A design pattern for using non-developmental items in real-time Java

Abstract

This paper addresses the need to reduce the difficulties in developing time-constrained Java applications. We present a design pattern for a class of time-constrained real-time applications that allows developers to use (and re-use) Java code libraries and non-developmental items (NDI). The proposed design pattern simplifies the implementation of the timeconstrained tasks substantially by not requiring the use of no-heap real-time threads. We tested the design pattern with the Java RealTime System (RTS) 2.0 from the Sun Microsystems. This paper also presents a simple methodology for determining the appropriate values for the RTS run-time parameters (thread priorities, memory usage, process load, and task deadlines) in order to ensure the deterministic execution of the timeconstrained tasks.

A Comparison of Priority-based and Incremental Real-Time Garbage Collectors in the Implementation of the Shadow Design Pattern

“…For easy reference, we will describe briefly in this section our Shadow Design Pattern for real-time applications reported in [9,10], which is defined by the following two key features:…”

“…In [8], we concluded that it is preferable to use only the regular, heap-using real-time threads for a class of real-time applications whose computations must be terminated by their hard deadlines and have to return the best approximations to their clients if they cannot finish their computations by the deadlines; we developed a new design pattern, called the Shadow Design Pattern, for this class of applications. We described how well this design pattern works with the Sun Java Real-Time System (RTS) 2.0 in [9]. The key feature that makes the Shadow Design Pattern successful is the availability of the real-time garbage collector (RTGC) whose priority is assignable.…”