This paper provides two contributions to the study of developing and applying domain-specific modeling languages (DSMLS) to distributed real-time and embedded (DRE) systems – particularly those systems using standards-based QoS-enabled component middleware. First, it describes the Platform-Independent Component Modeling Language (PICML), which is a DSML that enables developers to define component interfaces, QoS parameters and software building rules, and also generates descriptor files that facilitate system deployment. Second, it applies PICML to an unmanned air vehicle (UAV) application portion of an emergency response system to show how PICML resolves key component-based DRE system development challenges. Our results show that the capabilities provided by PICML – combined with its design- and deployment-time validation capabilities – eliminates many common errors associated with conventional techniques, thereby increasing the effectiveness of applying QoS-enabled component middleware technologies to the DRE system domain.

Abstract. We propose a mathematical framework to deal with the composition of heterogeneous reactive systems. Our theory allows to establish theorems, from which design techniques can be derived. We illustrate this by two cases: the deployment of synchronous designs over GALS architectures, and the deployment of synchronous designs over the so-called Loosely Time-Triggered Architectures. 1

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Benefits of high-level modeling and analysis are significantly enhanced if code can be generated automatically from a model such that the correspondence between the model and the code is precisely understood. For embedded control software, hybrid systems is an appropriate modeling paradigm because it can be used to specify continuous dynamics as well as discrete switching between modes. Establishing a formal relationship between the mathematical semantics of a hybrid model and the actual executions of the corresponding code is particularly challenging due to sampling and switching errors. In this paper, we describe an approach to compile the modeling language Charon that allows hierarchical specifications of interacting hybrid systems. We show how to exploit the semantics of Charon to generate code from a model in a modular fashion, and identify su#cient conditions on the model that guarantee the absence of switching errors in the compiled code. The approach is illustrated by compiling a model for coordinated motion of legs for walking onto Sony's AIBO robot.

Abstract. Model-Integrated Computing (MIC) is an approach to Model-Driven Architecture (MDA), which has been developed primarily for embedded systems. MIC places strong emphasis on the use of domain-specific modeling languages (DSML-s) and model transformations. A metamodeling process facilitated by the Generic Modeling Environment (GME) tool suite enables the rapid and inexpensive development of DSML-s. However, the specification of semantics for DSML-s is still a hard problem. In order to simplify the DSML semantics, this paper discusses semantic anchoring, which is based on the transformational specification of semantics. Using a mathematical model, Abstract State Machine (ASM), as a common semantic framework, we have developed formal operational semantics for a set of basic models of computations, called semantic units. Semantic anchoring of DSML-s means the specification of model transformations between DSML-s (or aspects of complex DSML-s) and selected semantic units. The paper describes the semantic anchoring process using the meta-programmable MIC tool suite. 1

Embedded system design is inherently domain specific and typically model driven. As a result, design methodologies like OMG’s model driven architecture (MDA) and model integrated computing (MIC) evolved to support domain specific modeling languages (DSMLs). The success of the DSML approach has encouraged work on the heterogeneous composition of DSMLs, model transformations between DSMLs, approximations of formal properties within DSMLs, and reuse of DSML semantics. However, in the effort to produce a mature design approach that can handle both the structural and behavioral semantics of embedded system design, many foundational issues concerning DSMLs have been overlooked. In this paper we present a formal foundation for DSMLs and for their construction within metamodeling frameworks. This foundation allows us to algorithmically decide if two DSMLs or metamodels are equivalent, if model transformations preserve properties, and if metamodeling frameworks have meta-metamodels. These results are key to building correct embedded systems with DSMLs.

Abstract — Distributed real-time embedded (DRE) systems often perform sequences of coordination and heterogeneous data manipulation tasks to meet specified goals. Autonomous operation of DRE systems in dynamic environments can benefit from the integrated operation of (1) a Spreading Activation Partial Order Planner (SA-POP) that combines task planning and scheduling in uncertain environments with (2) a Resource Allocation and Control Engine (RACE) middleware framework that integrates multiple resource management algorithms for (re)deploying and (re)configuring task sequence components in DRE systems. This paper demonstrates the effectiveness of the SA-POP decisiontheoretic planner and the RACE framework in managing and executing mission goals for a multi-satellite system application. Our results show how a dynamic planner that handles both scheduling and resource constraints is a key element in implementing autonomy for DRE systems. I.

Feedback control real-time scheduling (FCS) aims at satisfying performance specifications of real-time systems based on adaptive resource management. Existing FCS algorithms often rely on the existence of continuous control variables in real-time systems. A number of real-time systems, however, support only a finite set of discrete configurations that limit the adaptation mechanisms. This paper presents Hybrid Supervisory Utilization CONtrol (HySUCON) for scheduling such real-time systems. HySUCON enforces processor utilization bounds by managing the switchings between the discrete configurations. Our approach is based on a best-first-search algorithm that is invoked only if reconfiguration is necessary. Theoretical analysis and simulations demonstrate that the approach leads to robust utilization bounds for varying execution times. Experimental results demonstrate the algorithm performance for a representative application scenario. 1.

Conversion from floating-point to fixed-point formats is a necessary step in the design process of embedded systems and is traditionally performed manually. Automating this conversion process brings significant and much needed improvement in the efficiency of the design process. The fixify environment presented here fully automates the conversion process and comprises three optimization methods. The restricted-set full search algorithm is suited to designs that will be implemented on DSP cores and is, for such designs, guaranteed to find globally optimal solutions. On the other hand, the greedy search algorithm finds solution in the continuous search space and produces nearly optimal results, with the shortest required runtime. The branch-and-bound algorithm also works in the continuous search space and finds optimal solutions, but requires relatively long runtimes. 1.

We present a compositional theory of heterogeneous reactive systems. The approach is based on the concept of tags marking the events of the signals of a system. Tags can be used for multiple purposes from indexing evolution in time (time stamping) to expressing relations among signals like coordination (e.g., synchrony and asynchrony), and causal dependencies. The theory provides flexibility in system modeling because it can be used both as a unifying mathematical framework to relate heterogeneous models of computations and as a formal vehicle to implement complex systems by combining heterogeneous components. In particular, we introduce an algebra of tag structures to define heterogeneous parallel composition formally. Morphisms between tag structures are used to define relationships between heterogeneous models at different levels of abstraction. In particular, they can be used to represent design transformations from tightly-synchronized specifications to loosely-synchronized implementations. The theory has an important application in the correct-by-construction deployment of synchronous design on distributed architectures.