New Schedulability Analysis for Real-Time Systems based on MDE and Petri Nets Model at Early Design Stages Mohamed Naija 1 , Samir Ben Ahmed 1 and Jean-Michel Bruel² 1 Laboratory of Computer for Industrial Systems, INSAT, Tunis, Tunisia ²Institute of Computer Science Research, IRIT, Toulouse, France Keywords: Real-Time Embedded Systems, Concurrency Model, MARTE, Schedulability Analysis, Petri Nets, Design. Abstract: Transforming a software functional model that describes the underlying application to a concurrency model is considered as a critical issue in the model-based approaches for Real-Time Embedded Systems (RTES) development process. The formal methods have proven to be useful for making the development process reliable at a high abstraction level. Based on this approach, this current research proposes a generic approach to task construction that allows early detection of unfeasible design. Having a component-oriented specification as entry, the first stage of the methodology consists in the workload model specification. The workload model represents the system end-to-end computations triggered by an external stimulus and subject to hard real-time constraints. This model is then mapped into a Petri Nets formalism to perform P- invariant method and generate all transactions in an optimized way. The refinement of the transaction set in a Schedulability Analysis Model defining an optimized threading strategy model. The latter presents the set of units of execution taken into account by the scheduler of the system and their scheduling parameters. We illustrate the advantages and effectiveness of the proposed method by constructing a concurrency model for a combined Cruise Control System and Anti-lock Braking System. 1 INTRODUCTION In the development of Real-Time Embedded Systems (RTES), component-oriented high-level specifications are used to manage complexity. Each software component encapsulates the implementation of a specific functionality which is accessible only through the input and output access points. In that context, the software application is described in a component-based model (called also functional model) still being independent of any specific platforms. Hence, this functional model (Mraidha et al, 2011) constitutes a first step in the definition of a structure able to fulfil requirements for the system. After building a logical component model, it is necessary to synthesize a mapping of functional blocks on threads in order to support the verification of non-functional requirements (NFP) at early design stages. The choice of the threading strategy defines how the system reacts due to an external event or a timer. Finding the adequate number of threads and the good grouping of functions to threads relies mainly on the designer experience towards the definition of a concurrency model of the system. Thus, the real-time application is described in a concurrency model that runs on a given target hardware platform and satisfies timing constraints. To this end an abstracted run-time model of the platform has to be assumed. In fact, the scheduling analysis phase makes it possible to predict and validate the concurrency model before the design stage. An analysis carried out earlier makes it possible to guide the designer in the construction of a valid design model with respect to the threading strategy. In this paper, we incorporate mapping functional blocks on threads problem in the design optimization. Since threading strategy is NP-hard problem, it is recommended to apply formal techniques intended to reduce the problem impact. This allows the construction and the validation of the concurrency model that is reliable at early design stage. The proposed approach adopts the model- driven engineering. Indeed, the system behavior that is in response to external stimuli and platform resources are annotated with MARTE (OMG, 2008) 330 Naija M., Ben Ahmed S. and Bruel J.. New Schedulability Analysis for Real-Time Systems based on MDE and Petri Nets Model at Early Design Stages. DOI: 10.5220/0005514003300338 In Proceedings of the 10th International Conference on Software Engineering and Applications (ICSOFT-EA-2015), pages 330-338 ISBN: 978-989-758-114-4 Copyright c  2015 SCITEPRESS (Science and Technology Publications, Lda.)