Content-based Publish/Subscribe in Software-defined Networks

With SDN, content-based publish/subscribe can be implemented on the network layer instead of using an application layer broker network. We present two methods realizing notification distribution with OpenFlow and P4, respectively

P4-programmable Data Plane for Content-based Publish/Subscribe

The domain-specific programming language P4 enables developers to specify how data plane devices (e.g., switches, routers) process packets. This opens up novel opportunities for efficient information dissemination at the network layer drastically reducing notification delays compared to applicationlayer publish/subscribe using broker overlay networks. In this paper, we present three different strategies that use P4 to realize content-based publish/subscribe. We start with a source routing strategy that is, then, improved to exploit and adapt a preinstalled forwarding tree by adding or removing branches if required. The most advanced strategy enables multiple forwarding trees to be dynamically stitched and adapted as needed

Realtime Publish/Subscribe for the Industrial Internet of Things

Publish/subscribe communication offers outstanding flexibility, but lacks the predictability required for guaranteeing (hard) realtime constraints in industrial environments such as future smart factories. In this paper, we review existing publish/ subscribe systems, identify their shortcomings, and derive research objectives for a converged realtime network infrastructure for the Industrial Internet of Things (IIoT) that is based on publish/subscribe and Software-Defined Networking (SDN)

Fast Publish/Subscribe Using Linux eBPF

In recent years, the requirements for publish/subscribe systems have changed enormously. Mainly, this is due to the vastly increasing number of smart objects, services, and apps being connected to the cloud and their growing demand for bandwidth and realtime message processing. Unfortunately, many publish/subscribe systems are hardly able to handle both necessary and available data rates when being built on conventional network stacks that suffer from significant system overhead. In this paper, we present a novel architecture for fast publish/subscribe that consists of an edge broker for preprocessing notifications and a cloud broker that leverages eBPF to efficiently process network packages and speed up notification delivery. We address limitations of eBPF, discuss different filter options, and quantify the achievable performance. The evaluation confirms a significant performance improvement of the eBPF-enabled cloud broker when compared to a conventional implementation

REBECA – eine autonome Publish/Subscribe Middleware

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively

Simulation model for energy consumption and acoustic underwater communication of autonomous underwater vehicles

Recently, cooperative autonomous underwater vehicles (AUVs) have been deployed in application areas such as surveillance and protection of maritime infrastructures for inspection and monitoring purposes. These cooperative methodologies require wireless transmission of data between the different AUVs operating in the underwater environment. Communication over ranges exceeding 100 m exclusively relies on underwater acoustic communication. However, the propagating acoustic waves suffer from several challenges due to the presence of path loss, multi-path propagation, the slow and variant propagation speed, background noise, and Doppler distortion. Since the power supply of the AUVs is limited, communication must be very energy efficient and energy constraints have to be known to be able to plan the mission of AUVs. Due to the difficulties of real experiments, the modeling and simulation of the energy consumption and underwater acoustic communication play an essential role in studying and developing these systems. We provide a modular simulation model for the energy consumption and acoustic underwater communication of AUVs implemented in the network simulator OMNeT++ using the INET framework. More specifically, we extend several INET modules in such a way as to reflect the characteristics of AUVs and underwater communication. We study and analyze the AUVs’ energy consumption and dependence of the message quality on different properties such as those mentioned above

A Simulation Model for Investigating Clock Synchronization Issues in Time-Sensitive Networks

The IEEE 802.1 Time-Sensitive Networking (TSN) task force has set guidelines for IEEE 802.3 networks allowing deterministic realtime communication over Ethernet. To execute deterministic time-triggered scheduling operations, the network nodes need to be synchronized. One application of time synchronization is distributed data acquisition for the Wendelstein 7-X nuclear fusion experiment. Both the system control and the scientific evaluation of the experiments need measurement timestamps with accuracies in the nanosecond range. The TSN standard IEEE 802.1AS has specified the generalized Precision Time Protocol (gPTP) which executes the synchronization process. However, there are some issues that are not addressed in the standard such as the impact of clock skew and drift of network nodes on the number of resynchronizations needed to maintain the required synchronization accuracy. This paper introduces an OMNeT++ simulation model, which can be used to investigate clock synchronization issues in time-sensitive networks

Engineering von Publish/Subscribe-Systemen und ereignisgetriebenen Anwendungen

Publish/subscribe systems provide a versatile basis for building distributed event-based infrastructures. Components communicate by publishing notifications about occurred events and by subscribing to those notifications of interest. In this thesis, we develop structuring means to modularly design and engineer large-scale event-based infrastructures. In particular, we present a composable architecture for publish/subscribe brokers, a scoping concept to limit the forwarding of notifications, and corresponding programming abstractions for event-driven applications.Publish/Subscribe-Systeme bieten eine flexible Grundlage zur Realisierung ereignisbasierter Infrastrukturen. Komponenten kommunizieren miteinander durch die Veröffentlichung von Notifikationen über aufgetretende Ereignisse und die Subskription der für sie relevanten Notifikationen. In dieser Arbeit werden strukturelle Abstraktionen für den modularen Entwurf und den Betrieb großer ereignisbasierter Infrastrukturen entwickelt. Es werden eine komponierbare Broker-Architektur, ein Scope-Konzept für Notifikationen und entsprechende Programmierabstraktionen für Applikationen vorgestellt

Michael A. Jaeger ∗ Self-Organizing Broker Topologies for Publish/Subscribe Systems

Distributed publish/subscribe systems are usually deployed on top of an overlay network that enables complex routing strategies implemented in the application layer. Up to now, only little effort has been spent on the design of the broker overlay network assuming that it is either static or manually administered. As publish/subscribe systems are increasingly targeted at dynamic environments where client behavior and network characteristics vary over time, static overlay networks lead to suboptimal performance. In this paper, we present a self-organizing broker overlay infrastructure that adapts dynamically to achieve a better efficiency on both, the application and the network layer. This is obtained by taking network metrics as well as notification traffic into account