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Mutation testing is a method used to assess and improve the fault detection capability of a test suite by creating faulty versions, called mutants, of the system under test. Evolutionary Mutation Testing (EMT), like selective mutation or mutant sampling, was proposed to reduce the computational cost, which is a major concern when applying mutation testing. This technique implements an evolutionary...
In this paper, we present a new, computationally inexpensive method for preventing premature convergence in multimodal evolutionary algorithms by population injection. Our method avoids the premature convergence of the population around one or multiple local optima by maintaining an adequate amount of genetic diversity. The technique does not require any setup or maintenance effort during runtime...
Data stream processing addresses the need for high-throughput near real-time data processing, which can be considered as one part of Big Data or Fast Data. In this paper, we study the local parallelization of stream processing on a single multi-core Central Processing Unit (CPU) computer system, which, in our opinion, was not sufficiently addressed yet. In distributed systems, optimizing the local...
Stream-based data processing systems, such as Complex Event Processing or data stream mining systems, may be composed of several components which may be implemented in various programming languages. In distributed scenarios, computer networks typically represent important bottlenecks. However, the performance of data exchange in local contexts may be as important as the performance of data exchange...
While network traffic acquisition and processing is typically done with languages like C that allow low-level hardware access and optimizations, languages like Java and their ecosystems aim at easing complex tasks. With a combination of both, strengths can be combined such that more powerful and versatile network traffic processing systems can be engineered. However, while approaches using languages...
We present an approach for flexible distributed remote packet capturing with additional self-adaptivity and cooperation capabilities. Such techniques are needed for gaining comprehensive insight into large computer networks. With our system it is possible to operate multiple distributed remote packet capturing sensors from arbitrary locations. Advanced features like self-adaptivity or the cooperative...
This paper presents a tool, called PTTAC, that automatizes a formal framework to perform passive testing for systems where there is an asynchronous communications channel between the tester and the system. Given a property, the methodology allows us to check that a trace being observed satisfies that property. The proposed solution checks properties against traces in polynomial time, with a low need...
The combination of low-level network data acquisition and higher-level frameworks results in more powerful and efficient network analysis and surveillance systems and opens up new possibilities for leveraging low-level network traffic data. There is, however, a gap between low-level network traffic data acquisition techniques and higher-level frameworks. This gap complicates the integration of low-level...
Maintaining correctly operating computer networks is paramount for assuring properly operating information technology infrastructures. Thereby, the acquisition of network traffic data is one of the first steps. The acquisition of network traffic, however, can be very challenging, e.g., with respect to performance and resource requirements. In this paper, we analyze the possibility of using packet...
Event processing queries are intended to process continuous event streams. These queries are partially similar to traditional SQL queries, but provide the facilities to express rich features (e.g., pattern expression, sliding window of length and time). An error while implementing a query may result in abnormal program behaviors and lost business opportunities. Moreover, queries can be generated with...
In recent years, the focus on higher education learning has shifted from knowledge to skills, with the interpersonal skills likely being the most difficult to assess and work with. Wikis ease open collaboration among peers. The massive adoption of computers and the Internet both in the classroom and by students makes it possible to use them for grading. A number of these skills can be assessed by...
Obtaining the expected performance of a workflow is much simpler if the requirements for each of its tasks are well defined. However, most of the time, not all tasks have well-defined requirements, and these must be derived by hand. This can be an error-prone and time consuming process for complex workflows. In this work, we present an algorithm which can derive a time limit for each task in a workflow,...
Applying mutation testing to a program written in a certain language requires that a set of mutation operators is defined for that language. The mutation operators need to adequately cover the features of that language in order to be effective. In this work, we evaluate qualitatively the operators defined for the Web Services Business Process Execution Language 2.0 (WS-BPEL) and study the differences...
Nowadays, Web Service (WS) compositions play an important role in business processes. Languages for composing web services, such as the OASIS WS-BPEL 2.0 standard, open a new field for large-scale programming. However, they also present a challenge for traditional quality assurance because of the inclusion of specific instructions for concurrency, fault compensation, and dynamic service discovery...
This work presents a quantitative evaluation of the quality of a set of mutation operators for WS-BPEL 2.0 (Web Services Business Process Execution Language), an OASIS standardized language for the composition of Web Services. A series of experiments is conducted, aiming to determine how selective operators are for the qualification of test cases and, more generally, the quality of the operators themselves...
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