ABSTRACT

Informally, a system is a “real-time” one if its core properties of timeliness and predictability of timeliness are integral to its logic, not just performance measures. In general, those properties are dynamic due to intrinsic aleatory and epistemic
uncertainties about parameters of the system and its application environment; this book refers to "dynamically real-time." Despite such uncertainties, dynamically real-time systems have mixed application-specific kinds and degrees of criticality—
including even the most extreme safety-critical systems (e.g., for warfare)—which can be expressed in terms of application qualities of services. Traditional real-time computing systems are a narrow special case whose parameters and core properties are
predominately static, and their values and time evolution are presumed to be known á priori. Those systems have very limited (albeit potentially important) applicability. Many dynamically real-time systems exist, created by application domain experts
outside of (and unseen by) the real-time computing field. These experiences have been typically (but not always) held as enterprise proprietary or government classified. They usually suffer from the lack of a coherent foundation for real-time per se. The
design, implementation, and application of real-time systems (both static and dynamic) can be extended and strengthened by creating such a foundation based on first principles for those core properties. This book introduces one approach to that.
Timeliness is dynamically expressive using my time/utility (née time/value) functions and utility accrual (née value-based) scheduling paradigm. In this book, uncertainty of timeliness predictability is reasoned about—beyond what is possible with
conventional probability theory—using application-specific instances of mathematical theories of evidence based on belief functions (Dempster-Shafer theory and its subsequent elaborations). This foundation has been successfully employed in different
real-time contexts having wickedly dynamic parameters and core properties, where traditional static real-time perspectives and traditions were inadequate and counter-productive.

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