P. Degano, G. Ferrari, Letterio Galletta, Gianluca Mezzetti
Context Oriented Programming (COP) concerns the ability of programs to adapt to changes in their running environment. A number of programming languages endowed with COP constructs and features have been developed. However, some foundational issues remain unclear. This paper proposes adopting static analysis techniques to reason on and predict how programs adapt their behaviour. We introduce a core functional language, ContextML, equipped with COP primitives for manipulating contexts and for programming behavioural variations. In particular, we specify the dispatching mechanism, used to select the program fragments to be executed in the current active context. Besides the dynamic semantics we present an annotated type system. It guarantees that the well-typed programs adapt to any context, i.e. the dispatching mechanism always succeeds at run-time.
{"title":"Typing Context-Dependent Behavioural Variation","authors":"P. Degano, G. Ferrari, Letterio Galletta, Gianluca Mezzetti","doi":"10.4204/EPTCS.109.5","DOIUrl":"https://doi.org/10.4204/EPTCS.109.5","url":null,"abstract":"Context Oriented Programming (COP) concerns the ability of programs to adapt to changes in their running environment. A number of programming languages endowed with COP constructs and features have been developed. However, some foundational issues remain unclear. This paper proposes adopting static analysis techniques to reason on and predict how programs adapt their behaviour. We introduce a core functional language, ContextML, equipped with COP primitives for manipulating contexts and for programming behavioural variations. In particular, we specify the dispatching mechanism, used to select the program fragments to be executed in the current active context. Besides the dynamic semantics we present an annotated type system. It guarantees that the well-typed programs adapt to any context, i.e. the dispatching mechanism always succeeds at run-time.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"38 11 1","pages":"28-33"},"PeriodicalIF":0.0,"publicationDate":"2013-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75862254","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}
Massimo Bartoletti, Tiziana Cimoli, G. Pinna, R. Zunino
We introduce a basic model for contracts. Our model extends event structures with a new relation, which faithfully captures the circular dependencies among contract clauses. We establish whether an agreement exists which respects all the contracts at hand (i.e. all the dependencies can be resolved), and we detect the obligations of each participant. The main technical contribution is a correspondence between our model and a fragment of the contract logic PCL. More precisely, we show that the reachable events are exactly those which correspond to provable atoms in the logic. Despite of this strong correspondence, our model improves previous work on PCL by exhibiting a finer-grained notion of culpability, which takes into account the legitimate orderings of events.
{"title":"An event-based model for contracts","authors":"Massimo Bartoletti, Tiziana Cimoli, G. Pinna, R. Zunino","doi":"10.4204/EPTCS.109.3","DOIUrl":"https://doi.org/10.4204/EPTCS.109.3","url":null,"abstract":"We introduce a basic model for contracts. Our model extends event structures with a new relation, which faithfully captures the circular dependencies among contract clauses. We establish whether an agreement exists which respects all the contracts at hand (i.e. all the dependencies can be resolved), and we detect the obligations of each participant. The main technical contribution is a correspondence between our model and a fragment of the contract logic PCL. More precisely, we show that the reachable events are exactly those which correspond to provable atoms in the logic. Despite of this strong correspondence, our model improves previous work on PCL by exhibiting a finer-grained notion of culpability, which takes into account the legitimate orderings of events.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"49 1","pages":"13-20"},"PeriodicalIF":0.0,"publicationDate":"2013-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81122760","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 describes an operational semantics for futures, with the primary target on energy efficiency. The work in progress is built around an insight that different threads can coordinate by running at different "paces," so that the time for synchronization and the resulting wasteful energy consumption can be reduced. We exploit several inherent characteristics of futures to determine how the paces of involving threads can be coordinated. The semantics is inspired by recent advances in computer architectures, where the frequencies of CPU cores can be adjusted dynamically. The work is a first-step toward a direction where variant frequencies are directly modeled as an essential semantic feature in concurrent programming languages.
{"title":"Variant-Frequency Semantics for Green Futures","authors":"Yu David Liu","doi":"10.4204/EPTCS.109.1","DOIUrl":"https://doi.org/10.4204/EPTCS.109.1","url":null,"abstract":"This paper describes an operational semantics for futures, with the primary target on energy efficiency. The work in progress is built around an insight that different threads can coordinate by running at different \"paces,\" so that the time for synchronization and the resulting wasteful energy consumption can be reduced. We exploit several inherent characteristics of futures to determine how the paces of involving threads can be coordinated. The semantics is inspired by recent advances in computer architectures, where the frequencies of CPU cores can be adjusted dynamically. The work is a first-step toward a direction where variant frequencies are directly modeled as an essential semantic feature in concurrent programming languages.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"30 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86715110","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}
As modern architectures introduce additional heterogeneity and parallelism, we look for ways to deal with this that do not involve specialising software to every platform. In this paper, we take the Join Calculus, an elegant model for concurrent computation, and show how it can be mapped to an architecture by a Cartesian-product-style construction, thereby making use of the calculus' inherent non-determinism to encode placement choices. This unifies the concepts of placement and scheduling into a single task.
{"title":"Mapping the Join Calculus to Heterogeneous Hardware","authors":"Peter Calvert, A. Mycroft","doi":"10.4204/EPTCS.109.2","DOIUrl":"https://doi.org/10.4204/EPTCS.109.2","url":null,"abstract":"As modern architectures introduce additional heterogeneity and parallelism, we look for ways to deal with this that do not involve specialising software to every platform. In this paper, we take the Join Calculus, an elegant model for concurrent computation, and show how it can be mapped to an architecture by a Cartesian-product-style construction, thereby making use of the calculus' inherent non-determinism to encode placement choices. This unifies the concepts of placement and scheduling into a single task.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"65 10","pages":"7-12"},"PeriodicalIF":0.0,"publicationDate":"2013-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72449178","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}
Choreography-based programming is a powerful paradigm for defining communication-based systems from a global viewpoint. A choreography can be checked against multiparty protocol specifications, given as behavioural types, that may be instantiated indefinitely at runtime. Each protocol instance is started with a synchronisation among the involved peers. We analyse a simple transformation from a choreography with a possibly unbounded number of protocol instantiations to a choreography instantiating a single protocol, which is the merge of the original ones. This gives an effective methodology for obtaining new protocols by composing existing ones. Moreover, by removing all synchronisations required for starting protocol instances, our transformation reduces the number of communications and resources needed to execute a choreography.
{"title":"Merging Multiparty Protocols in Multiparty Choreographies","authors":"Marco Carbone, F. Montesi","doi":"10.4204/EPTCS.109.4","DOIUrl":"https://doi.org/10.4204/EPTCS.109.4","url":null,"abstract":"Choreography-based programming is a powerful paradigm for defining communication-based systems from a global viewpoint. A choreography can be checked against multiparty protocol specifications, given as behavioural types, that may be instantiated indefinitely at runtime. Each protocol instance is started with a synchronisation among the involved peers. \u0000We analyse a simple transformation from a choreography with a possibly unbounded number of protocol instantiations to a choreography instantiating a single protocol, which is the merge of the original ones. This gives an effective methodology for obtaining new protocols by composing existing ones. Moreover, by removing all synchronisations required for starting protocol instances, our transformation reduces the number of communications and resources needed to execute a choreography.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"35 1","pages":"21-27"},"PeriodicalIF":0.0,"publicationDate":"2013-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88504737","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 present Dynamic Condition Response Graphs (DCR Graphs) as a declarative, event-based process model inspired by the workflow language employed by our industrial partner and conservatively generalizing prime event structures. A dynamic condition response graph is a directed graph with nodes representing the events that can happen and arrows representing four relations between events: condition, response, include, and exclude. Distributed DCR Graphs is then obtained by assigning roles to events and principals. We give a graphical notation inspired by related work by van der Aalst et al. We exemplify the use of distributed DCR Graphs on a simple workflow taken from a field study at a Danish hospital, pointing out their flexibility compared to imperative workflow models. Finally we provide a mapping from DCR Graphs to Buchi-automata.
我们将动态条件响应图(DCR图)作为一种声明性的、基于事件的过程模型，其灵感来自于我们的工业合作伙伴使用的工作流语言，并保守地概括了主要事件结构。动态条件响应图是一个有向图，其中节点表示可能发生的事件，箭头表示事件之间的四种关系:条件、响应、包括和排除。然后通过为事件和主体分配角色来获得分布式DCR图。我们从van der Aalst等人的相关工作中得到启发，给出了一个图形符号。我们举例说明了分布式DCR图在丹麦一家医院的一个简单工作流上的使用，指出了它们与命令式工作流模型相比的灵活性。最后给出了从DCR图到布吉自动机的映射。
{"title":"Declarative Event-Based Workflow as Distributed Dynamic Condition Response Graphs","authors":"Thomas T. Hildebrandt, R. Mukkamala","doi":"10.4204/EPTCS.69.5","DOIUrl":"https://doi.org/10.4204/EPTCS.69.5","url":null,"abstract":"We present Dynamic Condition Response Graphs (DCR Graphs) as a declarative, event-based process model inspired by the workflow language employed by our industrial partner and conservatively generalizing prime event structures. A dynamic condition response graph is a directed graph with nodes representing the events that can happen and arrows representing four relations between events: condition, response, include, and exclude. Distributed DCR Graphs is then obtained by assigning roles to events and principals. We give a graphical notation inspired by related work by van der Aalst et al. We exemplify the use of distributed DCR Graphs on a simple workflow taken from a field study at a Danish hospital, pointing out their flexibility compared to imperative workflow models. Finally we provide a mapping from DCR Graphs to Buchi-automata.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"25 1","pages":"59-73"},"PeriodicalIF":0.0,"publicationDate":"2011-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74566725","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}
Nuno Alves, Raymond Hu, N. Yoshida, Pierre-Malo Deniélou
The development of the SJ Framework for session-based distributed programming is part of recent and ongoing research into integrating session types and practical, real-world programming languages. SJ programs featuring session types (protocols) are statically checked by the SJ compiler to verify the key property of communication safety, meaning that parties engaged in a session only communicate messages, including higher-order communications via session delegation, that are compatible with the message types expected by the recipient. This paper presents current work on security aspects of the SJ Framework. Firstly, we discuss our implementation experience from improving the SJ Runtime platform with security measures to protect and augment communication safety at runtime. We implement a transport component for secure session execution that uses a modified TLS connection with authentication based on the Secure Remote Password (SRP) protocol. The key technical point is the delicate treatment of secure session delegation to counter a previous vulnerability. We find that the modular design of the SJ Runtime, based on the notion of an Abstract Transport for session communication, supports rapid extension to utilise additional transports whilst separating this concern from the application-level session programming task. In the second part of this abstract, we formally prove the target security properties by modelling the extended SJ delegation protocols in the pi-calculus.
{"title":"Secure Execution of Distributed Session Programs","authors":"Nuno Alves, Raymond Hu, N. Yoshida, Pierre-Malo Deniélou","doi":"10.4204/EPTCS.69.1","DOIUrl":"https://doi.org/10.4204/EPTCS.69.1","url":null,"abstract":"The development of the SJ Framework for session-based distributed programming is part of recent and ongoing research into integrating session types and practical, real-world programming languages. SJ programs featuring session types (protocols) are statically checked by the SJ compiler to verify the key property of communication safety, meaning that parties engaged in a session only communicate messages, including higher-order communications via session delegation, that are compatible with the message types expected by the recipient. \u0000This paper presents current work on security aspects of the SJ Framework. Firstly, we discuss our implementation experience from improving the SJ Runtime platform with security measures to protect and augment communication safety at runtime. We implement a transport component for secure session execution that uses a modified TLS connection with authentication based on the Secure Remote Password (SRP) protocol. The key technical point is the delicate treatment of secure session delegation to counter a previous vulnerability. We find that the modular design of the SJ Runtime, based on the notion of an Abstract Transport for session communication, supports rapid extension to utilise additional transports whilst separating this concern from the application-level session programming task. In the second part of this abstract, we formally prove the target security properties by modelling the extended SJ delegation protocols in the pi-calculus.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"38 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2011-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77214393","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}
Prodromos Gerakios, N. Papaspyrou, Konstantinos Sagonas
Deadlocks occur in concurrent programs as a consequence of cyclic resource acquisition between threads. In this paper we present a novel type system that guarantees deadlock freedom for a language with references, unstructured locking primitives, and locks which are implicitly associated with references. The proposed type system does not impose a strict lock acquisition order and thus increases programming language expressiveness.
{"title":"A Type System for Unstructured Locking that Guarantees Deadlock Freedom without Imposing a Lock Ordering","authors":"Prodromos Gerakios, N. Papaspyrou, Konstantinos Sagonas","doi":"10.4204/EPTCS.69.4","DOIUrl":"https://doi.org/10.4204/EPTCS.69.4","url":null,"abstract":"Deadlocks occur in concurrent programs as a consequence of cyclic resource acquisition between threads. In this paper we present a novel type system that guarantees deadlock freedom for a language with references, unstructured locking primitives, and locks which are implicitly associated with references. The proposed type system does not impose a strict lock acquisition order and thus increases programming language expressiveness.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"66 6 1","pages":"44-58"},"PeriodicalIF":0.0,"publicationDate":"2011-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87755966","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 present an inference system for a version of the Pi-calculus in Haskell for the session type proposed by Honda et al. The session type is very useful in checking if the communications are well-behaved. The full session type implementation in Haskell was first presented by Pucella and Tov, which is 'semi-automatic' in that the manual operations for the type representation was necessary. We give an automatic type inference for the session type by using a more abstract representation for the session type based on the 'de Bruijn levels'. We show an example of the session type inference for a simple SMTP client.
{"title":"Session Type Inference in Haskell","authors":"Keigo Imai, Shoji Yuen, K. Agusa","doi":"10.4204/EPTCS.69.6","DOIUrl":"https://doi.org/10.4204/EPTCS.69.6","url":null,"abstract":"We present an inference system for a version of the Pi-calculus in Haskell for the session type proposed by Honda et al. The session type is very useful in checking if the communications are well-behaved. The full session type implementation in Haskell was first presented by Pucella and Tov, which is 'semi-automatic' in that the manual operations for the type representation was necessary. We give an automatic type inference for the session type by using a more abstract representation for the session type based on the 'de Bruijn levels'. We show an example of the session type inference for a simple SMTP client.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"112 1","pages":"74-91"},"PeriodicalIF":0.0,"publicationDate":"2011-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76568743","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 is often a sort of a protocol associated to each class, stating when and how certain methods should be called. Given that this protocol is, if at all, described in the documentation accompanying the class, current mainstream object-oriented languages cannot provide for the verification of client code adherence against the sought class behaviour. We have defined a class-based concurrent object-oriented language that formalises such protocols in the form of usage types. Usage types are attached to class definitions, allowing for the specification of (1) the available methods, (2) the tests clients must perform on the result of methods, and (3) the object status - linear or shared - all of which depend on the object's state. Our work extends the recent approach on modular session types by eliminating channel operations, and defining the method call as the single communication primitive in both sequential and concurrent settings. In contrast to previous works, we define a single category for objects, instead of distinct categories for linear and for shared objects, and let linear objects evolve into shared ones. We introduce a standard sync qualifier to prevent thread interference in certain operations on shared objects. We formalise the language syntax, the operational semantics, and a type system that enforces by static typing that methods are called only when available, and by a single client if so specified in the usage type. We illustrate the language via a complete example.
{"title":"Channels as Objects in Concurrent Object-Oriented Programming","authors":"Joana Campos, V. Vasconcelos","doi":"10.4204/EPTCS.69.2","DOIUrl":"https://doi.org/10.4204/EPTCS.69.2","url":null,"abstract":"There is often a sort of a protocol associated to each class, stating when and how certain methods should be called. Given that this protocol is, if at all, described in the documentation accompanying the class, current mainstream object-oriented languages cannot provide for the verification of client code adherence against the sought class behaviour. We have defined a class-based concurrent object-oriented language that formalises such protocols in the form of usage types. Usage types are attached to class definitions, allowing for the specification of (1) the available methods, (2) the tests clients must perform on the result of methods, and (3) the object status - linear or shared - all of which depend on the object's state. Our work extends the recent approach on modular session types by eliminating channel operations, and defining the method call as the single communication primitive in both sequential and concurrent settings. In contrast to previous works, we define a single category for objects, instead of distinct categories for linear and for shared objects, and let linear objects evolve into shared ones. We introduce a standard sync qualifier to prevent thread interference in certain operations on shared objects. We formalise the language syntax, the operational semantics, and a type system that enforces by static typing that methods are called only when available, and by a single client if so specified in the usage type. We illustrate the language via a complete example.","PeriodicalId":53164,"journal":{"name":"Journal of Historic Buildings and Places","volume":"17 1","pages":"12-28"},"PeriodicalIF":0.0,"publicationDate":"2011-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88630659","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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