11,205 research outputs found
Behavioral types in programming languages
A recent trend in programming language research is to use behav- ioral type theory to ensure various correctness properties of large- scale, communication-intensive systems. Behavioral types encompass concepts such as interfaces, communication protocols, contracts, and choreography. The successful application of behavioral types requires a solid understanding of several practical aspects, from their represen- tation in a concrete programming language, to their integration with other programming constructs such as methods and functions, to de- sign and monitoring methodologies that take behaviors into account. This survey provides an overview of the state of the art of these aspects, which we summarize as the pragmatics of behavioral types
Parameterized Concurrent Multi-Party Session Types
Session types have been proposed as a means of statically verifying
implementations of communication protocols. Although prior work has been
successful in verifying some classes of protocols, it does not cope well with
parameterized, multi-actor scenarios with inherent asynchrony. For example, the
sliding window protocol is inexpressible in previously proposed session type
systems. This paper describes System-A, a new typing language which overcomes
many of the expressiveness limitations of prior work. System-A explicitly
supports asynchrony and parallelism, as well as multiple forms of
parameterization. We define System-A and show how it can be used for the static
verification of a large class of asynchronous communication protocols.Comment: In Proceedings FOCLASA 2012, arXiv:1208.432
A Graphical Approach to Progress for Structured Communication in Web Services
We investigate a graphical representation of session invocation
interdependency in order to prove progress for the pi-calculus with sessions
under the usual session typing discipline. We show that those processes whose
associated dependency graph is acyclic can be brought to reduce. We call such
processes transparent processes. Additionally, we prove that for well-typed
processes where services contain no free names, such acyclicity is preserved by
the reduction semantics.
Our results encompass programs (processes containing neither free nor
restricted session channels) and higher-order sessions (delegation).
Furthermore, we give examples suggesting that transparent processes constitute
a large enough class of processes with progress to have applications in modern
session-based programming languages for web services.Comment: In Proceedings ICE 2010, arXiv:1010.530
Typechecking protocols with Mungo and StMungo: a session type toolchain for Java
Static typechecking is an important feature of many standard programming languages. However, static typing focuses on data rather than communication, and therefore does not help programmers correctly implement communication protocols in distributed systems. The theory of session types provides a basis for tackling this problem; we use it to develop two tools that support static typechecking of communication protocols in Java. The first tool, Mungo, extends Java with typestate definitions, which allow classes to be associated with state machines defining permitted sequences of method calls: for example, communication methods. The second tool, StMungo, takes a session type describing a communication protocol, and generates a typestate specification of the permitted sequences of messages in the protocol. Protocol implementations can be validated by Mungo against their typestate definitions and then compiled with a standard Java compiler. The result is a toolchain for static typechecking of communication protocols in Java. We formalise and prove soundness of the typestate inference system used by Mungo, and show that our toolchain can be used to typecheck a client for the standard Simple Mail Transfer Protocol (SMTP)
Session Types in Concurrent Calculi: Higher-Order Processes and Objects
This dissertation investigates different formalisms, in the form of programming language calculi,
that are aimed at providing a theoretical foundation for structured concurrent programming based
on session types. The structure of a session type is essentially a process-algebraic style description
of the behaviour of a single program identifier serving as a communication medium (and usually
referred to as a channel): the types incorporate typed inputs, outputs, and choices which can be
composed to form larger protocol descriptions. The effectiveness of session typing can be attributed
to the linear treatment of channels and session types, and to the use of tractable methods
such as syntactic duality to decide if the types of two connected channels are compatible. Linearity
is ensured when accumulating the uses of a channel into a composite type that describes also
the order of those actions. Duality provides a tractable and intuitive method for deciding when
two connected channels can interact and exchange values in a statically determined type-safe way.
We present our contributions to the theory of sessions, distilled into two families of programming
calculi, the first based on higher-order processes and the second based on objects. Our work unifies,
improves and extends, in manifold ways, the session primitives and typing systems for the
Lambda-calculus, the Pi-calculus, the Object-calculus, and their combinations in multi-paradigm
languages. Of particular interest are: the treatment of infinite interactions expressed with recursive
sessions; the capacity to encapsulate channels in higher-order structures which can be exchanged
and kept suspended, i.e., the use of code as data; the integration of protocol structure directly
into the description of objects, providing a powerful and uniformly extensible set of implementation
abstractions; finally, the introduction of asynchronous subtyping, which enables controlled
reordering of actions on either side of a session. Our work on higher-order processes and on object
calculi for session-based concurrent programming provides a theoretical foundation for programming
language design integrating functional, process, and object-oriented features
PLACES'10: The 3rd Workshop on Programmng Language Approaches to concurrency and Communication-Centric Software
Paphos, Cyprus. March 201
Combining behavioural types with security analysis
Today's software systems are highly distributed and interconnected, and they
increasingly rely on communication to achieve their goals; due to their
societal importance, security and trustworthiness are crucial aspects for the
correctness of these systems. Behavioural types, which extend data types by
describing also the structured behaviour of programs, are a widely studied
approach to the enforcement of correctness properties in communicating systems.
This paper offers a unified overview of proposals based on behavioural types
which are aimed at the analysis of security properties
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
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