Reversible distributed programs have the ability to abort unproductive computation paths and backtrack, while unwinding communication that occurred in the aborted paths. While it is natural to assume that reversibility implies full state recovery (as with traditional roll-back recovery protocols), an interesting alternative is to separate backtracking from local state recovery. For example, such a model could be used to create complex transactions out of nested compensable transactions where a programmer-supplied compensation defines the work required to "unwind" a transaction. Reversible distributed computing has received considerable theoretical attention, but little reduction to practice; the few published implementations of languages supporting reversibility depend upon a high degree of central control. The objective of this paper is to demonstrate that a practical reversible distributed language can be efficiently implemented in a fully distributed manner. We discuss such a language, supporting CSP-style synchronous communication, embedded in Scala. While this language provided the motivation for the work described in this paper, our focus is upon the distributed implementation. In particular, we demonstrate that a "high-level" semantic model can be implemented using a simple point-to-point protocol.
{"title":"Reversible Communicating Processes","authors":"Geoffrey M. Brown, A. Sabry","doi":"10.4204/EPTCS.203.4","DOIUrl":"https://doi.org/10.4204/EPTCS.203.4","url":null,"abstract":"Reversible distributed programs have the ability to abort unproductive computation paths and backtrack, while unwinding communication that occurred in the aborted paths. While it is natural to assume that reversibility implies full state recovery (as with traditional roll-back recovery protocols), an interesting alternative is to separate backtracking from local state recovery. For example, such a model could be used to create complex transactions out of nested compensable transactions where a programmer-supplied compensation defines the work required to \"unwind\" a transaction. \u0000Reversible distributed computing has received considerable theoretical attention, but little reduction to practice; the few published implementations of languages supporting reversibility depend upon a high degree of central control. The objective of this paper is to demonstrate that a practical reversible distributed language can be efficiently implemented in a fully distributed manner. \u0000We discuss such a language, supporting CSP-style synchronous communication, embedded in Scala. While this language provided the motivation for the work described in this paper, our focus is upon the distributed implementation. In particular, we demonstrate that a \"high-level\" semantic model can be implemented using a simple point-to-point protocol.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"2 1","pages":"45-59"},"PeriodicalIF":0.0,"publicationDate":"2016-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79007499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Distributed software is becoming more and more dynamic to support applications able to respond and adapt to the changes of their execution environment. For instance, service-oriented computing (SOC) envisages applications as services running over globally available computational resources where discovery and binding between them is transparently performed by a middleware. Asynchronous Relational Networks (ARNs) is a well-known formal orchestration model, based on hypergraphs, for the description of service-oriented software artefacts. Choreography and orchestration are the two main design principles for the development of distributed software. In this work, we propose Communicating Relational Networks (CRNs), which is a variant of ARNs, but relies on choreographies for the characterisation of the communicational aspects of a software artefact, and for making their automated analysis more efficient.
{"title":"Communicating machines as a dynamic binding mechanism of services","authors":"Ignacio Vissani, C. L. Pombo, E. Tuosto","doi":"10.4204/EPTCS.203.7","DOIUrl":"https://doi.org/10.4204/EPTCS.203.7","url":null,"abstract":"Distributed software is becoming more and more dynamic to support applications able to respond and adapt to the changes of their execution environment. For instance, service-oriented computing (SOC) envisages applications as services running over globally available computational resources where discovery and binding between them is transparently performed by a middleware. Asynchronous Relational Networks (ARNs) is a well-known formal orchestration model, based on hypergraphs, for the description of service-oriented software artefacts. Choreography and orchestration are the two main design principles for the development of distributed software. In this work, we propose Communicating Relational Networks (CRNs), which is a variant of ARNs, but relies on choreographies for the characterisation of the communicational aspects of a software artefact, and for making their automated analysis more efficient.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"21 1","pages":"85-98"},"PeriodicalIF":0.0,"publicationDate":"2016-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74349252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Side effects are a core part of practical programming. However, they are often hard to reason about, particularly in a concurrent setting. We propose a foundation for reasoning about concurrent side effects using sessions. Primarily, we show that session types are expressive enough to encode an effect system for stateful processes. This is formalised via an effect-preserving encoding of a simple imperative language with an effect system into the pi-calculus with session primitives and session types (into which we encode effect specifications). This result goes towards showing a connection between the expressivity of session types and effect systems. We briefly discuss how the encoding could be extended and applied to reason about and control concurrent side effects.
{"title":"Using session types as an effect system","authors":"Dominic A. Orchard, N. Yoshida","doi":"10.4204/EPTCS.203.1","DOIUrl":"https://doi.org/10.4204/EPTCS.203.1","url":null,"abstract":"Side effects are a core part of practical programming. However, they are often hard to reason about, particularly in a concurrent setting. We propose a foundation for reasoning about concurrent side effects using sessions. Primarily, we show that session types are expressive enough to encode an effect system for stateful processes. This is formalised via an effect-preserving encoding of a simple imperative language with an effect system into the pi-calculus with session primitives and session types (into which we encode effect specifications). This result goes towards showing a connection between the expressivity of session types and effect systems. We briefly discuss how the encoding could be extended and applied to reason about and control concurrent side effects.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"45 1","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2016-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78921831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, Wadler presented a continuation-passing translation from a session-typed functional language, GV, to a process calculus based on classical linear logic, CP. However, this translation is one-way: CP is more expressive than GV. We propose an extension of GV, called HGV, and give translations showing that it is as expressive as CP. The new translations shed light both on the original translation from GV to CP, and on the limitations in expressiveness of GV.
{"title":"Sessions as Propositions","authors":"S. Lindley, J. Garrett Morris","doi":"10.4204/EPTCS.155.2","DOIUrl":"https://doi.org/10.4204/EPTCS.155.2","url":null,"abstract":"Recently, Wadler presented a continuation-passing translation from a session-typed functional language, GV, to a process calculus based on classical linear logic, CP. However, this translation is one-way: CP is more expressive than GV. We propose an extension of GV, called HGV, and give translations showing that it is as expressive as CP. The new translations shed light both on the original translation from GV to CP, and on the limitations in expressiveness of GV.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"7 2 1","pages":"9-16"},"PeriodicalIF":0.0,"publicationDate":"2014-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77515730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We interpret Linear Logic Proof Nets in a term language based on Solos calculus. The system includes a synchronisation mechanism, obtained by a conservative extension of the logic, that enables to define non-deterministic behaviours and multiparty sessions.
{"title":"Multiparty Sessions based on Proof Nets","authors":"D. Mostrous","doi":"10.4204/EPTCS.155.1","DOIUrl":"https://doi.org/10.4204/EPTCS.155.1","url":null,"abstract":"We interpret Linear Logic Proof Nets in a term language based on Solos calculus. The system includes a synchronisation mechanism, obtained by a conservative extension of the logic, that enables to define non-deterministic behaviours and multiparty sessions.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"26 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2014-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75099779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Concurrent systems, i.e., systems of parallel processes, are nearly ubiquitous and verifying the correctness of such systems is becoming an important subject. Many formalisms were invented for such purpose, however, new types of systems are introduced and there is a need for handling larger systems. One examples is wireless sensor networks that are being deployed in increasing numbers in various areas; and in particular safety-critical areas, e.g., bush fire detection. Thus, ensuring their correctness is important.A process calculus is a formal language for modeling concurrent systems. The pi-calculus is a prominent example of such a language featuring message-passing concurrency. Psi-calculi is a parametric framework that extends the pi-calculus with arbitrary data and logics. Psi-calculi feature a universal theory with its results checked in an automated theorem prover ensuring their correctness.In this thesis, we extend psi-calculi expressiveness and modeling precision by introducing a sort system and generalised pattern matching. We show that the extended psi-calculi enjoy the same meta-theoretical results.We have developed the Pwb, a tool for the psi-calculi framework. The tool provides a high-level interactive symbolic execution and automated behavioral equivalence checking. We exemplify the use of the tool by developing a high-level executable model of a data collection protocol for wireless sensor networks.We are the first to introduce a session types based system for systems with unreliable communication. Remarkably, we do not need to add specific extensions to the types to accommodate such systems. We prove the standard desirable properties for type systems hold also for our type system.
{"title":"Session Types for Broadcasting","authors":"Dimitrios Kouzapas, Ramunas Gutkovas, S. Gay","doi":"10.4204/EPTCS.155.4","DOIUrl":"https://doi.org/10.4204/EPTCS.155.4","url":null,"abstract":"Concurrent systems, i.e., systems of parallel processes, are nearly ubiquitous and verifying the correctness of such systems is becoming an important subject. Many formalisms were invented for such purpose, however, new types of systems are introduced and there is a need for handling larger systems. One examples is wireless sensor networks that are being deployed in increasing numbers in various areas; and in particular safety-critical areas, e.g., bush fire detection. Thus, ensuring their correctness is important.A process calculus is a formal language for modeling concurrent systems. The pi-calculus is a prominent example of such a language featuring message-passing concurrency. Psi-calculi is a parametric framework that extends the pi-calculus with arbitrary data and logics. Psi-calculi feature a universal theory with its results checked in an automated theorem prover ensuring their correctness.In this thesis, we extend psi-calculi expressiveness and modeling precision by introducing a sort system and generalised pattern matching. We show that the extended psi-calculi enjoy the same meta-theoretical results.We have developed the Pwb, a tool for the psi-calculi framework. The tool provides a high-level interactive symbolic execution and automated behavioral equivalence checking. We exemplify the use of the tool by developing a high-level executable model of a data collection protocol for wireless sensor networks.We are the first to introduce a session types based system for systems with unreliable communication. Remarkably, we do not need to add specific extensions to the types to accommodate such systems. We prove the standard desirable properties for type systems hold also for our type system.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"284 1","pages":"25-31"},"PeriodicalIF":0.0,"publicationDate":"2014-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73400430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, we incorporate reversibility into structured communication-based programming, to allow parties of a session to automatically undo, in a rollback fashion, the effect of previously executed interactions. This permits taking different computation paths along the same session, as well as reverting the whole session and starting a new one. Our aim is to define a theoretical basis for examining the interplay in concurrent systems between reversible computation and session-based interaction. We thus enrich a session-based variant of pi-calculus with memory devices, dedicated to keep track of the computation history of sessions in order to reverse it. We discuss our initial investigation concerning the definition of a session type discipline for the proposed reversible calculus, and its practical advantages for static verification of safe composition in communication-centric distributed software performing reversible computations.
{"title":"Towards Reversible Sessions","authors":"F. Tiezzi, N. Yoshida","doi":"10.4204/EPTCS.155.3","DOIUrl":"https://doi.org/10.4204/EPTCS.155.3","url":null,"abstract":"In this work, we incorporate reversibility into structured communication-based programming, to allow parties of a session to automatically undo, in a rollback fashion, the effect of previously executed interactions. This permits taking different computation paths along the same session, as well as reverting the whole session and starting a new one. Our aim is to define a theoretical basis for examining the interplay in concurrent systems between reversible computation and session-based interaction. We thus enrich a session-based variant of pi-calculus with memory devices, dedicated to keep track of the computation history of sessions in order to reverse it. We discuss our initial investigation concerning the definition of a session type discipline for the proposed reversible calculus, and its practical advantages for static verification of safe composition in communication-centric distributed software performing reversible computations.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"40 1","pages":"17-24"},"PeriodicalIF":0.0,"publicationDate":"2014-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81152650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Janwillem Swalens, Stefan Marr, Joeri De Koster, T. V. Cutsem
In the past decades, many different programming models for managing concurrency in applications have been proposed, such as the actor model, Communicating Sequential Processes, and Software Transactional Memory. The ubiquity of multi-core processors has made harnessing concurrency even more important. We observe that modern languages, such as Scala, Clojure, or F#, provide not one, but multiple concurrency models that help developers manage concurrency. Large end-user applications are rarely built using just a single concurrency model. Programmers need to manage a responsive UI, deal with file or network I/O, asynchronous workflows, and shared resources. Different concurrency models facilitate different requirements. This raises the issue of how these concurrency models interact, and whether they are composable. After all, combining different concurrency models may lead to subtle bugs or inconsistencies. In this paper, we perform an in-depth study of the concurrency abstractions provided by the Clojure language. We study all pairwise combinations of the abstractions, noting which ones compose without issues, and which do not. We make an attempt to abstract from the specifics of Clojure, identifying the general properties of concurrency models that facilitate or hinder composition.
{"title":"Towards Composable Concurrency Abstractions","authors":"Janwillem Swalens, Stefan Marr, Joeri De Koster, T. V. Cutsem","doi":"10.4204/EPTCS.155.8","DOIUrl":"https://doi.org/10.4204/EPTCS.155.8","url":null,"abstract":"In the past decades, many different programming models for managing concurrency in applications have been proposed, such as the actor model, Communicating Sequential Processes, and Software Transactional Memory. The ubiquity of multi-core processors has made harnessing concurrency even more important. We observe that modern languages, such as Scala, Clojure, or F#, provide not one, but multiple concurrency models that help developers manage concurrency. Large end-user applications are rarely built using just a single concurrency model. Programmers need to manage a responsive UI, deal with file or network I/O, asynchronous workflows, and shared resources. Different concurrency models facilitate different requirements. This raises the issue of how these concurrency models interact, and whether they are composable. After all, combining different concurrency models may lead to subtle bugs or inconsistencies. \u0000In this paper, we perform an in-depth study of the concurrency abstractions provided by the Clojure language. We study all pairwise combinations of the abstractions, noting which ones compose without issues, and which do not. We make an attempt to abstract from the specifics of Clojure, identifying the general properties of concurrency models that facilitate or hinder composition.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"21 1","pages":"54-60"},"PeriodicalIF":0.0,"publicationDate":"2014-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82219862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There has been a considerable amount of work on retrieving functions in function libraries using their type as search key. The availability of rich component specifications, in the form of behavioral types, enables similar queries where one can search a component library using the behavioral type of a component as the search key. Just like for function libraries, however, component libraries will contain components whose type differs from the searched one in the order of messages or in the position of the branching points. Thus, it makes sense to also look for those components whose type is different from, but isomorphic to, the searched one. In this article we give semantic and axiomatic characterizations of isomorphic session types. The theory of session type isomorphisms turns out to be subtle. In part this is due to the fact that it relies on a non-standard notion of equivalence between processes. In addition, we do not know whether the axiomatization is complete. It is known that the isomorphisms for arrow, product and sum types are not finitely axiomatisable, but it is not clear yet whether this negative results holds also for the family of types we consider in this work.
{"title":"Session Type Isomorphisms","authors":"M. Dezani-Ciancaglini, L. Padovani, J. Pantović","doi":"10.4204/EPTCS.155.9","DOIUrl":"https://doi.org/10.4204/EPTCS.155.9","url":null,"abstract":"There has been a considerable amount of work on retrieving functions in function libraries using their type as search key. The availability of rich component specifications, in the form of behavioral types, enables similar queries where one can search a component library using the behavioral type of a component as the search key. Just like for function libraries, however, component libraries will contain components whose type differs from the searched one in the order of messages or in the position of the branching points. Thus, it makes sense to also look for those components whose type is different from, but isomorphic to, the searched one. \u0000In this article we give semantic and axiomatic characterizations of isomorphic session types. The theory of session type isomorphisms turns out to be subtle. In part this is due to the fact that it relies on a non-standard notion of equivalence between processes. In addition, we do not know whether the axiomatization is complete. It is known that the isomorphisms for arrow, product and sum types are not finitely axiomatisable, but it is not clear yet whether this negative results holds also for the family of types we consider in this work.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"2009 1","pages":"61-71"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86268385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes a technique to specify and verify whether a loop can be parallelised. Our approach can be used as an additional step in a parallelising compiler to verify user annotations about loop dependences. Essentially, our technique requires each loop iteration to be specified with the locations it will read and write. From the loop iteration specifications, the loop (in)dependences can be derived. Moreover, the loop iteration specifications also reveal where synchronisation is needed in the parallelised program. The loop iteration specifications can be verified using permission-based separation logic.
{"title":"Verifying Parallel Loops with Separation Logic","authors":"S. Blom, Saeed Darabi, M. Huisman","doi":"10.4204/EPTCS.155.7","DOIUrl":"https://doi.org/10.4204/EPTCS.155.7","url":null,"abstract":"This paper proposes a technique to specify and verify whether a loop can be parallelised. Our approach can be used as an additional step in a parallelising compiler to verify user annotations about loop dependences. Essentially, our technique requires each loop iteration to be specified with the locations it will read and write. From the loop iteration specifications, the loop (in)dependences can be derived. Moreover, the loop iteration specifications also reveal where synchronisation is needed in the parallelised program. The loop iteration specifications can be verified using permission-based separation logic.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"18 1","pages":"47-53"},"PeriodicalIF":0.0,"publicationDate":"2014-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77152435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"历史学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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