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Dealing with highly configurable systems is generally very complex. Researchers and practitioners have conceived hundreds of different analysis techniques to deal with different aspects of configurable systems. One large focal point is the testing of configurable software. This is challenging due to the large number of possible configurations. Moreover, tests themselves are rarely configurable and instead built for specific configurations. However, existing tests need to be adapted to run on a different configuration. In this paper, we report on an experiment about automatically reusing existing tests in configurable systems. We used manually developed tests for specific configurations of three configurable systems and investigated how changing the configuration affects the tests. Subsequently, we employed an approach for automated reuse to generate new test variants (by reusing from existing ones) for combinations of previous configurations and compared their results to the ones from existing tests. Our results showed that we could directly reuse some tests for different configurations. Nonetheless, our automatically generated test variants generally yielded better results. Our generated tests had a higher or equal success rate to the existing tests in most cases. Even in the cases the success rate was equal, our generated tests generally had higher code coverage.

The use of nanobots and in-body nano communication techniques offer manifold options for next generation health care and precision medicine. Scientific progress allows to place nanobots in the human circulatory system and enabled them to exchange data and information among each other as well as to external gateway systems. One of the frequently asked questions is how to identify the optimal number of bots for a task, monitoring frequencies, and communication technologies. In this paper, we introduce and study the age of information (AoI) as a comprehensive metric for describing the performance of in-body nano communication networks. We use the AoI concept in an in-body measurement scenario. Our results clearly demonstrate that AoI is a very helpful tool to study the performance of in-body nano communication networks.

DNA-based molecular communication is a novel paradigm for nanoscale computation and communication that uses self-assembling DNA message molecules. Due to their design, these message molecules can compute mathematical operations while self-assembling. They can be used in DNA-based nanonetworks to detect DNA sequences and compute information for releasing either medication or other molecules. This paradigm avoids many limitations that electromagnetic nanonetworks currently face. This paper presents a variety of novel advantages and use cases for DNA-based molecular communication. For many of those, no feasible solution exists today. DNA-based molecular communication can even detect and consider multiple different DNA sequences for decision-making. Furthermore, it allows for adjustable error correction, immediate treatments, bio-compatibility, and the use of already available materials.

Developing interactive systems and testing with realistic scenarios requires a detailed understanding of how these systems are used in their real environment. In this paper, we report on our experience from implementing a usage monitoring approach for the touch-enabled human machine interface of an industrial machine. The approach supports automated recording of user interface events as basis for analyzing interactions of users with the system. It collects information about navigation paths to different screens, activities on these screens, and the usage of functionality provided by the application. We evaluated three different approaches to integrate the required usage monitoring into the UI, considering aspects such as necessary changes to the existing code base, dependencies to third-party libraries, and the entailed performance overhead. The paper provides a detailed description of the implementation of the selected approach and a discussion of the lessons we learned from integrating the monitoring in an existing application.

Evolving configurable software poses unique challenges, due to dependencies between the configuration knowledge and the assets that implement the system. Despite a lot of research in the area of configurable software evolution many open challenges subsist, which hamper industrial adoption of different techniques. For instance, there is not much research on the co-evolution of tests and the configuration space. A challenge for this is that the configuration space is often not clearly defined and reasoning over its evolutions and the implication from it is difficult. In this paper, we study the configuration space of the web-based bug tracker Bugzilla, a highly configurable system, replicating the analysis of previous research. In addition, we analyze the evolution of the configuration space over several versions of the system to investigate the changes that were made over the revisions spanning the development of several years and their implications and open challenges.

Cyber-physical systems, i.e., systems that seamlessly integrate computation and physical components, are typically highly-configurable systems. Testing such systems is particularly challenging because they comprise a large number of heterogeneous components that can be configured and combined in different ways. Despite a plethora of work investigating software testing in general and software product line testing in particular, variability in tests and how industry does actually manage testing highly configurable cyber-physical systems is not well understood. In this paper, we report the results of a multiple case study we conducted with three companies developing and maintaining highly-configurable cyber-physical systems focusing on their testing practices, with a particular focus on how they manage variability in tests. We conclude that experienced-based selection of configurations for testing is currently predominant. Variability modeling techniques are not utilized and the dependencies between configuration options are only partially modeled at best. However, the companies are aware of the situation and have the need and desire to cover more configuration combinations by automated tests. This in turn raises many questions, which might also be of interest to the scientific community and motivate future research.

Software product lines (SPLs) are known for improving productivity and reducing time-to-market through the systematic reuse of assets. SPLs are adopted mainly by re-engineering existing system variants. Feature location techniques (FLTs) support the re-engineering process by mapping the variants’ features to their implementation. However, such FLTs do not perform well when applied to single systems. In this way, there is a lack of FLTs to aid the re-engineering process of a single system into an SPL. In this work, we present a hybrid technique that consists of two complementary types of analysis: i) a dynamic analysis by runtime monitoring traces of scenarios in which features of the system are exercised individually, and ii) a static analysis for refining overlapping traces. We evaluate our technique on three subject systems by computing the common metrics used in FL research. We thus computed Precision, Recall, and F-Score at the line- and method-level of source code. In addition to that, one of the systems has a ground truth available, which we also used for comparing results. Results show that our FLT reached an average of 68-78% precision and 72-81% recall on two systems at the line-level, and 67-65% precision and 68-48% recall at the method-level. In these systems, most of the implementation can be covered by the exercise of the features. For the largest system, our technique reached a precision of up to 99% at the line-level, 94% at the method-level, and 44% when comparing to traces. However, due to its size, it was difficult to reach high code coverage during execution, and thus the recall obtained was on average of 28% at the line-level, 25% at the method-level, and 30% when comparing to traces. The main contribution of this work is a hybrid FLT, its publicly available implementation, and a replication package for comparisons and future studies.

Traditional routing approaches in VANETs use vehicular to vehicular (V2V) communication. Currently the state of the art shows that using only V2V communication has limitations to face the high mobility and intermittent connections in VANETs. Furthermore, those approaches can be used only in relatively small areas. In this sense, using mobile or fixed nodes to assist the routing process has the potential not only to improve the routing performance, instead to increase the network scalability and access to the cloud and internet. On the other hand, position-based routing has shown to be the most suitable strategy to face the high mobility. This paper, presents a new research direction on 3D-routing for VANETs, in particular, it is focused on position-based routing assisted by mobile or fixed nodes such as Unmanned Aerial Vehicles (UAVs), Road Side Units (RSUs), Mobile Gateways (MGs) or Base Stations (BSs), which perform specific functions to improve the routing performance.

BloodVoyagerS (BVS) is an ns-3 module that simulates the global movement of nanobots in the human body. The Blood-VoyagerS Visualizer (BVS-Vis) is a multi-platform visualization tool for result files of BVS. BVS-Vis shows the distribution of the simulated nanobots over time in a three-dimensional cardiovascular model. The animation can be rotated, moved, zoomed in and it is possible to navigate through different time steps. For a quick interpretation of simulation results, a heat map of the nanobots concentration can be generated via post-processing. BVS-Vis is available as a website and as a complete docker-compose setup. It increases the workflow with BVS significantly and enables prompt analysis of simulation results.

We present a novel simulation framework bridging the gap between in-body nano communication and out-of-body body area network (BAN). We assume nanobots freely flowing within the blood system. Their mobility can be modeled using the BloodVoyagerS module. The communication channels are modeled using proximity (nanobot to nanobot), proximity and ultrasonic communication (nanobot to a gateway), and standard IEEE 802.15.4 for BAN communication. In our simulation framework, we rely on ns-3 to model all the three independent communication channels to, for the first time, study the end-to-end communication performance from nanobots to a connected host system. We consider the system a fundamental basis for more advanced studies of such integrated and very heterogeneous communication systems.

In this paper, we present the concept of a complex framework, which is primarily designed to model and simulate the structures of and the processes in the human body and the interaction of nanobots with it. Medical nanobots are envisioned to perform their work in the body, for example by recognizing and destroying cancer cells. They are generally attributed an important role in a future precision medicine-based health system. It is crucial to simulate the use of nanobots in a human body before they are actually used. However, only with a comprehensive body simulation framework, like the presented medical holistic simulation architecture (MEHLISSA), it is possible to achieve meaningful results. As we model the human body as close to reality as feasible, this allows for reliable statements about the effectiveness and efficiency of the use of nanobots in vivo. To illustrate the advantages of an holistic simulation, we discuss the use case of metastasis prevention modelled in MEHLISSA.

Component-based software development (CBSD) is one of the main programming paradigms of the last decades. The main idea of CBSD is to modularize a system as a configuration of multiple interacting components. Components interact with each other via dedicated component interfaces hiding a component's implementation and making components interchangeable. In this paper, we present an early investigation of unit testing practices of open source component-based software systems with the goal to find out how component-based software systems are actually tested and how to improve unit testing practices as part of future research. Our preliminary results show that unit tests typically directly test the component implementation and not dedicated component APIs. The method coverage of component APIs varied between 17% and 34% in the analyzed projects.

Automated test case generation techniques usually aim to maximize some coverage criteria. For object oriented languages, like Java, the branches that can be reached in source code, frequently depend on the internal object state. Meaning certain branches will only be taken, if fields inside the tested class are set to specific values. It is however not obvious how much of the internal object state can be controlled. In this paper, we analyzed a corpus of 110 open source systems to evaluate how settable their classes are. Meaning we looked for ways that fields inside classes can be written. For instance, we analyzed the source code to identify setter methods that can be used to set the values of a field. Our results show that 66.5% of fields can be set to a desired value, while 31.5% of fields may be only settable to particular values or require a more in depth analysis. Only for 2% of fields, we did not find any way to set their values.

Traditional Wireless Sensor Networks (WSNs) are single-channel based and mainly focus on energy-efficiency and scalability. Therefore, they may readily suffer from issues such as bandwidth insufficiency, interference, jamming and so on. With the deployment of dense sensor networks and the outset of multimedia technology, the intensity of the above-mentioned issues is further aggravated. To address those challenges, the researchers have employed multichannel technology in WSNs that focuses on increasing bandwidth/throughput while decreasing collision/congestion, delay, and energy consumption. For ascertaining a comprehensive exploration of multichannel technology in WSNs, this paper discusses in detail the important issues that are indispensable for providing high-performance and achieving Quality of Service (QoS) in multichannel WSNs. Further on, it evaluates a variety of multichannel MAC protocols under the stated design issues and classifies them into the categories Highly, Medium and Least-Robust, based upon aggregate-of-the-design-issues addressed by the corresponding multichannel MAC protocols for WSNs. Besides on the basis of channel access mechanism, each main category is sub-categorized into Time Division Multiple Access (TDMA), Carrier Sense Multiple Access (CSMA), Composite and Other-Novel classes whereby the functionality of the MAC protocols belonging to each class is briefly discussed along with relevant pros & cons. In addition to that, the survey delineates the implementation of the multichannel methodology in the emerging smart technologies of WSNs. In the end, future research directions are anticipated and a reasonable conclusion is put forth.

Multi-channel based routing approach may utilize more than one channel for communication and has the ability to provide high performance by more rigorously countering interference, collisions and re-transmissions than the single-channel routing methodology. This research work aims to establish guidelines for future research and development in the area of Wireless Sensor Networks (WSNs) based on the critical analysis of the prevalent multi-channel based routing protocols for WSNs. Due to extensive ongoing research in this domain, a significant number of multi-channel routing strategies have been presented which need to be discussed. To explore, this work not only reviews a variety of single/multi-path and single/multi-radio multichannel routing protocols for WSNs under a novel taxonomy, but also outlines their relevant pros and cons. In order to help design new multi-channel routing strategies for WSNs, an insightful review on the applications, current design issues and associated challenges of multichannel routing in WSNs are in-depth scrutinized. Towards the end, some prospect trends are put forth regarding multi-channel routing for WSNs which may provide a road map for future investigation.

Software testing helps developers to identify bugs. However, awareness of bugs is only the first step. Finding and correcting the faulty program components is equally hard and essential for high-quality software. Fault localization automatically pinpoints the location of an existing bug in a program. It is a hard problem, and existing methods are not yet precise enough for widespread industrial adoption. We propose fault localization via Probabilistic Software Modeling (PSM). PSM analyzes the structure and behavior of a program and synthesizes a network of Probabilistic Models (PMs). Each PM models a method with its inputs and outputs and is capable of evaluating the likelihood of runtime data. We use this likelihood evaluation to find fault locations and their impact on dependent code elements. Results indicate that PSM is a robust framework for accurate fault localization., 4 pages, 3 figures, 2 tables, 3rd Workshop on Validation, Analysis and Evolution of Software Tests

One of the biggest unsolved problems in nanonetwork research is the actual construction of the components required for building such networks. Most existing ideas are limited to partial solutions of construction of nanodevices, computation within them, and communication between them. While many ideas are promising, the problem remains how to combine those various building blocks into operational and efficient nanonetworks.

One of the main problems in nano computing and nano networking is the physical construction of nano machines. DNA is a prime candidate for nanoscale constructions because it is a chemically and structurally stable molecule. Short DNA strands can be combined to form so called DNA tiles. These tiles form the basic building blocks for bigger structures which come into existence through self-assembly - given a sufficient supply of different tiletypes, the tiles automatically bind together. Self-assembly is a functional tool at the nanoscale, where top-down interaction tends to be difficult.However, DNA-based construction is prone to errors. Therefore, algorithmic strategies mitigating these errors, by a system called proofreading, have been developed. In this paper, we adapt a two-dimensional proofreading strategy for three dimensions in order to create functional 3D structures at the nanoscale. An algorithm is presented which creates a scaled 3D proofreading tileset, given any 3D tileset. The algorithm creates a k x k x k block of Snaked Proofreading tiletypes for each tile t in the original tileset using O(|t|k3) tiletypes. These proofreading tilesets can be used to reliably assemble nanoscale devices or to scale up shapes while simultaneously reducing errors.

The evolution of variant-rich systems is a challenging task. To support developers, the research community has proposed a range of different techniques over the last decades. However, many techniques have not been adopted in practice so far. To advance such techniques and to support their adoption, it is crucial to evaluate them against realistic baselines, ideally in the form of generally accessible benchmarks. To this end, we need to improve our empirical understanding of typical evolution scenarios for variant-rich systems and their relevance for benchmarking. In this paper, we establish eleven evolution scenarios in which benchmarks would be beneficial. Our scenarios cover typical lifecycles of variant-rich system, ranging from clone & own to adopting and evolving a configurable product-line platform. For each scenario, we formulate benchmarking requirements and assess its clarity and relevance via a survey with experts in variant-rich systems and software evolution. We also surveyed the existing benchmarking landscape, identifying synergies and gaps. We observed that most scenarios, despite being perceived as important by experts, are only partially or not at all supported by existing benchmarks-a call to arms for building community benchmarks upon our requirements. We hope that our work raises awareness for benchmarking as a means to advance techniques for evolving variant-rich systems, and that it will lead to a benchmarking initiative in our community.

Dealing with highly configurable systems is generally very complex. Hundreds of different analysis techniques have been conceived to deal with different aspects of configurable systems. One large focal point is the testing of configurable software. This is challenging due to the large number of possible configurations and because tests themselves are rarely configurable and instead built for specific configurations. Existing tests can usually not be reused on other configurations. Therefore, tests need to be adapted for the specific configuration they are supposed to test. In this paper we report on an experiment about reusing tests in a configurable system. We used manually developed tests for specific configurations of Bugzilla and investigated which of them could be reused for other configurations. Moreover, we automatically generated new test variants (by automatically reusing from existing ones) for combinations of previous configurations. Our results showed that we can directly reuse some tests for configurations which they were not intended for. Nonetheless, our automatically generated test variants generally yielded better results. When applying original tests to new configurations we found an average success rate for the tests of 81,84%. In contrast, our generated test variants achieved an average success rate of 98,72%. This is an increase of 16,88%.

International audience; Most engineering tools do not provide much support for collaborating teams and today's engineering knowledge repositories lack flexibility and are limited. Engineering teams have different needs and their team members have different preferences on how and when to collaborate. These needs may depend on the individual work style, the role an engineer has, and the tasks they have to perform within the collaborating group. However, individual collaboration is insufficient and engineers need to collaborate in groups. This work presents a collaboration framework for collaborating groups capable of providing synchronous and asynchronous mode of collaboration. Additionally, our approach enables engineers to mix these collaboration modes to meet the preferences of individual group members. We evaluate the scalability of this framework using four real life large collaboration projects. These projects were found from GitHub and they were under active development by the time of evaluation. We have tested our approach creating groups of different sizes for each project. The results showed that our approach scales to support every case for the groups created. Additionally, we scouted the literature and discovered studies that support the usefulness of different groups with collaboration styles.

One of the most important research issues in the field of nanonetworks is the problem of constructing real networks in practice. To build such networks, one needs to create the nano-devices themselves as well as a computing and a communication mechanism. We already have developed such a concept based on DNA building blocks (so called DNA tiles), which is able to generate all three mechanisms by self-construction, basically by providing a sufficiently large number of specific DNA building blocks. Such networks are Turing complete; however, as we demonstrate in this paper, the number of required building blocks to execute computations by simulating Turing machines is large. We will show in this paper that the number can be reduced by using specific, more efficient sets of building blocks for problems that can be modeled as boolean formulas. For specific mathematical operations like And or Add , even smaller solutions/message molecules can be created. This paper presents small message molecules for frequently requested mathematical problems. We present nanonetworks for the Thres and Add operations. Thres operations can be used to register if critical concentrations of disease markers have been reached. Add forms the basis for many advanced communication protocols. Furthermore, message molecules for Mult , Xor and Inc are conceptualized. The presented message molecules are smaller and less error prone compared to the tilesets that result from more generic approaches. It is therefore more likely that they can be employed in groundbreaking wet-lab experiments in the near future.

Considering both channel quality and stability may enhance the likelihood of optimum channel decision for stream-based communication. Good quality stable channels may maintain a particular quality level during data stream transmission and thereby minimize channel switching overheads such as switching delay, energy consumption, and the associated data loss. Among the published multichannel MAC protocols for WSNs, only a few consider channel quality before assigning wireless channels. Whereas to the best of our knowledge, only few contemplates both channel quality and stability during stream-based communication, however, not very suitable for varying (noisy) environment. To bridge this gap, this work proposes a novel dynamic Multichannel Adaptive approach for Grading Immediate Channels (MAGIC). The MAGIC protocol may predict and classify the available channels under channel quality and stability assessment methodology and determines Local Preferred Channels (LPCs) in a noisy environment. Afterwards, the best among those channels may be selected (under some QoS criteria) for stream-based communication in WSNs. The proposed MAGIC algorithm minimizes channel processing overheads by considering only non-blacklisted channels during a communication session. Simulation results show that the MAGIC algorithm achieves better performance than the counterparts in terms of channel switching delay, energy consumption, and the associated throughput loss.

International audience; Model and code co-changing is about the coordinated modification of models and code during evolution. Intermittent inconsistencies are a common occurrence during co-changing. A partial co-change is the period in which the developer changed, say, the model but has not yet propagated the change to the code. Inconsistency feedback can be provided to developers for helping them to complete partial co-changes. However, there is no evidence whether such inconsistency feedback is useful to developers. To investigate this problem, we conducted a controlled experiment with 36 subjects who were required to complete ten partially completed change tasks between models and code of two non-trivial systems. The tasks were of different levels of complexity depending on how many model diagrams they affected. All subjects had to work on all change tasks but sometimes with and sometimes without inconsistency feedback. We then measured differences between task effort and correctness. We found that when subjects were given inconsistency feedback during tasks, they were 268% more likely to complete the co-change correctly compared to when they were not given inconsistency feedback. We also found that when subjects were not given inconsistency feedback, they nearly always failed in completing co-change tasks with high complexity where the partially completed changes were spread across different diagrams in the model. These findings suggest that inconsistency feedback (i.e. detection and repair) should form an integral part of co-changing, regardless of whether the code or the model changes first. Furthermore, these findings suggest that merely having access to changes (as with the given partially completed changes) is insufficient for effective co-changing.

Unlike the scalar data (such as temperature, pressure and humidity), the vector data (such as image, audio and video) necessitates more stringent Quality of Service (QoS) requirements in terms of bandwidth, delay, reliability and information security. These QoS requirements can be hardly achieved in a proper fashion by using a single channel for wireless communication. However, multichannel methodology may assist in accomplishing these QoS requirements by making possible parallel communication, enhancing throughput/delivery ratio, reducing transmission delay and countering jamming attacks. Furthermore, enabling data gathering at multiple points (i.e. multisink approach) may improve QoS by handling congestion, avoiding single point of failure issue and making possible load balancing between the available routes towards the corresponding destinations. To achieve reliable communication in stream based multichannel Wireless Sensor Networks (WSNs), this work proposes a novel QoS-aware Cross-layered Multichannel Multisink Routing protocol (QCM2R) for WSNs. For substantiating the performance of QCM2R protocol, the simulations are performed in NS-2 demonstrating the performance superiority of the proposed QCM2R protocol against the counterpart in terms of network lifetime, reliability, delay and throughput.

The development of future network architectures and of wireless devices needs to take the challenges in developing region into account. The unexpectedly intermittent connections due to sparse deployment, dynamic topology, or node mobility create a new challenge environment that has not been tackled before in both wired and wireless networks. Many developing regions’ network infrastructures have a lack of a reliable connectivity, such as frequent packet losses and bit errors due to low-quality hardware, and frequent network disconnections. Delay Tolerant Networks were developed to be used as an advanced step towards building a future reliable interplanetary Internet. It has shown significant potential for building systems to deliver public services to remote parts of developing countries. Most of the current work has focused on the problem of message delivery within a single region with the same network infrastructure and namespace. However, many deployments in developing countries will probably involve routing between multiple regions, based on technologies such as WiMAX, Satellites or Ad-hoc networks with short-range radio devices, as in the case of mobile phones with Bluetooth interface. In this paper, we consider the design and implementation of an infrastructure based solutions that effectively handle the intermittent connection in DTNs, for a scenario with hybrid DTN and infrastructure networks (HIDTN) which employs the global handover technologies to manage the performance of developing regions’ network infrastructures.

Robust and effective support for the detection and management of software features and their interactions is crucial for many development tasks but has proven to be an elusive goal despite extensive research on the subject. This is especially challenging for variable systems where multiple variants of a system and their features must be collectively considered. Here an important issue is the typically large number of feature interactions that can occur in variable systems. We propose a method that computes, from a set of known source code level interactions of n features, the relevant interactions involving n+1 features. Our method is based on the insight that, if a set of features interact, it is much more likely that these features also interact with additional features, as opposed to completely different features interacting. This key insight enables us to drastically prune the space of potential feature interactions to those that will have a true impact at source code level. This substantial space reduction can be leveraged by analysis techniques that are based on feature interactions (e.g Combinatorial Interaction Testing). Our observation is based on eight variable systems, implemented in Java and C, totaling over nine million LoC, with over seven thousand feature interactions.

Software Product Lines (SPLs) are families of related software systems distinguished by the set of features each one provides. The commonly large number of variants that can be derived from an SPL poses a unique set of challenges, because it is not feasible to test all the individual variants. Over the last few years many approaches for SPL testing have been devised. They usually select a set of variants to test based on some covering criterion. A problem when evaluating these testing approaches is properly comparing them to one another. Even though some benchmarks have been proposed, they focus on covering criteria and do not consider fault data in their analysis. Considering the dire lack of publicly available fault data, in this paper we present the first results of our ongoing project to introduce simulated faults into SPLs along with using evolutionary techniques for synthesizing unit test cases for SPL examples.

This chapter focuses on different aspects of development and characterization of highly concentrated protein formulations. This includes the introduction of predictive tools used during early development, specific challenges for analytical methods, and extended characterization of rheological and structural properties. The application of predictive tools during clinical lead selection and early-stage development helps to assess whether a selected clinical candidate may successfully pass the challenges of a high-concentration product in later development. In particular, parameters like B22 (second virial coefficient) and kD (diffusional interaction parameter) are described and underlying principles, technologies, limitations, and applicability to highly concentrated formulations are elaborated. The specific challenges of high-concentration protein formulations with respect to analytical characterization are discussed in detail and practical recommendation is given. Different common techniques to measure viscosity are described including dependencies on protein concentration, temperature, and shear stress. Structural characterization of highly concentrated protein formulations requires analytical tools capable to measure in the non-diluted regime. Only a limited number of analytical techniques are available for this challenging task like small-angle scattering techniques (SAS) and quartz crystal impedance analysis (QCIA)/microbalance with dissipation monitoring (QCM-D). These techniques are described, and measuring principle, applications in literature as well as limitations are outlined.

This paper presents monitoring as a service for networked medical cyber-physical systems in the operating room based on the recent IEEE 11073 standards for interoperable medical device communication. Runtime Verification techniques are used to allow for a formal specification and verification. Based on the specification so called monitors are automatically synthesized. At runtime, the monitors observe the communication of the interconnected systems and examine whether they adhere to the specification. This facilitates the handling of the high safety requirements of medical cyber-physical systems and to increase their reliability. In addition, we outline the development and deployment process of the monitors and depict how the framework can be extended to react when misbehavior is detected. As a case study the interconnection of an ultrasound dissector and a microscope is used. Our benchmarks show that the monitoring overhead is substantially lower than what is required for our practical application.

This paper proposes and motivates a combination of different technologies to enable the construction of arbitrary three-dimensional shapes at the nanoscale with certain a"-mounts of computational power. The aforementioned technologies are tile-based self-assembly systems and quan"-tum-dot cellular automata. Both technologies are in theory capable of universal computation, while self-assembly systems may better be utilized for construction-purposes. Since the decrease in size of CMOS technology explained by Moores law approaches its lower bound due to quantum effects at the nanoscale, we find it necessary to analyze computational models like QCA to better incorporate future requirements. This paper explains the aforementioned mathematical models and defines a possible combination of both.

Akyildiz et al. envisioned the use of nanonetworks as a new paradigm for computation and communication on a very small scale. We present a new approach to implement nanonetworks with molecular communication using tile-based self-assembly systems on the basis of DNA. In this model, the medium of communication is filled with DNA-based molecules. Furthermore, some nanobots are capable of creating or releasing said molecules. Once present, they can be detected by other nanobots and interpreted as messages. Some DNA-based molecule systems are capable of universal computation. We show that it is possible to construct systems, in which the evaluation to true of an arbitrary decision problem is a precondition for the assembly of a message molecule. We relocate computations from nanobots into message molecules, thereby revolutionizing the paradigm for computation in nanonetworks. This approach can be interpreted as computation inside the communication channel. We further present message molecules that only assemble if a marker has been detected at least k times, as a proof of concept.

Robust and effective support for the detection and management of features and their interactions is crucial for many software development tasks but has proven to be an elusive goal despite the extensive research and practice on the subject. Providing the required support becomes even more challenging with variable software whereby multiple variants of a system and their features must be collectively considered. An important premise to provide better support for feature interactions in variable systems is the need of a deeper understanding on how features interact at different levels starting from the source level. In this context, recent work has looked at feature interactions from different angles and for different purposes, for instance for developing performance models, extracting interfaces for maintenance or describing feature evolution patterns. However, there is a gap in understanding how features interact in fact at the source level in contrast with how features ought to interact according to variability models that describe the valid combinations of features in variable software systems. In this paper we perform an empirical study to explore this gap. We use seven case studies, implemented in Java and C, totalling over nine million LoC, and analysed over seven thousand feature interactions. Our study revealed important inconsistencies between how feature interactions occur at source level and how they are modeled, and corroborated that the majority of source level interactions involve less than three features. We discuss the implications of our findings and avenues for further research.

Internet of Things (IoT) is changing our life for the better. IoT covers various heterogeneous devices which are sensing the environment and/or monitoring a special event in the network. These devices are mostly mobile and are wirelessly connected either to each other or to the Internet. Additionally, IoT devices run many different applications and services which provide the consumers with data and information. This paper focuses on the design and implementation of an Application Programming Interface (API) for IoT services using the Named Data Networking (NDN). NDN provides an efficient and intelligent communication paradigm for constrained devices like in IoT and uses named content to transmit data in the network. We extend the IoT-NDN architecture and add a new layer for IoT services which will effectively improve the performance of communication between the heterogeneous devices and the services integrated in IoT-NDN. Furthermore, we show the usage of our API and give a small example of network time synchronisation on IoT devices. This illustrates how flexible and lightweight is our approach for several services implemented on heterogeneous devices in IoT.

Extensive work on Search-Based Software Testing for Software Product Lines has been published in the last few years. Salient among them is the use of similarity as a surrogate metric for t-wise coverage whenever higher strengths are needed or whenever the size of the test suites is infeasible because of technological or budget limitations. Though promising, this metric has not been assessed with real fault data. In this paper, we address this limitation by using Drupal, a widely used open source web content management system, as an industry-strength case study for which both variability information and fault data have been recently made available. Our preliminary assessment corroborates some of the previous findings but also raises issues on some assumptions and claims made. We hope our work encourages further empirical evaluations of Combinatorial Interaction Testing approaches for Software Product Lines.

Virtual testbeds model them by seamlessly integrating physical, simulated, and emulated sensor nodes and radios in real time.

In this survey, we describe the state of the art for research on experimentally-driven research on networks of tiny artifacts. The main topics are existing and planned practical testbeds, software simulations, and hybrid approaches; in addition, we describe a number of current studies undertaken by the authors.

In recent years, tremendous progress has been made in understanding the dynamics of vehicle traffic flow and traffic congestion by interpreting traffic as a multiparticle system. This helps to explain the onset and persistence of many undesired phenomena, for example, traffic jams. It also reflects the apparent helplessness of drivers in traffic, who feel like passive particles that are pushed around by exterior forces; one of the crucial aspects is the inability to communicate and coordinate with other traffic participants. We present distributed methods for solving these fundamental problems, employing modern wireless, ad-hoc, multi-hop networks. The underlying idea is to use these capabilities as the basis for self-organizing methods for coordinating data collection and processing, recognizing traffic phenomena, and changing their structure by coordinated behavior. The overall objective is a multi-level approach that reaches from protocols for local wireless communication, data dissemination, pattern recognition, over hierarchical structuring and coordinated behavior, all the way to large-scale traffic regulation. In this article, we describe three types of results: (i) self-organizing and distributed methods for maintaining and collecting data (using our concept of Hovering Data Clouds ); (ii) adaptive data dissemination for traffic information systems; (iii) methods for self-recognition of traffic jams. We conclude by describing higher-level aspects of our work.

Ignoring the generality in the design of Wireless Sensor Networks (WSNs) applications limits their benefits. Furthermore, the possibilities of future extension and adaptation are also restricted. In this paper, several methods to enhance the generality in WSNs are explained. We have further evaluated the suitability of these methods in centralized and de-centralized management scenarios.

Compared to other middleware approaches like CORBA or Java RMI the protocol overhead of SOAP is very high. This fact is not only disadvantageous for several performance-critical applications, but especially in environments with limited network bandwidth or resource-constrained computing devices. Although recent research work concentrated on more compact, binary representations of XML data only very few approaches account for the special characteristics of SOAP communication. In this article we will discuss the most relevant state-of-the-art technologies for compressing XML data. Furthermore, we will present a novel solution for compacting SOAP messages. In order to achieve significantly better compression rates than current approaches, our compressor utilizes structure information from an XML Schema or WSDL document. With this additional knowledge on the “grammar” of the exchanged messages, our compressor generates a single custom pushdown automaton, which can be used as a highly efficient validating parser as well as a highly efficient compressor. The main idea is to tag the transitions of the automaton with short binary identifiers that are then used to encode the path trough the automaton during parsing. Our approach leads to extremely compact data representations and is also usable in environments with very limited CPU and memory resources.

The applicability of Delay Tolerant Network (DTN) routing protocols is generally quite restricted to extremely mobile environments. All nodes including terminal hosts and routers are mobile, and there is no infrastructure available. This paper presents the utilization of a scheme that combines multiple DTN regions for infrastructure-based DTN communication. This is achieved through stationary devices with store-and-forward capabilities located at the border between various areas which cover both infrastructure-less and infrastructure-based environments. In this scenario, the nodes' movements are restricted to their region; sources and destinations might be located in different regions. The fixed nodes collect all the messages created by sources and transfer it to the destination nodes in other regions, if within communication range. Therefore, the existence of fixed nodes shall resolve the problem of mapping routes for different regions. In addition, we analyze the influence of diverse network conditions when the mobile nodes move around the network area.

Internet of Things (IoT) systems have become a main part in future internet research. In IoT, heterogeneous devices are connected to sense the environment or to observe special tasks. Many research fields use the seamless IoT infrastructure to interact between the integrated devices and diverse services. Considering the healthcare research, the number of elderly people is rapidly growing and they need more support in their life. Therefore, a new technology called Ambient Assisted Living (AAL) has been proposed to better increase the life quality of elderly people. In AAL, the devices are mostly connected wirelessly to each other and/or to a healthcare service centre. It is challenging to build such a system and its deployment should be seamless and flexible. Therefore, IoT provides all main characteristics necessary for AAL environment and applications, including heterogeneous devices. However, IoT devices are resource-constrained with energy and memory. Recently, Information-Centric Networking (ICN) has been established as a best communication paradigm for future internet, particularly in IoT. Based on hierarchically structured names, ICN matches the application pattern of IoT systems and provides an efficient and intelligent communication paradigm for both IoT and AAL (IoT-AAL) technologies. In this work, we design an IoT architecture for AAL via ICN approach which will effectively improve the performance of communication between the heterogeneous devices and services integrated in IoT-AAL.

In this work, a secure wireless sensor network (WSN) for the surveillance, monitoring and protection of critical infrastructures was developed. To guarantee the security of the system, the main focus was the implementation of a unique security concept, which includes both security on the communication level, as well as mechanisms that ensure the functional safety during its operation. While there are many theoretical approaches in various subdomains of WSNs—like network structures, communication protocols and security concepts—the construction, implementation and real-life application of these devices is still rare. This work deals with these aforementioned aspects, including all phases from concept-generation to operation of a secure wireless sensor network. While the key focus of this paper lies on the security and safety features of the WSN, the detection, localization and classification capabilities resulting from the interaction of the nodes’ different sensor types are also described.

Software Product Lines (SPLs) are families of related software systems that provide different combinations of features. Extensive research and application attest to the significant economical and technological benefits of employing SPL practices. However, there are still several challenges that remain open. Salient among them is reverse engineering SPLs from existing variants of software systems and their subsequent evolution. In this paper, we aim at sketching connections between research on these open SPL challenges and ongoing work on Genetic Improvement. Our hope is that by drawing such connections we can spark the interest of both research communities on the exciting synergies at the intersection of these subject areas.

Named Data Networking (NDN) is a promising Information-Centric future Internet architecture. Besides its recognized potentialities as a content retrieval solution in wired domains, NDN has been also recently considered as an enabling technology for the Internet of Things (IoT), thanks to its innovative features like named-based routing and in-network caching. In particular, the possibility of caching at intermediate nodes can be especially useful to reduce the retrieval delay, and limit the network traffic and the load on data producer. However, unlike traditional Internet contents, IoT data are typically transient and periodically refreshed by the producer. At the same time, unlike Internet routers, IoT devices can be resource-constrained, with limitations in terms of energy, storage and processing capabilities. Therefore, caching algorithms designed for (intransient) Internet traffic and Internet routers do not well suit IoT domains. In this paper, we consider a wireless NDN-IoT network and propose a novel distributed probabilistic caching strategy that relies on the freshness of data and on potentially constrained capabilities of devices (energy level and storage capacity). The proposed solution has been evaluated through simulations with ndnSIM and results show that it outperforms traditional NDN caching mechanisms in terms of data retrieval and network energy efficiency.

Software Product Lines (SPLs) are families of related software systems distinguished by the set of features each one provides. Over the past decades SPLs have been the subject of extensive research and application both in academia and industry. SPLs practices have proven benefits such as better product customization and reduced time to market. Testing SPLs pose additional challenges stemming from the typically large number of product variants which make it infeasible to test every single one of them. In recent years, there has been an extensive research on applying Combinatorial Interaction Testing (CIT) for SPL testing. In this paper we present the first systematic mapping study on this subject. Our research questions aim to gather information regarding the techniques that have been applied, the nature of the case studies used for their evaluation, and what phases of CIT have been addressed. Our goal is to identify common trends, gaps, and opportunities for further research and application.

One of today’s major problems in the field of e‐learning is that the creation of high‐quality content is still rather time consuming and expensive. In the past, many efforts have been made to produce educational content on the fly, but the results were mainly static blocks of recorded lecture lacking sophisticated navigation facilities. Facing this challenge the authors developed the concept of hyper‐presentations. During the live presentation content‐ and time‐based metadata is captured and stored in a lightweight and player‐independent format. With this metadata powerful navigation facilities like real time navigation and full text search in audio or video data can be generated automatically. This improves flexibility and interoperability of technical solutions, which are both key factors in the emerging rapid e‐learning market.