Zoltán Micskei

The many meanings of UML 2 Sequence Diagrams: a survey

Scenario languages are widely used in software development. Typical usage scenarios, forbidden behaviors, test cases, and many more aspects can be depicted with graphical scenarios. Scenario languages were introduced into the Unified Modeling Language (UML) under the name of Sequence Diagrams. The 2.0 version of UML changed Sequence Diagrams significantly and the expressiveness of the language was highly increased. However, the complexity of the language (and the diversity of the goals Sequence Diagrams are used for) yields several possible choices in its semantics. This paper collects and categorizes the semantic choices in the language, surveys the formal semantics proposed for Sequence Diagrams, and presents how these approaches handle the various semantic choices.

A concept for testing robustness and safety of the context-aware behaviour of autonomous systems

Autonomous systems are used nowadays in more and more sectors from vehicles to domestic robots. They can make decisions on their own or interact with humans, thus their robustness and safety are properties of crucial importance. Due to the adaptive and context-aware nature of these systems, the testing of such properties is especially challenging. In this paper, we propose a model-based testing approach to capture the context and requirements of such systems, to automatically generate test data representing complex situations, and to evaluate test traces and compute test coverage metrics.

Evaluating Symbolic Execution-Based Test Tools

In recent years several symbolic execution-based tools have been developed to automatically select relevant test inputs from the source code of the system under test. However, each of these tools has different advantages, and there is no detailed feedback available on the actual capabilities of the various tools. In order to evaluate test input generators we collected a representative set of programming language concepts that should be handled by the tools, mapped them to 300 code snippets that would serve as inputs for the tools, created an automated framework to execute and evaluate these snippets, and performed experiments on four Java and one .NET test generator tools. The results highlight the strengths and weaknesses of each tool, and identify hard code parts that are difficult to tackle for most of the tools. We hope that our research could serve as actionable feedback to tool developers and help practitioners assess the readiness of test input generation.

Mobile Systems from a Validation Perspective: a Case Study

Advances in wireless networking have yielded the development of mobile applications. However, sound technology to specify, design and validate such applications is still to be investigated. In order to exemplify some of the challenges that are raised, this paper reports on a case study: a group membership protocol for ad hoc networks. The protocol has been analyzed by reviewing the specification and the code, and then by testing the implementation. The outcomes provides us with hints for research direction.

Model-based Automatic Test Generation for Event-Driven Embedded Systems using Model Checkers

Testing is an essential, but time and resource consuming activity in the software development process. In the case of model-based development, among other subtasks test construction and test execution can be partially automated. Our paper describes the implementation of a test generator framework that uses an external model checker to construct test sequences. The possible configurations of the model checker are examined by measuring the efficiency of test construction in the case of different statechart models of event-driven embedded systems. The generated test cases are transformed and executed on common testing frameworks (JUnit, rational robot) and the effectiveness of tests are measured using code coverage metrics

Comparing Robustness of AIS-Based Middleware Implementations

To enable the interoperability of high availability (HA) middleware systems the Service Availability Forum has released a set of open specifications. The benefit of having open specifications is the choice of implementations available from different vendors. When one chooses a product, one of the selection criteria (besides performance) is the robustness of the implementation, as the crashing or hanging of such a HA middleware causes the failure of the whole system. The challenge is to develop the appropriate technology for measuring and comparing robustness of HA middleware implementations. Based on our earlier results, we present a set of automatic testing tools and a benchmark suite constructed using these tools. We demonstrate the robustness testing approach by comparing the results of benchmarking carried out on three HA middleware implementations.

Robustness Testing Techniques and Tools

Robustness is an attribute of resilience that measures the behaviour of the system under non-standard conditions. Robustness is defined as the degree to which a system operates correctly in the presence of exceptional inputs or stressful environmental conditions. As triggering robustness faults could in the worst case scenario even crash the system, detecting this type of faults is of utmost importance. This chapter presents the state of the art on robustness testing by summarizing the evolution of basic robustness testing techniques, giving an overview of the specific methods and tools developed for major application domains, and introducing penetration testing, a specialization of robustness testing, which searches for security vulnerabilities. Finally, the use of testing results in resilience modelling and analysis is discussed.

TERMOS: A Formal Language for Scenarios in Mobile Computing Systems

This paper presents TERMOS, a UML-based formal language for specifying scenarios in mobile computing systems. TERMOS scenarios are used for the verification of test traces. They capture key properties to be checked on the traces, considering both the spatial configuration of nodes and their communication. We give an overview of the TERMOS design and semantics. As part of the semantics, we present the principle of an algorithm that computes the orders of events from a scenario. Two proof-of-concept prototypes have been developed to study the realization of the algorithm.

Analytics of resource transients in cloud-based applications

Guaranteeing QoS of services deployed in clouds is a key issue in cloud environments. Cloud services rely heavily on sharing resources between tenants; users have only partial knowledge and control of them. Limited observability and controllability make guaranteeing QoS a challenging task. Many important classic approaches to QoS assurance cannot be adopted, as for a tenant resource arbitration is a black box. Unexpected changes in resource allowance and characteristics introduce novel risks for demanding applications, most importantly soft real-time ones. We introduce the concept of applicationintegrated early warning sensors – ‘mystery shoppers’ – to increase the observability of the platform performability state. Mystery shoppers are special, continuously running benchmarks that run as low footprint applications. They deliver fine-grained reports by simulating application resource usage and measuring platform characteristics. This enables inferring the hidden resource sharing characteristics of public clouds. The derived metrics can aid deployment planning and control application-level fault tolerance mechanisms.

Robustness Testing of Standard Specifications-Based HA Middleware

Using middleware implementations, instead of integrating the fault tolerance in the applications themselves, for providing stateful services highly availably has become the best practice in many industries including the telecommunication, computing and other areas. Robustness of these implementations toward user failures is essential for the overall availability of the systems. This paper summarizes the methodology for executing robustness tests on Service Availability Forum Application Interface Specification based middleware and describes the results of the conducted experiments with the Open SAF open source middleware implementation. Finally, the results of the measurements/experiments are analyzed using the AMBERRAW Data Repository.