An increasing number of systems span from the data-center down to the micro-controller and need to smoothly operate across this continuum composed by extremely heterogeneous network technologies and computing platforms. Building these systems is quite challenging due to limitations of existing technological stacks. This paper introduces Zenoh a Pub/Sub-/Query protocol that unifies data at rest, data in motion and computations. Zenoh has been designed ground-up to address the needs of the cloud to micro-controller continuum. It has a minimal wire overhead of 5 bytes, it runs and perform on constrained as well as on high end networks and hardware.

Early Internet of Things(IoT) applications have been build around cloud-centric architectures where information generated at the edge by the "things" in conveyed and processed in a cloud infrastructure. These architectures centralise processing and decision on the data-centre assuming sufficient connectivity, bandwidth and latency. As applications of the Internet of Things extend to industrial and more demanding consumer applications, the assumptions underlying cloud-centric architectures start to be violated as for several of these applications connectivity, bandwidth and latency to the data-centre are a challenge. Fog and Mist computing have emerged as forms of "Cloud Computing" closer to the "Edge" and to the "Things" that should alleviate the connectivity, bandwidth and latency challenges faced by Industrial and extremely demanding Consumer Internet of Things Applications.

introduction Share on Introduction to special issue on Java technologies for real-time and embedded systems Authors: M. Teresa Higuera-Toledano Universidad Complutense de Madrid, Spain Universidad Complutense de Madrid, SpainView Profile , Doug Locke LC Systems Services Inc., USA LC Systems Services Inc., USAView Profile , Angelo Corsaro PrismTech Corporation, France PrismTech Corporation, FranceView Profile Authors Info & Claims ACM Transactions on Embedded Computing SystemsVolume 10Issue 1August 2010 Article No.: 1pp 1–4https://doi.org/10.1145/1814539.1814540Published:27 August 2010Publication History 0citation446DownloadsMetricsTotal Citations0Total Downloads446Last 12 Months6Last 6 weeks1 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my Alerts New Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

This paper studies the problem of realizing a common software clock among a large set of nodes without an external time reference (i.e., internal clock synchronization), any centralized control, and where nodes can join and leave the distributed system at their will. The paper proposes an internal clock synchronization algorithm which combines the gossip-based paradigm with a nature-inspired approach, coming from the coupled oscillators phenomenon, to cope with scale and churn. The algorithm works on the top of an overlay network and uses a uniform peer sampling service to fulfill each node's local view. Therefore, differently from clock synchronization protocols for small scale and static distributed systems, here, each node synchronizes regularly with only the neighbors in its local view and not with the whole system. An evaluation of the convergence speed and the synchronization error of the coupled-based internal clock synchronization algorithm has been carried out, showing how convergence time and the synchronization error depends on the coupling factor and the local view size. Moreover, the variation of the synchronization error with respect to churn and the impact of a sudden variation of the number of nodes have been analyzed to show the stability of the algorithm. In all these contexts, the algorithm shows nice performance and very good self-organizing properties. Finally, we showed how the assumption on the existence of a uniform peer-sampling service is instrumental for the good behavior of the algorithm and how, in system models where network delays are unbounded, a mean-based convergence function reaches a lower synchronization error than median-based convergence functions exploiting the number of averaged clock values.

First International Workshop on Emerging Technologies for Next-generation GRID (

The real-time specification for Java (RTSJ) introduces a new memory model featuring some programming constraints that impede the "as-is" use of many well known design patterns. In this context, this paper describes and evaluates two design patterns, developed by the authors for distributed real-time Java software, that are able to overcome the limitations imposed by RTSJ. The first pattern, RTJ-leader-follower; is a RTSJ-compliant version of the well-known leader/follower pattern. The second pattern, called scoped tunnels, provides a new communication mechanism for RTSJ threads executing in different and incompatible memory areas, thus making possible the realization of the standard pattern half-sync/half-async for efficient network I/O handling. The paper presents both a qualitative and quantitative evaluation of these patterns, showing, above all, that they are able to provide a safe execution environment

More than 90 percent of all microprocessors are now used for real-time and embedded applications. The behavior of these applications is often constrained by the physical world. It is therefore important to devise higher-level languages and middleware that meet conventional functional requirements, as well as dependably and productively enforce real-time constraints. We provide two contributions to the study of languages and middleware for real-time and embedded applications. We first describe the architecture of jRate, which is an open-source ahead-of-time-compiled implementation of the RTSJ middleware. We then show performance results obtained using RTJPerf, which is an open-source benchmarking suite that systematically compares the performance of RTSJ middleware implementations. We show that, while research remains to be done to make RTSJ a bullet-proof technology, the initial results are promising. The performance and predictability of JRate provides a baseline for what can be achieved by using ahead-of-time compilation. Likewise, RTJPerf enables researchers and practitioners to evaluate the pros and cons of RTSJ middleware systematically as implementations mature.