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A survey on standards for real-time distribution middleware

This survey covers distribution standards oriented to the development of distributed real-time systems. Currently, there are many distribution standards that provide a wide and different set of real-time facilities to control the temporal aspects of applications. Besides giving a general overview of these standards, we describe the real-time mechanisms proposed by each standard to manage both processor and network resources, discuss whether the available facilities are sufficient to guarantee determinism throughout the whole application, and identify a set of features and deployment options that would be desirable in any real-time distribution middleware regardless of its distribution model and standard. The survey identifies open issues and key challenges for future research.

Real-Time Distribution Middleware from the Ada Perspective

Standards for distribution middleware sometimes impose restrictions and often allow the implementations to decide on aspects that are fundamental to the correct and efficient behaviour of the applications using them, especially when these applications have real-time requirements. This work presents a study of two standard approaches for distribution middleware that can be used from Ada applications: RT-CORBA, and the Distributed Systems Annex (DSA) of Ada. The study focuses on the problems associated with the real-time behaviour of some implementations of these approaches, and on possible solutions that can be derived from our experience with Ada implementations. Moreover, the paper considers the problem of integration of the distribution middleware with a new generation of scheduling mechanisms based on contracts.

Distributed architecture for developing mixed-criticality systems in multi-core platforms

Abstract Partitioning is a widespread technique that enables the execution of mixed-criticality applications in the same hardware platform. New challenges for the next generation of partitioned systems include the use of multiprocessor architectures and distribution standards in order to open up this technique to a heterogeneous set of emerging scenarios (e.g., cyber-physical systems). This work describes a system architecture that enables the use of data-centric distribution middleware in partitioned real-time embedded systems based on a hypervisor for multi-core, and it focuses on the analysis of the available architectural configurations. We also present an application-case study to evaluate and identify the possible trade-offs among the different configurations.

Modeling the QoS parameters of DDS for event-driven real-time applications

We propose an approach to enable the early schedulability analysis of real-time applications distributed with the DDS standard.Fault tolerance and real-time features of DDS are represented using the MARTE end-to-end flow model.We identify the existence of complex interactions among DDS entities that may influence the real-time modeling of applications.We analyze and evaluate a case-study from the automotive domain to demonstrate the validity of the approach.Further step toward the integration of DDS into model-driven development processes. 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 represent them using the real-time end-to-end flow model defined by the MARTE standard. We also present an application-case study to illustrate the use and modeling of DDS in next-generation distributed real-time systems.

Experience with the Integration of Distribution Middleware into Partitioned Systems

This paper proposes an architecture to enable the use of distribution middleware in partitioned systems based on a hypervisor. Partitioning is a widespread technique used in the development of high-integrity systems. In this kind of critical systems, software has to be as simple as possible in order to ease certification, and as the use of distribution middleware increases complexity, it has been avoided by developers. However, partitioning allows applications with different levels of criticality (mixed-criticality) to be executed in the same system. We propose the use of distribution middleware for the development of those applications with lower level of criticality, and present an experience in porting middleware based on CORBA and Ada DSA (Distributed Systems Annex) standards to the hypervisor XtratuM.

Model-Driven Development of High-Integrity Distributed Real-Time Systems Using the End-to-End Flow Model

Building High-integrity Distributed Real-Time (HDRT) systems requires a rigorous methodology to assist in the design and development of verifiable software. This paper describes an approach based on the Model-Driven Engineering (MDE) paradigm to ease the automatic generation of HDRT applications from high-level system models. Since those applications must be amenable to stringent timing analysis, such as the determination of worst-case execution time or schedulability analysis, we present the integration of a set of timing analysis tools with a toolset for MDE. In addition, this paper explores a new approach to integrating the real-time end-to-end flow model with the automatic generation of Raven scar-compliant source code in distribution middleware.

Enabling Data-Centric Distribution Technology for Partitioned Embedded Systems

Modern complex embedded systems are evolving into mixed-criticality systems in order to satisfy a wide set of non-functional requirements such as security, cost, weight, timing or power consumption. Partitioning is an enabling technology for this purpose, as it provides an environment with strong temporal and spatial isolation which allows the integration of applications with different requirements into a common hardware platform. At the same time, embedded systems are increasingly networked (e.g., cyber-physical systems) and they even might require global connectivity in open environments so enhanced communication mechanisms are needed to develop distributed partitioned systems. To this end, this work proposes an architecture to enable the use of data-centric real-time distribution middleware in partitioned embedded systems based on a hypervisor. This architecture relies on distribution middleware and a set of virtual devices to provide mixed-criticality partitions with a homogeneous and interoperable communication subsystem. The results obtained show that this approach provides low overhead and a reasonable trade-off between temporal isolation and performance.

Handling heterogeneous partitioned systems through ARINC-653 and DDS

Many cyber-physical systems in the avionics domain are mission- or safety-critical systems. In this context, standard distribution middleware has recently emerged as a potential solution to interconnect heterogeneous partitioned systems, as it would bring important benefits throughout the software development process. A remaining challenge, however, is reducing the complexity associated with current distribution middleware standards which leads to prohibitive certification costs. To overcome this complexity, this work explores the use of the DDS distribution middleware 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. We present and discuss a set of feasible system architectures to combine DDS and ARINC-653 standards as a solution to the future development of heterogeneous mixed-criticality systems.We analyse the integration of DDS and ARINC-653 by identifying the issues that may compromise the integration of both standards, and we also propose solutions to address them.We analyze and evaluate a case-study from the avionics domain to demonstrate the validity of the approach.The approach represents a further step towards the development of a safety-critical profile for DDS.

AFDX Emulator for an ARINC-Based Training Platform

AFDX (Avionics Full Duplex Switched Ethernet) is a standard communication network for avionics based on Ethernet links and special-purpose switches. This paper proposes an AFDX emulator based on standard Ethernet hardware (cards and switches) to build a low cost AFDX network for training or basic research purposes. We also propose the integration of the emulator within an ARINC-653 platform to allow the development of real-time Ada applications. Finally, a performance evaluation has been done in order to show the usability of the emulator.

Managing transactions in flexible distributed real-time systems

This paper describes the design and implementation of the Distributed Transaction Manager (DTM), a service that provides remote negotiation of contracts representing resource reservations in real-time distributed applications. We assume that there is an underlying middleware which can be used by the application to negotiate contracts locally: processor contracts have to be negotiated in the same processor where they will run, and network contracts have to be negotiated in a processing node connected to the specific network that will be used. In addition, the paper proposes the integration of the DTM in a distribution middleware based on CORBA and Ada’s Distributed Systems Annex (DSA) which supports advanced scheduling mechanisms based on contracts. The use of the distribution middleware enhances some implementation aspects of the DTM and provides new capabilities as, for example, routing messages through different networks.