Real-Time Containers: A Survey

Container-based virtualization has gained a significant importance in a deployment of software applications in cloud-based environments. The technology fully relies on operating system features and does not require a virtualization layer (hypervisor) that introduces a performance degradation. Container-based virtualization allows to co-locate multiple isolated containers on a single computation node as well as to decompose an application into multiple containers distributed among several hosts (e.g., in fog computing layer). Such a technology seems very promising in other domains as well, e.g., in industrial automation, automotive, and aviation industry where mixed criticality containerized applications from various vendors can be co-located on shared resources. However, such industrial domains often require real-time behavior (i.e, a capability to meet predefined deadlines). These capabilities are not fully supported by the container-based virtualization yet. In this work, we provide a systematic literature survey study that summarizes the effort of the research community on bringing real-time properties in container-based virtualization. We categorize existing work into main research areas and identify possible immature points of the technology

AORTA: Advanced Offloading for Real-time Applications

We are currently witnessing the second wave of cloud services that go beyond web storefronts and IT systems, aiming for digitalization of industrial systems. Automation and time-sensitive systems are now taking their first steps toward the cloud. The AORTA project aims to facilitate this transition by providing key technology components needed for real-time services running in the cloud. The ambition is to support a future robotics ecosystem that enables a new level of flexible productivity in industrial production. AORTA will develop technologies that allow offloading of real-time services/functions to the edge and cloud. We will build upon recent advances in 5G, cloud, and networking technologies. The AORTA framework will support a fluid compute model where functionality will be dynamically deployed locally, in the edge, or in the cloud and support integration and real-time performance irrespective of where it executes. Results of the project will be demonstrated in a real-world robotics manufacturing and construction scenarios operating via a 5G network with real-time edge and large-scale cloud service. The AORTA technologies will provide opportunities for automation enterprises and system integrators by adding real-time capabilities needed to evolve beyond the currently closed ecosystem. They will also add value to telecom providers and operators that may host these new automation services in addition to their current portfolio

Multi-Hop Real-Time Communication over Switched Ethernet Technology

Switched Ethernet technology has been introduced to be exploited in real-time communication systems due to its features such as its high throughput and wide availability, hence being a cost-effective solution. Many real-time switched Ethernet protocols have been developed, preserving the profits of traditional Ethernet technology, to overcome the limitations imposed by using commercially available (COTS) switches. These limitations mainly originate from the non-deterministic behavior of the Ethernet switches inherent in the use of FIFO queues and a limited number of priority levels.   In our research we focus on two particular real-time communication technologies, one based on COTS Ethernet switches named the FTT-SE architecture and the other using a modified Ethernet switch called the HaRTES architecture. Both architectures are based on a master-slave technique supporting different and temporally isolated traffic types including real-time periodic, real-time sporadic and non-real-time traffic. Also, they provide mechanisms implementing adaptivity as a response to the requirements imposed by dynamic real-time applications. Nevertheless, the two mentioned architectures were originally developed for a simple network consisting of a single switch, and they were lacking support for multi-hop communication. In industrial applications, multi-hop communication is essential as the networks comprise a high number of nodes, that is far beyond the capability of a single switch.   In this thesis, we study the challenges of building multi-hop communication using the FTT-SE and the HaRTES architectures. We propose different architectures to provide multi-hop communication while preserving the key characteristics of the single-switch architecture such as timeliness guarantee, resource efficiency, adaptivity and dynamicity. We develop a response time analysis for each proposed architecture and we compare them to assess their corresponding benefits and limitations. Further, we develop a simulation tool to evaluate the solutions

Real-Time Communication over Switched Ethernet with Resource Reservation

Due to the need for advanced computer-controlled functionality in distributed embedded systems the requirements on network communication are becoming overly intricate. This dissertation targets the requirements that are concerned with real-time guarantees, run-time adaptation, resource utilization and flexibility during the development. The Flexible Time-Triggered Switched Ethernet (FTT-SE) and Hard Real-Time Ethernet Switching (HaRTES) network architectures have emerged as two promising solutions that can cater for these requirements. However, these architectures do not support multi-hop communication as they are originally developed for single-switch networks. This dissertation presents a fundamental contribution in multi-hop real-time communication over the FTT-SE and HaRTES architectures targeting the above mentioned requirements. It proposes and evaluates various solutions for scheduling and forwarding the traffic through multiple switches in these architectures. These solutions preserve the ability of dynamic adaptation without jeopardizing real-time properties of the architectures. Moreover, the dissertation presents schedulability analyses for the timeliness verification and evaluation of the proposed solutions as well as several protocols to support run-time adaptation in the multi-hop communication. Finally, the work led to an end-to-end resource reservation framework, based on the proposed multi-hop architectures, to support flexibility during the development of the systems. The efficiency of the proposed solutions is evaluated on various case studies that are inspired from industrial systems

Extending FTT-SE protocol for Multi-Master/Multi-Slave Networks

Ethernet Switches are widely used in real-time distributed systems as a solution to guarantee the real-time behavior in communication. In this solution there are still some limitations which are the important obstacles obtaining timeliness in the network. These limitations are the limited number of priority levels as well as the possibility of memory overruns with consequent messages. The mentioned limitations can be eliminated using a master/slave technique along with FTT paradigm. The FTT-SE protocol which is a technique based on the master/slave and FTT methods was proposed to overcome the mentioned limitations. However, the FTT-SE protocol has been investigated for a small network architecture with a single switch and master node. Extension of this solution to larger networks is still an open issue. Three different architectures were suggested to scale the FTT-SE to large scale network. In this thesis we propose a solution that extends the FTT-SEprotocol while keeping the real-time behavior of the network. In this solution, we divided the network into a set of sub-networks, each contains one switch, set of slave nodes and one master node that connected to the associated switch in the network. Moreover, the switches are connected together directly without gateways and form a tree topology network. The solution includes both synchronous and asynchronous traffic in the network. We also show that the timeliness of the traffic can still be enforced. Moreover, to validate the solution we have designed and implemented a simulator based on the Matlab/Simulink which is a tool to evaluate different network architecture using Simulink blocks. All transmission can be visualized by the ordinary Scope block in the Simulink. Moreover, the end-to-end delay for all messages is calculated after the simulation running to show the response time of the network. Furthermore, the response time analysis is done for both synchronous and asynchronous messages in this thesis according to the proposed solution. The results from simulation and the analysis are compared together to validate the investigations

Support for Hierarchical Scheduling in FreeRTOS

This paper presents the implementation of a HierarchicalScheduling Framework (HSF) on an open sourcereal-time operating system (FreeRTOS) to support the temporalisolation between a number of applications, on a single processor.The goal is to achieve predictable integration and reusability ofindependently developed components or applications. We presentthe initial results of the HSF implementation by running it onan AVR 32-bit board EVK1100. The paper addresses the fixed-priority preemptive schedulingat both global and local scheduling levels. It describes the detaileddesign of HSF with the emphasis of doing minimal changes tothe underlying FreeRTOS kernel and keeping its API intact.Finally it provides (and compares) the results for the performancemeasures of idling and deferrable servers with respect to theoverhead of the implementation.Submitted to 16th IEEE International Conference on Emerging Technologies and Factory automation (ETFA'11) ©2011 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE."</p

Supporting End-to-end Data-propagation Delay Analysis for TSN Networks

End-to-end data-propagation delay analysis allows verification of important timing constraints, such as age and reaction, that areoften specified on chains of tasks and messages in real-time systems.We identify that the existing analysis does not support distributed taskchains that include the Time-Sensitive Networking (TSN) messages. Tothis end, this paper extends the existing analysis to allow the end-to-endtiming analysis of distributed task chains that include TSN messages.The extended analysis supports all types of traffic in TSN, includingthe Scheduled Traffic (ST), Audio Video Bridging (AVB), and BestEffort (BE) traffic. Furthermore, the extended analysis accounts for thesynchronization among the end stations that are connected via TSN.The applicability of the analysis is demonstrated using an automotiveapplication case study.

An independent yet efficient analysis of bandwidth reservation for credit-based shaping

Ethernet TSN is an upcoming communication standard for industrial distributed embedded systems with high demands on bandwidth and traffic delay. In this paper, we present and prove an improved analysis to determine bandwidth reservations for credit based shapers in a single Ethernet TSN switch. We compare this new analysis, which is based on eligible intervals, to the state-of-the-art bandwidth reservation analysis based on busy periods through experiments. Despite its low complexity and the independence of the knowledge of the interfering traffic, the results show an improvement of efficiency, i.e., a decrease of the required bandwidth, for the new analysis

Supporting End-to-end Data-propagation Delay Analysis for TSN Networks

End-to-end data-propagation delay analysis allows verification of important timing constraints, such as age and reaction, that areoften specified on chains of tasks and messages in real-time systems.We identify that the existing analysis does not support distributed taskchains that include the Time-Sensitive Networking (TSN) messages. Tothis end, this paper extends the existing analysis to allow the end-to-endtiming analysis of distributed task chains that include TSN messages.The extended analysis supports all types of traffic in TSN, includingthe Scheduled Traffic (ST), Audio Video Bridging (AVB), and BestEffort (BE) traffic. Furthermore, the extended analysis accounts for thesynchronization among the end stations that are connected via TSN.The applicability of the analysis is demonstrated using an automotiveapplication case study.