NSF Manufacturing automation applications, such as machine tool controllers, have become more sophisticated in recent years by capitalizing on the technological progress made in the field of computer. However, problems still remain in terms of life-cycle costand lack of openness in commercially available products. There is a general consensus that these applications should have a modular architecture and well-defined interfaces that allow third parties to develop and use these modules independently.
Modules can be either hardware or software.
They typically are subject to a range of timing constraints, which require the DBMS to provide timing guarantees, sometimes under complex conditions. We define a real-time object model that explicitly captures important characteristics of RTDB applications, especially in the manufacturing application domain, namely, timing constraints and performance polymorphism. It uses specialization dimensions to model timing specifications and letter class hierarchies to capture performance polymorphism. The timing constraint of a task refers to the deadline by which the task must be completed. If a system can only make hard deadline guarantees, some application requirements may not be met and the computational resources will be under-utilized.