P4CEP: Towards In-Network Complex Event Processing

In-network computing using programmable networking hardware is a strong trend in networking that promises to reduce latency and consumption of server resources through offloading to network elements (programmable switches and smart NICs). In particular, the data plane programming language P4 together with powerful P4 networking hardware has spawned projects offloading services into the network, e.g., consensus services or caching services. In this paper, we present a novel case for in-network computing, namely, Complex Event Processing (CEP). CEP processes streams of basic events, e.g., stemming from networked sensors, into meaningful complex events. Traditionally, CEP processing has been performed on servers or overlay networks. However, we argue in this paper that CEP is a good candidate for in-network computing along the communication path avoiding detouring streams to distant servers to minimize communication latency while also exploiting processing capabilities of novel networking hardware. We show that it is feasible to express CEP operations in P4 and also present a tool to compile CEP operations, formulated in our P4CEP rule specification language, to P4 code. Moreover, we identify challenges and problems that we have encountered to show future research directions for implementing full-fledged in-network CEP systems.Comment: 6 pages. Author's versio

In-network complex event processing using advanced data-plane programming

Event detection latency is an important aspect of complex event processing which could be improved significantly by utilizing the capabilities of networking devices, which already exist in computer networks. For this reason, this thesis presents a new language for expressing complex event detection rules along with P4CEP, a compiler which translates these rules into P4 code, which can be used for integrating complex event detection into the data-plane. P4CEP reads a CEP rule definition, builds a finite state machine for event detection and then converts the rules into P4 code and forwarding table entries. P4CEP was tested and evaluated with the Netronome SmartNIC and compared against the state-of-the-art CEP framework Apache Flink. In a simple test case and with the Netronome SmartNIC, an event detection latency of 18 µs was measured for P4CEP compared to 232 µs with Apache Flink, which is a 93% decrease in latency.Die Latenz der Ereigniserkennung ist ein wichtiger Aspekt der Verarbeitung komplexer Ereignisse (Complex Event Processing), der durch die Ausnutzung existierender Fähigkeiten von Netzwerkkomponenten verbessert werden kann. Aus diesem Grund wird in dieser Arbeit eine neue Sprache für das Ausdrücken von Regeln für die Erkennung komplexer Ereignisse und P4CEP, ein Compiler, der diese Sprache in P4 Code übersetzt, vorgestellt, womit die Erkennung komplexer Ereignisse in die Datenschicht (data-plane) des Netzwerks integriert werden kann. P4CEP liest eine Regeldefinition zur Erkennung komplexer Ereignisse in dieser Sprache ein, verarbeitet diese Definitionen weiter zu einem endlichen Automat und konvertiert diesen in P4 Code und Tabelleneinträge für die Weiterleitungstabellen des Switches. P4CEP wurde mit dem Netronome SmartNIC getestet, evaluiert und mit dem CEP System Apache Flink verglichen. In einem einfachen Vergleichsfall wurden 18 µs Latenz mit P4CEP und 232 µs mit Apache Flink gemessen, dies stellt eine Verringerung der Latenz um 93% dar

Design and implementation of privacy-preserving mechanisms for tracking Bluetooth Low Energy devices

Die Verfolgung eines mobilen Gerätes ist eine nützliche Möglichkeit für den alltäglichen Gebrauch, allerdings sollte diese Verfolgung nur befugten Personen möglich sein. Bluetooth Low Energy-Beacons bieten eine Möglichkeit dies zu implementieren ohne die Mobilität eines mobilen Geräts einzuschränken. Da BLE-Beacons sehr energieeffizient arbeiten können, ist es möglich ein solches Beacon für mehrere Monate oder Jahre zu betrieben ohne die Batterie wechseln zu müssen. In dieser Arbeit wird ein System vorgestellt und implementiert, das dem Besitzer eines BLE-Beacons die Verfolgung dieser Geräte ermöglicht, ohne dass Dritten diese Verfolgung auch möglich ist. Hierfür verwendet ein Beacon Pseudonyme, die sich periodisch ändern, ohne dass ein Angreifer das nächste Pseudonym vorhersagen kann, obwohl der Besitzer des Beacons hierzu in der Lage ist. Diese Pseudonyme werden von einem Sensornetz aus Smartphones empfangen und an einen zentralen Server weitergeleitet, welcher es dem Besitzer ermöglicht die Position des eigenen Beacons abzufragen. Um die Energieeffizienz der Beaconimplementierungen zu testen wurde der Energieverbrauch der Beacons gemessen. Hierbei wurde eine Laufzeit von ca. einem Jahr auf einer üblichen 3V Knopfzelle errechnet.Tracking a mobile device is a useful ability for day to day use. However, tracking the device should only be possible for people who are authorized to do so. Bluetooth Low Energy Beacons provide the means to do this without compromising the mobility of the device. Due to the low energy usage of BLE it is possible to operate a Beacon for multiple years without having to change the battery. This thesis presents and implements a system which allows the owner of a BLE beacon to track their devices without exposing this information to third parties. To do this it uses pseudonyms which change periodically to obfuscate the identity of a beacon. The used pseudonyms can be regenerated by the owner because only they posses the necessary information to do this. The BLE signals of the beacons containing the pseudonyms are received by a sensor net of smartphones which add their own position and relay this information to a central server which stores this data. This server allows the owner to retrieve the position of their beacon and track its movements. The energy efciency of the beacons was analyzed by measuring the energy consumption. This showed that a beacon could operate for up to one year on a typical 3 V button cell

Unraveling the differential impact of PAHs and dioxin-like compounds on AKR1C3 reveals the EGFR extracellular domain as a critical determinant of the AHR response.

Polycyclic aromatic hydrocarbons (PAHs), dioxin-like compounds (DLCs) and structurally-related environmental pollutants may contribute to the pathogenesis of various diseases and disorders, primarily by activating the aryl hydrocarbon receptor (AHR) and modulating downstream cellular responses. Accordingly, AHR is considered an attractive molecular target for preventive and therapeutic measures. However, toxicological risk assessment of AHR-modulating compounds as well as drug development is complicated by the fact that different ligands elicit remarkably different AHR responses. By elucidating the differential effects of PAHs and DLCs on aldo-keto reductase 1C3 expression and associated prostaglandin D2 metabolism, we here provide evidence that the epidermal growth factor receptor (EGFR) substantially shapes AHR ligand-induced responses in human epithelial cells, i.e. primary and immortalized keratinocytes and breast cancer cells. Exposure to benzo[a]pyrene (B[a]P) and dioxin-like polychlorinated biphenyl (PCB) 126 resulted in a rapid c-Src-mediated phosphorylation of EGFR. Moreover, both AHR agonists stimulated protein kinase C activity and enhanced the ectodomain shedding of cell surface-bound EGFR ligands. However, only upon B[a]P treatment, this process resulted in an auto-/paracrine activation of EGFR and a subsequent induction of aldo-keto reductase 1C3 and 11-ketoreduction of prostaglandin D2. Receptor binding and internalization assays, docking analyses and mutational amino acid exchange confirmed that DLCs, but not B[a]P, bind to the EGFR extracellular domain, thereby blocking EGFR activation by growth factors. Finally, nanopore long-read RNA-seq revealed hundreds of genes, whose expression is regulated by B[a]P, but not by PCB126, and sensitive towards pharmacological EGFR inhibition. Our data provide novel mechanistic insights into the ligand response of AHR signaling and identify EGFR as an effector of environmental chemicals