A Java typestate checker supporting inheritance

Detecting programming errors in software is increasingly important, and building tools that help developers with this task is a crucial area of investigation on which the industry depends. Leveraging on the observation that in Object-Oriented Programming (OOP) it is natural to define stateful objects where the safe use of methods depends on their internal state, we present Java Typestate Checker (JATYC), a tool that verifies Java source code with respect to typestates. A typestate defines the object’s states, the methods that can be called in each state, and the states resulting from the calls. The tool statically verifies that when a Java program runs: sequences of method calls obey to object’s protocols; objects’ protocols are completed; null-pointer exceptions are not raised; subclasses’ instances respect the protocol of their superclasses. To the best of our knowledge, this is the first OOP tool that simultaneously tackles all these aspects

141 Unsupervised Learning of Non-Uniform Segmental Units for Acoustic Modeling in Speech Recognition

Great progress has been made in the development of recognition systems for continuous read speech but the performance of these systems degrades severely when they are applied to spontaneous speech. This indicates that a different approach in modeling is required to design a system that is better suited to spontaneous speech. Our approach is to combine two advances proposed in previous work: the use of acoustically derive

A Session Subtyping Tool

Session types are becoming popular and have been integrated in several mainstream programming languages. Nevertheless, while many programming languages consider asynchronous fifo channel communication, the notion of subtyping used in session type implementations is the one defined by Gay and Hole for synchronous communication. This might be because there are several notions of asynchronous session subtyping, these notions are usually undecidable, and only recently sound (but not complete) algorithmic characterizations for these subtypings have been proposed. But the fact that the definition of asynchronous session subtyping and the theory behind related algorithms are not easily accessible to non-experts may also prevent further integration. The aim of this paper, and of the tool presented therein, is to make the growing body of knowledge about asynchronous session subtyping more accessible, thus promoting its integration in practical applications of session types

Microservice Dynamic Architecture-Level Deployment Orchestration

We develop a novel approach for run-time global adaptation of microservice applications, based on synthesis of architecture-level reconfiguration orchestrations. More precisely, we devise an algorithm for automatic reconfiguration that reaches a target system Maximum Computational Load by performing optimal deployment orchestrations. To conceive and simulate our approach, we introduce a novel integrated timed architectural modeling/execution language based on an extension of the actor-based object-oriented Abstract Behavioral Specification (ABS) language. In particular, we realize a timed extension of SmartDeployer, whose ABS code annotations make it possible to express architectural properties. Our Timed SmartDeployer tool fully integrates time features of ABS and architectural annotations by generating timed deployment orchestrations. We evaluate the applicability of our approach on a realistic microservice application taken from the literature: an Email Pipeline Processing System. We prove its effectiveness by simulating such an application and by comparing architecture-level reconfiguration with traditional local scaling techniques (which detect scaling needs and enact replications at the level of single microservices). Our comparison results show that our approach avoids cascading slowdowns and consequent increased message loss and latency, which affect traditional local scaling