202 research outputs found
A Modular Toolkit for Distributed Interactions
We discuss the design, architecture, and implementation of a toolkit which
supports some theories for distributed interactions. The main design principles
of our architecture are flexibility and modularity. Our main goal is to provide
an easily extensible workbench to encompass current algorithms and incorporate
future developments of the theories. With the help of some examples, we
illustrate the main features of our toolkit.Comment: In Proceedings PLACES 2010, arXiv:1110.385
On Asynchronous Session Semantics
This paper studies a behavioural theory of the π-calculus with session types under the fundamental principles of the practice of distributed computing — asynchronous communication which is order-preserving inside each connection (session), augmented with asynchronous inspection of events (message arrivals). A new theory of bisimulations is introduced, distinct from either standard
asynchronous or synchronous bisimilarity, accurately capturing the semantic nature of session-based asynchronously communicating processes augmented with
event primitives. The bisimilarity coincides with the reduction-closed barbed congruence. We examine its properties and compare them with existing semantics.
Using the behavioural theory, we verify that the program transformation of multithreaded into event-driven session based processes, using Lauer-Needham duality,
is type and semantic preserving
Session-Based Programming for Parallel Algorithms: Expressiveness and Performance
This paper investigates session programming and typing of benchmark examples
to compare productivity, safety and performance with other communications
programming languages. Parallel algorithms are used to examine the above
aspects due to their extensive use of message passing for interaction, and
their increasing prominence in algorithmic research with the rising
availability of hardware resources such as multicore machines and clusters. We
contribute new benchmark results for SJ, an extension of Java for type-safe,
binary session programming, against MPJ Express, a Java messaging system based
on the MPI standard. In conclusion, we observe that (1) despite rich libraries
and functionality, MPI remains a low-level API, and can suffer from commonly
perceived disadvantages of explicit message passing such as deadlocks and
unexpected message types, and (2) the benefits of high-level session
abstraction, which has significant impact on program structure to improve
readability and reliability, and session type-safety can greatly facilitate the
task of communications programming whilst retaining competitive performance
Parameterised Multiparty Session Types
For many application-level distributed protocols and parallel algorithms, the
set of participants, the number of messages or the interaction structure are
only known at run-time. This paper proposes a dependent type theory for
multiparty sessions which can statically guarantee type-safe, deadlock-free
multiparty interactions among processes whose specifications are parameterised
by indices. We use the primitive recursion operator from G\"odel's System T to
express a wide range of communication patterns while keeping type checking
decidable. To type individual distributed processes, a parameterised global
type is projected onto a generic generator which represents a class of all
possible end-point types. We prove the termination of the type-checking
algorithm in the full system with both multiparty session types and recursive
types. We illustrate our type theory through non-trivial programming and
verification examples taken from parallel algorithms and Web services usecases.Comment: LMCS 201
Foundations of Session Types and Behavioural Contracts
International audienceBehavioural type systems, usually associated to concurrent or distributed computations, encompass concepts such as interfaces, communication protocols, and contracts, in addition to the traditional input/output operations. The behavioural type of a software component specifies its expected patterns of interaction using expressive type languages, so that types can be used to determine automatically whether the component interacts correctly with other components. Two related important notions of behavioural types are those of session types and behavioural contracts. This paper surveys the main accomplishments of the last twenty years within these two approaches
Behavioural Types for Actor Systems
Recent mainstream programming languages such as Erlang or Scala have renewed
the interest on the Actor model of concurrency. However, the literature on the
static analysis of actor systems is still lacking of mature formal methods. In
this paper we present a minimal actor calculus that takes as primitive the
basic constructs of Scala's Actors API. More precisely, actors can send
asynchronous messages, process received messages according to a pattern
matching mechanism, and dynamically create new actors, whose scope can be
extruded by passing actor names as message parameters. Drawing inspiration from
the linear types and session type theories developed for process calculi, we
put forward a behavioural type system that addresses the key issues of an actor
calculus. We then study a safety property dealing with the determinism of
finite actor com- munication. More precisely, we show that well typed and
balanced actor systems are (i) deadlock-free and (ii) any message will
eventually be handled by the target actor, and dually no actor will
indefinitely wait for an expected messag
220505
Construction and analysis of distributed systems is difficult. Multiparty session types (MPST) constitute a method to make it easier. The idea is to use type checking to statically prove deadlock freedom and protocol compliance of communicating processes. In practice, the premier approach to apply the MPST method in combination with mainstream programming languages has been based on API generation. In this paper (pearl), we revisit and revise this approach.
Regarding our "revisitation", using Scala 3, we present the existing API generation approach, which is based on deterministic finite automata (DFA), in terms of both the existing states-as-classes encoding of DFAs as APIs, and a new states-as-type-parameters encoding; the latter leverages match types in Scala 3. Regarding our "revision", also using Scala 3, we present a new API generation approach that is based on sets of pomsets instead of DFAs; it crucially leverages match types, too. Our fresh perspective allows us to avoid two forms of combinatorial explosion resulting from implementing concurrent subprotocols in the DFA-based approach. We implement our approach in a new API generation tool.Funding G. Cledou and J. Proença: European Regional Development Fund (ERDF), Operational
Programme for Competitiveness and Internationalisation (COMPETE 2020): POCI-01-0145-FEDER029946 (DaVinci). S. Jongmans: Netherlands Organisation of Scientific Research: 016.Veni.192.103.
J. Proença: Fundação para a Ciência e a Tecnologia (FCT), within the CISTER Research Unit:
UIDP/UIDB/04234/2020. ERDF and FCT, Portugal 2020 Partnership Agreement, Norte Portugal
Regional Operational Programme (NORTE 2020): NORTE-01-0145-FEDER-028550 (REASSURE).
ECSEL Joint Undertaking (JU): grant agreement No 876852 (VALU3S).info:eu-repo/semantics/publishedVersio
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