Data Streams - an Analysis of the Interactions Between Real-Time Tasks

Calha, Mario; Fonseca, J.

doi:10.1109/etfa.2005.1612548

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…The application composer must then deduce the appropriate offsets, for example, using the techniques proposed in [2]. Notice, however, that either the response time analysis and the generation of the required offsets are beyond the scope of this work.…”

Section: Figure 3 a Transaction And Its Timelinementioning

confidence: 98%

“…Alternatively, the scheduler may trigger just the message transmissions while the associated tasks are triggered by the reception of these, using callback functions. In any case, the application transactions are triggered by the central scheduler, which resides in a network component, and thus we call this a networkcentric approach [2,14].…”

Section: Temporal Model Of An Applicationmentioning

confidence: 99%

“…1(a), which is executed periodically. A corresponding transaction (or data stream as in [2]) is then defined as the sequence of task executions and message transmissions between the triggering of the first producer and termination of the last consumer involved in an application. Typically, all tasks and messages in a transaction share the same period but not necessarily, such as in multirate control systems in which inner loops execute at rates that are integer multiples of a lower rate at which an outer loop executes.…”

Section: Application Modelmentioning

confidence: 99%

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An Architecture to Support Dynamic Service Composition in Distributed Real-Time Systems

Estevez-Avres

Almeida

Garcia-Vails

et al. 2007

10th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC'07)

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Recently, new trends in application development for distributed platforms, such as the composable services model, attempt to provide more flexibility in system design, deployment and execution. Such trends, and particularly the referred composable services model, can also be beneficial in real-time distributed embedded systems, also providing a means to support more adaptive behaviors, reacting to the execution environment or coping with system reconfiguration. This paper explores a relatively new direction, which is the extension of the service-based model to dynamic, i.e. at run-time, composition in real-time distributed environments, in order to support the level of flexibility and adaptibility referred above. The paper proposes an architecture to support such dynamic service composition that is based on the Flexible Time Triggered communication paradigm (FTT).To achieve the desired goal, we also redefine the concepts of service and service-based application in the concept of the FTT paradigm. Finally, we show experimental results obtained with a prototype implementation of the proposed architecture that confirm its feasibility and good temporal behavior.

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Section: Figure 3 a Transaction And Its Timelinementioning

confidence: 98%

Section: Temporal Model Of An Applicationmentioning

confidence: 99%

Section: Application Modelmentioning

confidence: 99%

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An Architecture to Support Dynamic Service Composition in Distributed Real-Time Systems

Estevez-Avres

Almeida

Garcia-Vails

et al. 2007

10th IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC'07)

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“…One interesting aspect is that the time-triggered model allows decoupling all active resources in the system, i.e., nodes and network, in a way that each one can be analysed separately and appropriate off-sets can be derived to control the end-to-end latency of distributed transactions [6] [17]. Therefore, from this point on and for the sake of clarity we will refer to one task set executing on one node.…”

Section: System Model and Problem For-mulationmentioning

confidence: 99%

A dynamic scheduling approach to designing flexible safety-critical systems

Almeida

Fischmeister

Anand

et al. 2007

Proceedings of the 7th ACM &Amp; IEEE International Conference on Embedded Software - EMSOFT '07

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The design of safety-critical systems has typically adopted static techniques to simplify error detection and fault tolerance. However, economic pressure to reduce costs is exposing the limitations of those techniques in terms of efficiency in the use of system resources. In some industrial domains, such as the automotive, this pressure is too high, and other approaches to safety must be found, e.g., capable of providing some kind of fault tolerance but with graceful degradation to lower costs, or also capable of adapting to instantaneous requirements to better use the computational/communication resources. This paper analyzes the development of systems that exhibit such level of flexibility, allowing the system configuration to evolve within a well-defined space. Two options are possible, one starting from the typical static approach but introducing choice points that are evaluated only at runtime, and another one starting from an open systems approach but delimiting the space of possible adaptations. The paper follows the latter and presents a specific contribution, namely, the concept of local utilization bound, which supports a fast and efficient schedulability analysis for on-line resource management that assures continued safe operation. Such local bound is derived off-line for the specific set of possible configurations, and can be significantly higher than any generic non-necessary utilization bound such as the well known Liu and Layland's bound for RateMonotonic scheduling. Comments Postprint version. Published in ABSTRACTThe design of safety-critical systems has typically adopted static techniques to simplify error detection and fault tolerance. However, economic pressure to reduce costs is exposing the limitations of those techniques in terms of efficiency in the use of system resources. In some industrial domains, such as the automotive, this pressure is too high, and other approaches to safety must be found, e.g., capable of providing some kind of fault tolerance but with graceful degradation to lower costs, or also capable of adapting to instantaneous requirements to better use the computational/communication resources. This paper analyses the development of systems that exhibit such level of flexibility, allowing the system configuration to evolve within a well-defined space. Two options are possible, one starting from the typical static approach but introducing choice points that are evaluated only at runtime, and another one starting from an open systems approach but delimiting the space of possible adaptations. The paper follows the latter and presents a specific contribution, namely, the concept of local utilization bound, which supports a fast and efficient schedulability analysis for on-line resource management that assures continued safe operation. Such local bound is derived off-line for the specific set of possible configurations, and can be significantly higher than any generic non-necessary utilization bound such as the well known Liu and Layland's bound for Rate-Monotonic sche...

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