The iterative and incremental nature of software development using models typically makes a model of a system incomplete (i.e., partial) until a more advanced and complete stage of development is reached. Existing model execution approaches (interpretation of models or code generation) do not support the execution of partial models. Supporting the execution of partial models at early stages of software development allows early detection of defects, which can be fixed more easily and at lower cost. This paper proposes a conceptual framework for the execution of partial models, which consists of three steps:static analysis,automatic refinement, andinput-driven execution. First, a static analysis that respects the execution semantics of models is applied to detect problematic elements of models that cause problems for the execution. Second, using model transformation techniques, the models are refined automatically, mainly by adding decision points where missing information can be supplied. Third, refined models are executed, and when the execution reaches the decision points, it uses inputs obtained either interactively or by a script that captures how to deal with partial elements. We created an execution engine calledPMExecfor the execution of partial models of UML-RT (i.e., a modeling language for the development of soft real-time systems) that embodies our proposed framework. We evaluatedPMExecbased on several use-cases that show that the static analysis, refinement, and application of user input can be carried out with reasonable performance, and that the overhead of approach, which is mostly due to the refinement and the increase in model complexity it causes, is manageable. We also discuss the properties of the refinement formally, and show how the refinement preserves the original behaviors of the model.

The heterogeneity and complexity of Internet of Things (IoT) applications present new challenges to the software development process. Model-Driven Software Development (MDSD) is increasingly being recognized as a key paradigm in tackling many of these challenges, as evident by the emergence of a significant number of MDSD frameworks targeting IoT in the past couple of years. At the heart of IoT applications are embedded and realtime systems, a domain where model-driven development is well-established and many existing tools have a proven track record. Unfortunately, only a handful of these tools support out-of-the-box integration with the IoT. In this work, we discuss the different design and implementation decisions for enabling existing actor-oriented MDSD tools for the IoT. Moreover, we propose an integration approach based on the use of proxy actors and system interfaces. The approach offers seamless and flexible integration of external IoT devices into the user's model. We implement and evaluate our approach using the MDSD tool Papyrus for Realtime as a testbed.

Model Driven Engineering (MDE) techniques raise the level of abstraction at which developers construct software. However, modern cyber-physical systems are becoming more prevalent and complex and hence software models that represent the structure and behavior of such systems still tend to be large and complex. These models may have numerous if not infinite possible behaviors, with complex communications between their components. Appropriate software testing techniques to generate test cases with high coverage rate to put these systems to test at the model-level (without the need to understand the underlying code generator or refer to the generated code) are therefore important. Concolic testing, a hybrid testing technique that benefits from both concrete and symbolic execution, gains a high execution coverage and is used extensively in the industry for program testing but not for software models. In this paper, we present a novel technique and its tool mCUTE1, an open source 2 model-level concolic testing engine. We describe the implementation of our tool in the context of Papyrus-RT, an open source Model Driven Engineering (MDE) tool based on UML-RT, and report the results of validating our tool using a set of benchmark models.

This paper presents PMExec, a tool that supports the execution of partial UML-RT models. To this end, the tool implements the following steps: static analysis, automatic refinement, and input-driven execution. The static analysis that respects the execution semantics of UML-RT models is used to detect problematic model elements, i.e., elements that cause problems during execution due to the partiality. Then, the models are refined automatically using model transformation techniques, which mostly add decision points where missing information can be supplied. Third, the refined models are executed, and when the execution reaches the decision points, input required to continue the execution is obtained either interactively or from a script that captures how to deal with partial elements. We have evaluated PMExec using several use-cases that show that the static analysis, refinement, and application of user input can be carried out with reasonable performance, and that the overhead of approach is manageable. https://youtu.be/BRKsselcMnc Note: Interested readers can refer to [1] for a thorough discussion and evaluation of this work.

Device‐to‐device (D2D) offloading has been shown to be a highly effective technique to enhance the performance of wireless networks. Yet, for any two mobile users to share data efficiently and reliably via D2D links, they should be in close proximity for long enough period of time, share similar content interests, and have some level of incentive and trust to cooperate. In this work, we focus on the practical implementation aspects of D2D data sharing taking into account realistic operational conditions. To this end, we design and conduct an experimental study to collect location and neighbor discovery data from 38 mobile users in a university campus over several weeks using our own customized crowdsourcing Android mobile application. The collected data is then processed and utilized to empirically model mobility‐related parameters that include contact frequency, contact duration, and inter‐contact duration. The participating users did also fill a user interest survey in order to correlate mobility and connectivity patterns with content interests and social network relations. The obtained insights are then used to develop a practical implementation framework for designing effective D2D data sharing strategies. To test the proposed ideas under realistic operational constraints, we design and implement a social‐aware D2D data sharing Android mobile application and demonstrate its functionality and effectiveness using an example case study scenario.

We present a scalable mobile multimedia streaming system with device-to-device cooperation that enables common content distribution in dense wireless networking environments. This is particularly applicable to use cases such as delivering real-time multimedia content to fans watching a soccer game in a stadium or to participants attending a major conference in a large auditorium. The key novel characteristics of our system include seamless neighbor discovery and link quality estimation, intelligent clustering and channel allocation algorithms based on constrained minimum spanning trees, robustness against device mobility, and device centric operation with no changes to existing wireless systems. We demonstrate the functionality of the proposed system on Android devices using heterogeneous networks (cellular/WiFi/WiFi-Direct) and show the formation of multiple clusters to allow for scalable operation. The gained insights will help bridge the gap between theoretical and simulation based research conducted in this area and practical operation taking into account the capabilities and limitations of existing wireless technologies and smartphones/tablets.

We introduce the notion of a virtual topology and explore the use of search-tree indexing to achieve highly scalable parallel search-tree algorithms for NP-hard problems. Vertex Cover and Cluster Editing are used as case studies.