Real-time modelling of DDS for event-driven applications

REACTION 2012. 1st International workshop on Real-time and distributed computing in emerging applications. December 4th, 2012, San Juan, Puerto Rico.The Data Distribution Service (DDS) standard defines a data-centric distribution middleware that supports the development of distributed real-time systems. To this end, the standard includes a wide set of configurable parameters to provide different degrees of Quality of Service (QoS). This paper presents an analysis of these QoS parameters when DDS is used to build reactive applications normally designed under an event-driven paradigm, and shows how to configure DDS to obtain predictable applications suitable to apply traditional schedulability analysis techniques.This work has been funded in part by the Spanish Government under grant number TIN2011-28567-C03-02 (HI-PARTES)

A MDE-based optimisation process for Real-Time systems

The design and implementation of Real-Time Embedded Systems is now heavily relying on Model-Driven Engineering (MDE) as a central place to define and then analyze or implement a system. MDE toolchains are taking a key role as to gather most of functional and not functional properties in a central framework, and then exploit this information. Such toolchain is based on both 1) a modeling notation, and 2) companion tools to transform or analyse models. In this paper, we present a MDE-based process for system optimisation based on an architectural description. We first define a generic evaluation pipeline, define a library of elementary transformations and then shows how to use it through Domain-Specific Language to evaluate and then transform models. We illustrate this process on an AADL case study modeling a Generic Avionics Platform

A practical solution for functional reconfiguration of real-time service based applications through partial schedulability

REACTION 2012. 1st International workshop on Real-time and distributed computing in emerging applications. December 4th, 2012, San Juan, Puerto Rico.Timely reconfiguration in distributed real-time systems is a complex problem with many sides to it ranging from system-wide concerns down to the intrinsic non-robust nature of the specific middleware software and the used programming techniques. In an completely open distributed system, it is not possible to achieve time-deterministic functional reconfiguration; the set of possible target configurations that the system can transition to could be extremely large threatening the temporal predictability of the reconfiguration process. Therefore, a set of bounds and limitations to the structure of systems and to their open nature need to be imposed. In this paper, we present the different sides of the problem of reconfiguration. We provide a solution for timely reconfiguration based on reducing the solution space of solutions of partially closed applications; we have enhanced the logic of a middleware for distributed soft real-time applications with the proposed technique. As a result, applications require a limited number of schedulability tests to search for the valid target configuration. We present some results on the actual reduction of the configuration space achieved by our middleware.This work has been partly supported by the iLAND project (ARTEMISJU 100026) funded by the ARTEMIS JTU Call 1 and the Spanish Ministry of Industry (www.iland-artemis.org), ARTISTDesign NoE (IST-2007- 214373) of the EU 7th Framework Programme, and by the Spanish national project REM4VSS (TIN 2011-28339)

Towards the integration of data-centric distribution technology into partitioned embedded systems

REACTION 2013. 2nd International Workshop on Real-time and distributed computing in emerging applications. December 3rd, 2013, Vancouver, Canada.This work proposes an architecture to enable the use of data-centric real-time distribution middleware in partitioned embedded systems based on a hypervisor. Partitioning is a technique that provides strong temporal and spatial isolation, thus allowing mixed-criticality applications to be executed in the same hardware. The proposed architecture not only enables transparent communication among partitions, but it also facilitates the interconnection between partitioned and nonpartitioned systems through distribution middleware. Preliminary results show that hypervisor technology provides low overhead and a reasonable trade-off between temporal isolation and performance.This work has been funded in part by the Spanish Government and FEDER funds under grant number TIN2011-28567-C03-02 (HIPARTES

Integration of Data Distribution Service and distributed partitioned systems

[EN] Avionics systems are complex and time-critical systems that are progressively adopting more flexible (though equally robust) architectural designs. Although a number of current avionics systems follow federated architectures, the Integrated Modular Avionics (IMA) paradign is becoming the dominant style in the more modern developments. The reason is that the IMA concept promotes modular designs where applications with different levels of criticality can execute in an isolated manner in the same hardware. This approach complies with the requirements of cost, safety, and weight of the avionics systems. FACE standard (Future Airborne Capability Environment) defines the architectural baseline for easing integration in avionics systems, including the communication functions across distributed components. As specified in FACE, middleware will be integrated into avionics systems to ease development of portable components that can interoperate effectively. This paper describes the usage of publish-subscribe middleware (precisely, DDS - Data Distribution Service for real-time systems) into a fully distributed partitioned system. We describe, from a practical point of view, the integration of the middleware communication overhead into the hierarchical scheduling (as compliant with ARINC 653) to allow the usage of middleware in the partitions. We explain the design of a realiable communication setting, exemplified on a distributed monitoring application in a partitioned environment. The obtained implementation results show that, given the stable communication overhead of the middleware, it can be integrated in the time windows of partitions.This work has been partly supported by the Spanish Ministry of Economy and Competitiveness through projects REM4VSS (TIN 2011-28339) and M2C2 (TIN2014-56158-C4-3-P).Garcia-Valls, M.; Domínguez-Poblete, J.; Eddine Touahria, I.; Lu, C. (2018). Integration of Data Distribution Service and distributed partitioned systems. Journal of Systems Architecture. 83:23-31. https://doi.org/10.1016/j.sysarc.2017.11.00123318

Data-centric distribution technology in ARINC-653 systems

REACTION 2014. 3rd International Workshop on Real-time and Distributed Computing in Emerging Applications. Rome, Italy. December 2nd, 2014.Standard distribution middleware has recently emerged as a potential solution to interconnect distributed systems in the avionics domain, as it would bring important benefits throughout the software development process. A remaining challenge, however, is reducing the complexity associated with current distribution standards which leads to prohibitive certification costs. To overcome this complexity, this work explores the use of the DDS distribution standard on top of a software platform based on the ARINC-653 specification. Furthermore, it discusses how both technologies can be integrated in order to apply them in mission and safety-critical scenarios.This work has been funded in part by the Spanish Government and FEDER funds under grant number TIN2011-28567-C03-02 (HIPARTES).Publicad

Design for Time-Predictability

A large part of safety-critical embedded systems has to satisfy hard real-time constraints. These need sound methods and tools to derive reliable run-time guarantees. The guaranteed run times should not only be reliable, but also precise. The achievable precision highly depends on characteristics of the target architecture and the implementation methods and system layers of the software. Trends in hardware and software design run contrary to predictability. This article describes threats to time-predictability of systems and proposes design principles that support time predictability. The ultimate goal is to design performant systems with sharp upper and lower bounds on execution times

An architectural approach with separation of concerns to address extra-functional requirements in the development of embedded real-time software systems

AbstractA large proportion of the requirements on embedded real-time systems stems from the extra-functional dimensions of time and space determinism, dependability, safety and security, and it is addressed at the software level. The adoption of a sound software architecture provides crucial aid in conveniently apportioning the relevant development concerns. This paper takes a software-centered interpretation of the ISO 42010 notion of architecture, enhancing it with a component model that attributes separate concerns to distinct design views. The component boundary becomes the border between functional and extra-functional concerns. The latter are treated as decorations placed on the outside of components, satisfied by implementation artifacts separate from and composable with the implementation of the component internals. The approach was evaluated by industrial users from several domains, with remarkably positive results

Development of real-time and mixed criticality distributed systems through the DDS standard

El uso de middleware de distribución facilita la programación de sistemas distribuidos de tiempo real heterogéneos, y por extensión también puede facilitar la generación automática de código como parte de una estrategia de desarrollo basada en modelos. Sin embargo, esta clase de middleware presenta una complejidad añadida que dificulta su uso en sistemas con ciertos requisitos de criticidad o de tiempo real. En este trabajo se hace una revisión de algunos estudios previos en los que se muestra la posibilidad de utilizar un middleware de distribución centrado en los datos (DDS, Data Distribution Service) para la integración de aplicaciones con criticidad mixta en sistemas distribuidos.The use of distribution middleware facilitates the programming of heterogeneous real-time distributed systems, and it can also facilitate the automatic generation of source code when integrated as a part of a general MDE (Model-Driven Engineering) strategy. However, the complexity usually associated with distribution middleware puts a burden on the development of applications with hard real-time requirements or high levels of criticality. This paper gathers a set of previous works to present an overview on how a data-centric distribution middleware (DDS, Data Distribution Service) could be used in distributed applications with mixed criticality and real-time requirements. © 2018 Elsevier Doyma. All rights reserved.Este trabajo ha sido financiado en parte por el Gobierno de España en el proyecto TIN2014-56158-C4-2-P (M2C2)