Abstract To be an effective platform for performance‐sensitive real‐time systems, commodity‐off‐the‐shelf (COTS) distributed object computing (DOC) middleware must support application quality of service (QoS) requirements end‐to‐end. However, conventional COTS DOC middleware does not provide this support, which makes it unsuited for applications with stringent latency, determinism, and priority preservation requirements. It is essential, therefore, to develop standards‐based, COTS DOC middleware that permits the specification, allocation, and enforcement of application QoS requirements end‐to‐end. The real‐time CORBA and messaging specifications in the CORBA 2.4 standard are important steps towards defining standards‐based, COTS DOC middleware that can deliver end‐to‐end QoS support at multiple levels in distributed and embedded real‐time systems. These specifications still lack sufficient detail, however, to portably configure and control processor, communication, and memory resources for applications with stringent QoS requirements. This paper provides four contributions to research on real‐time DOC middleware. First, we illustrate how the CORBA 2.4 real‐time and messaging specifications provide a starting point to address the needs of an important class of applications with stringent real‐time requirements. Second, we illustrate how the CORBA 2.4 specifications are not sufficient to solve all the issues within this application domain. Third, we describe how we have implemented portions of these specifications, as well as several enhancements, using TAO, which is our open‐source real‐time CORBA ORB. Finally, we evaluate the performance of TAO empirically to illustrate how its features address the QoS requirements for certain classes of real‐time applications. Copyright © 2001 John Wiley & Sons, Ltd.

The CORBA Event Service provides a flexible model for asynchronous communication among objects. However, the standard CORBA Event Service specification lacks important features required by real-time applications. For instance, operational flight programs for fighter aircraft have complex real-time processing requirements. This paper describes the design and performance of an object-oriented, real-time implementation of the GORBA Event Service that is designed to meet these requirements.This paper makes three contributions to the design and performance measurement of object-oriented real-time systems. First, it illustrates how to extend the CORBA Event Service so that it is suitable for real-time systems. These extensions support periodic rate-based event processing and efficient event filtering and correlation. Second, it describes how to develop object-oriented event dispatching and scheduling mechanisms that can provide real-time guarantees. Finally, the paper presents benchmarks that demonstrate the performance tradeoffs of alternative concurrent dispatching mechanisms for real-time Event Services.

Cats (Concurrency Analysis Tool Suite) is designed to satisfy several criteria: it must analyze implementation-level Ada source code and check user-specified conditions associated with program source code; it must be modularized in a fashion that supports flexible composition with other tool components, including integration with a variety of testing and analysis techniques; and its performance and capacity must be sufficient for analysis of real application programs. Meeting these objectives together is significantly more difficult than meeting any of them alone. We describe the design and rationale of Cats and report experience with an implementation. The issues addressed here are primarily practical concerns for modularizing and integrating tools for analysis of actual source programs. We also report successful application of Cats to major subsystems of a (nontoy) highly concurrent user interface system.

An approach to statically analyzing a concurrent program not suited for analysis is described. The program is reengineered to reduce the complexity of concurrency-related activities, thereby reducing the size of the concurrency state space. The key to the reengineering process is a metric set that characterizes program task interaction complexity and provides guidance for restructuring. An initial version of a metric set is proposed and applied to two examples to demonstrate the utility of the reengineering-for-analysis process. The reengineering has potential benefits apart from supporting analyzability, following the dictum that if it is hard to analyze, it is hard to understand and maintain.

The commenters discuss several flaws they found in the above-titled paper by G.M. Koran and R.J.A. Burh (see ibid., vol.17, no.10, p.109-1125, (1991)). The commenters argue that the characterization of operational and axiomatic proof method is modified and inaccurate; the classification of modeling techniques for concurrent systems confuses the distinction between state-based and event-based models with the essential distinction between explicit enumeration of behaviors and symbolic manipulation of properties; the statements about the limitations of linear-time temporal logic in relation to nondeterminism are inaccurate; and the characterization of the computational complexity of the analysis technique is overly optimistic.>

Although structural testing techniques are among the weakest available with regard to developing confidence in sequential programs, they are not without merit. The authors extend the notion of structural testing criteria to concurrent programs and propose a hierarchy of supporting structural testing techniques. Coverage criteria described include concurrency state coverage, state transition coverage and synchronization coverage. Requisite support tools include a static concurrency analyzer and either a program transformation system or a powerful run-time monitor. Also helpful is a controllable run-time scheduler. The techniques proposed are suitable for Ada or CSP-like languages. Best results are obtained for programs having only static naming of tasking objects.>