Experiences Using Adaptive Middleware in Distributed Real-time Embedded Application Contexts: a Dependability Perspective
Citation: Gill CD, Loyall JP, Schantz RE, Schmidt DC. Experiences Using Adaptive Middleware in Distributed Real-time Embedded Application Contexts: a Dependability Perspective. Workshop on Dependable Middleware-Based Systems, Part of Dependable Systems and Networks Conference (DSN 2002), June 26, 2002, Bethesda, Maryland.
Abstract Over the past few years we have developed a number of real world applications that have both motivated and used middleware technologies for COTS-based distributed object computing in general, and runtime adaptive behavior in particular. In this context, a new twist on the theme of dependability involves adaptation as an effective means for dealing with the less-than-optimum situations that often arise due to failures and other forms of sudden, unexpected behavior. This paper briefly describes two of these applications, Weapons Systems Open Architecture (WSOA) and Unmanned Aerial Vehicles (UAV), which have already undergone a series of evaluation steps to determine the suitability of their concepts and implementations under realistic usage scenarios. Our focus in this paper is on the adaptivity exhibited by WSOA and UAV applications under changing operating conditions, and on the technical basis for the effective marshaling of modified workplans to keep application mission objectives focused using available resources. We summarize some of the lessons learned thus far in developing these applications and the underlying middleware technologies, and show how they influence each other. We also assess the suitability of the solutions offered, discuss some of the difficulties encountered along the way, and outline the means we are applying to overcome them. We conclude with some of the key research challenges that must be resolved to field distributed real-time and embedded systems that can be depended upon to perform adequately, even under extreme and unusual operating circumstances.