
Debois S, Hildebrandt T, Slaats T, et al., 2016, Type-checking liveness for collaborative processes with bounded and unbounded recursion, Logical Methods in Computer Science, Vol: 12
© S. Debois, T. Hildebrandt, T. Slaats, and N. Yoshida. We present the first session typing system guaranteeing request-response liveness properties for possibly non-terminating communicating processes. The types augment the branch and select types of the standard binary session types with a set of required responses, indicating that whenever a particular label is selected, a set of other labels, its responses, must eventually also be selected. We prove that these extended types are strictly more expressive than standard session types. We provide a type system for a process calculus similar to a subset of collaborative BPMN processes with internal (databased) and external (event-based) branching, message passing, bounded and unbounded looping. We prove that this type system is sound, i.e., it guarantees request-response liveness for dead-lock free processes. We exemplify the use of the calculus and type system on a concrete example of an infinite state system.
Dezani-Ciancaglini M, Ghilezan S, Jakšić S, et al., 2016, Denotational and operational preciseness of subtyping: A roadmap, Pages: 155-172, ISBN: 9783319307336
© Springer International Publishing Switzerland 2016. The notion of subtyping has gained an important role both in theoretical and applicative domains: in lambda and concurrent calculi as well as in object-oriented programming languages. The soundness and the completeness, together referred to as the preciseness of subtyping, can be considered from two different points of view: denotational and operational. The former preciseness is based on the denotation of a type, which is a mathematical object describing the meaning of the type in accordance with the denotations of other expressions from the language. The latter preciseness has been recently developed with respect to type safety, i.e. the safe replacement of a term of a smaller type when a term of a bigger type is expected. The present paper shows that standard proofs of operational preciseness imply denotational preciseness and gives an overview on this subject.
Dezani-Ciancaglini M, Ghilezan S, Jaksic S, et al., 2016, Precise subtyping for synchronous multiparty sessions, ELECTRONIC PROCEEDINGS IN THEORETICAL COMPUTER SCIENCE, Pages: 29-43, ISSN: 2075-2180
Honda K, Yoshida N, Carbone M, 2016, Multiparty Asynchronous Session Types, JOURNAL OF THE ACM, Vol: 63, ISSN: 0004-5411
Hu R, Yoshida N, 2016, Hybrid Session Verification Through Endpoint API Generation, 19th International Conference on Fundamental Approaches to Software Engineering (FASE) held as part of Annual European Joint Conferences on Theory and Practice of Software (ETAPS), Publisher: SPRINGER-VERLAG BERLIN, Pages: 401-418, ISSN: 0302-9743
Kouzapas D, Perez JA, Yoshida N, 2016, On the Relative Expressiveness of Higher-Order Session Processes, 25th European Symposium on Programming (ESOP) Held as Part of the European Joint Conferences on Theory and Practice of Software (ETAPS), Publisher: SPRINGER-VERLAG BERLIN, Pages: 446-475, ISSN: 0302-9743
Lange J, Yoshida N, 2016, Characteristic Formulae for Session Types, 22nd International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS) held as Part of the European Joint Conferences on Theory and Practice of Software (ETAPS), Publisher: SPRINGER-VERLAG BERLIN, Pages: 833-850, ISSN: 0302-9743
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