Felix Jonathan Oppermann

Process-based design and integration of wireless sensor network applications

Wireless Sensor and Actuator Networks (WSNs) are distributed sensor and actuator networks that monitor and control real-world phenomena, enabling the integration of the physical with the virtual world. They are used in domains like building automation, control systems, remote healthcare, etc., which are all highly process-driven. Today, tools and insights of Business Process Modeling (BPM) are not used to model WSN logic, as BPM focuses mostly on the coordination of people and IT systems and neglects the integration of embedded IT. WSN development still requires significant special-purpose, low-level, and manual coding of process logic. By exploiting similarities between WSN applications and business processes, this work aims to create a holistic system enabling the modeling and execution of executable processes that integrate, coordinate, and control WSNs. Concretely, we present a WSN-specific extension for Business Process Modeling Notation (BPMN) and a compiler that transforms the extended BPMN models into WSN-specific code to distribute process execution over both a WSN and a standard business process engine. The developed tool-chain allows modeling of an independent control loop for the WSN.

A Decade of Wireless Sensing Applications: Survey and Taxonomy

The popularity of low-power wireless sensors increased significantly in the last decade, triggering a golden era for wireless sensor network research and development. During the early years of the twenty-first century, wireless sensor network applications have evolved from small demonstrations with a lifetime of only a few hours to complete systems made up of hundreds of tiny wireless nodes deployed in a wide variety of settings, ranging from harsh and remote environments to residential buildings and clinical units. This survey gives an overview of the most relevant applications of wireless sensor network applications deployed during the last ten years, and classifies them using a novel taxonomy that aims to help identifying relevant programming constructs and run-time services. With more than 60 applications reviewed, ranging from military and civilian surveillance to tracking systems, from environmental and structural monitoring to home and building automation, from agriculture and industrial settings to health care, this survey will serve as a reference to guide researchers and system designers.

Towards business processes orchestrating the physical enterprise with wireless sensor networks

The industrial adoption of wireless sensor networks (WSNs) is hampered by two main factors. First, there is a lack of integration of WSNs with business process modeling languages and back-ends. Second, programming WSNs is still challenging as it is mainly performed at the operating system level. To this end, we provide makeSense: a unified programming framework and a compilation chain that, from high-level business process specifications, generates code ready for deployment on WSN nodes.

Design and compilation of an object-oriented macroprogramming language for wireless sensor networks

Wireless sensor network (WSN) programming is still largely performed by experts in a node-centric way using low-level languages such as C. Although numerous higher-level abstractions exist, each simplifying a specific aspect of distributed programming, real applications often require to combine multiple abstractions into a single program. Using current programming frameworks, this represents a difficult task. In previous work, we therefore defined a conceptual framework that facilitates abstraction composition by defining sound compositional rules among few fundamental abstraction categories. The framework is extensible: programmers can add new abstractions within the boundaries determined by the compositional rules. In this paper we describe the design of a language-called MPL-that instantiates this conceptual framework. To support the extensible nature of the framework, the language is object-oriented, which allows programmers to add new abstractions by inheriting from existing classes that implement predefined interfaces. We modeled the syntax after Java, to make it more palatable to inexperienced embedded programmers. Compared to Java, we modified the language to enable efficient execution on WSN devices. We designed and implemented a compiler that translates MPL language into executable C code, which spares the overhead of a virtual machine. By comparing MPL implementations against functionally-equivalent Contiki/C implementations of several benchmark applications, we determined that the performance overhead of MPL is limited, and yet the programming task is simplified.

Combining Business Process Variability and Software Variability Using Traceable Links

Nowadays, domains like Cyber-Physical Systems (CPS) and Internet of Things (IoT) are highly affected by short product cycles and high pricing pressure. Business Process oriented organizations are known to perform better in such flexible environments. However, especially industries which are focused on delivering low cost systems are facing big challenges if the according business processes are not aligned with the capabilities of the product. Consequently, development effort is spent for features which are never addressed by any business goal. With this work, we propose to use a combined variability management in order to create an integrated view on the product variability from an organizational point as well as from a technical view. Using this approach helps in order to identify business drivers as well as to establish a mature product line development.

Patterns to establish a secure communication channel

Nowadays, cyber-physical systems (CPS) are omnipresent in our daily lives and are increasingly used to process confidential data. While the variety of portable devices we use excessively at home and at work is steadily increasing, their security vulnerabilities are often not noticed by the user. Therefore, portable devices such as wearables are becoming more and more interesting for adversaries. Additionally, the increasing functionalities like internet capabilities, cameras, microphones, GPS trackers and other senor devices make them an interesting target for hacking. Furthermore, such CPS devices are often deployed in unsupervised and untrusted environments raising the question about privacy and security to a crucial topic. Thus, a robust and secure software design is required for the implementation of cryptographic communication protocols and encryption algorithms. In our opinion, Software-Patterns have proven to be an efficient way to support the development of such systems. Therefore, we will present patterns for solving the issue of Man-in-the-middle attacks. The presented patterns provide generic guidance on how to establish secure communication channels based on symmetric and / or asymmetric cryptography. Further, a selection graph is presented which helps to find the appropriate pattern in a specific context.

Increasing the Visibility of Requirements Based on Combined Variability Management

Nowadays, consumer-oriented industries like the Internet of Things, are highly affected by short product cycles and high pricing pressure. Agile and process-oriented organizations are known to perform better in such flexible environments. However, especially industries which are focused on delivering low cost systems are facing big challenges if the according Business Processes are not aligned with the capabilities of the product. Furthermore, non-functional requirements like safety and security are often not integrated in the early stages of a project, but later on added as a kind of extension, leading to a lower product maturity. With this work, we extend our framework for combined variability management in order to create an integrated view on the product variability from an organizational point, as well as from a technical view, including security requirements from the early development.

Automatic configuration of controlled interference experiments in sensornet testbeds

Experiments under controlled radio interference are crucial to assess the robustness of low-power wireless protocols. While tools such as JamLab augment existing sensornet testbeds with realistic interference, it remains an error-prone and time-consuming task to manually select the set of nodes acting as jammers and their individual transmit powers. We present an automated configuration approach based on simulated annealing to overcome this problem. A preliminary evaluation based on two testbeds shows that our approach can find near-optimal solutions within at most a few hours. We believe our approach can facilitate the widespread adoption of controlled interference experiments by the sensornet community.