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António Ravara

Publications and source records attributed to António Ravara.

23 records · Page 2Linked to original sources
arXiv2015

Unlocking Blocked Communicating Processes

We study the problem of disentangling locked processes via code refactoring. We identify and characterise a class of processes that is not lock-free; then we formalise an algorithm that statically detects potential locks and propose refactoring procedures that disentangle detected locks. Our development is cast within a simple setting of a finite linear CCS variant â although it suffices to illustrate the main concepts, we also discuss how our work extends to other language extensions.

cs.PL↗
arXiv2014

Proceedings 10th International Workshop on Automated Specification and Verification of Web Systems

These proceedings contain the papers presented at the 10th International Workshop on Automated Specification and Verification of Web Systems (WWV 2014), which was held on 18 July 2014 in Vienna, Austria, as a satellite workshop of the Federated Logic Conference (FLoC 2014), associated to the 7th International Joint Conference on Automated Reasoning (IJCAR 2014), as part of the Vienna Summer of Logic (VSL 2014). WWV is a yearly workshop that aims at providing an interdisciplinary forum to facilitate the cross-fertilization and the advancement of hybrid methods that exploit concepts and tools drawn from rule-based programming, formal methods, software engineering and Web-oriented research.

cs.LO↗
arXiv2014

Session Types as Generic Process Types

Behavioural type systems ensure more than the usual safety guarantees of static analysis. They are based on the idea of "types-as-processes", providing dedicated type algebras for particular properties, ranging from protocol compatibility to race-freedom, lock-freedom, or even responsiveness. Two successful, although rather different, approaches, are session types and process types. The former allows to specify and verify (distributed) communication protocols using specific type (proof) systems; the latter allows to infer from a system specification a process abstraction on which it is simpler to verify properties, using a generic type (proof) system. What is the relationship between these approaches? Can the generic one subsume the specific one? At what price? And can the former be used as a compiler for the latter? The work presented herein is a step towards answers to such questions. Concretely, we define a stepwise encoding of a pi-calculus with sessions and session types (the system of Gay and Hole) into a pi-calculus with process types (the Generic Type System of Igarashi and Kobayashi). We encode session type environments, polarities (which distinguish session channels end-points), and labelled sums. We show forward and reverse operational correspondences for the encodings, as well as typing correspondences. To faithfully encode session subtyping in process types subtyping, one needs to add to the target language record constructors and new subtyping rules. In conclusion, the programming convenience of session types as protocol abstractions can be combined with the simplicity and power of the pi-calculus, taking advantage in particular of the framework provided by the Generic Type System.

cs.PL↗
arXiv2012

Proceedings 11th International Workshop on Foundations of Coordination Languages and Self Adaptation

Welcome to the proceedings of FOCLASA 2012, the 11th International Workshop on the Foundations of Coordination Languages and Self-Adaptation. FOCLASA 2012 was held in Newcastle upon Tyne, UK, on September 8, 2012 as a satellite event of CONCUR 2012, the 23rd International Conference on Concurrency Theory. The workshop provides a venue where researchers and practitioners could meet, exchange ideas, identify common problems, determine some of the key and fundamental issues related to coordination languages and self adaptation, and explore together and disseminate solutions. Indeed, a number of hot research topics are currently sharing the common problem of combining concurrent, distributed, mobile and heterogeneous components, trying to harness the intrinsic complexity of the resulting systems. Computation nowadays is becoming inherently concurrent, either because of characteristics of the hardware (with multicore processors becoming omnipresent) or due to the ubiquitous presence of distributed systems (incarnated in the Internet). Computational systems are therefore typically distributed, concurrent, mobile, and often involve composition of heterogeneous components. To specify and reason about such systems and go beyond the functional correctness proofs, e.g., by supporting reusability and improving maintainability, approaches such as coordination languages and self adaptation are recognised as fundamental. This year, we received 13 submissions involving 35 authors from 10 different countries. Papers underwent a rigorous review process, and all accepted papers received 3 review reports. After the review process, the international Program Committee of FOCLASA 2012 decided to select 8 papers for presentation during the workshop and inclusion in these proceedings. These papers tackle different issues that are currently central to our community, self-adaptation and coordination, processes and coordination, and type systems. The workshop features an invited talk by Sebastian Uchitel from Imperial College London (UK).

cs.DC↗