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SUMMARY The size and complexity of software in safety‐critical systems is increasing at a rapid pace. One technology that can be used to mitigate this complexity is component‐based software development. However, in spite of the apparent benefits of a component‐based approach to development, little work has been done in applying these concepts to hard real‐time systems. This paper improves the state of the art by making three contributions: (1) we present a component model for hard real‐time systems and define the semantics of different types of component interactions; (2) we present an implementation of a middleware that supports this component model. This middleware combines an open‐source CORBA Component Model (CCM) implementation (MICO) with ARINC‐653: a state‐of‐the‐art real‐time operating systems (RTOS) standard, (3) finally; we describe a modeling environment that enables design, analysis, and deployment of component assemblies. We conclude with a discussion of the lessons learned during this exercise. Our experiences point toward extending both the CCM as well as revising the ARINC‐653. Copyright © 2011 John Wiley & Sons, Ltd.

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This article describes methods for online model-based diagnosis of subsystems of the advanced life support system (ALS). The diagnosis methodology is tailored to detect, isolate, and identify faults in components of the system quickly so that fault-adaptive control techniques can be applied to maintain system operation without interruption. We describe the components of our hybrid modeling scheme and the diagnosis methodology, and then demonstrate the effectiveness of this methodology by building a detailed model of the reverse osmosis (RO) system of the water recovery system (WRS) of the ALS. This model is validated with real data collected from an experimental testbed at NASA JSC. A number of diagnosis experiments run on simulated faulty data are presented and the results are discussed.