Scheduling and prototyping of distributed real-time systems (an approach using JINI/JAVASPACES)

Abstract

Scheduling is one of the basic issues in building real-time applications on a distributed computing system. A distributed computing system is typically modeled as a collection of processes interconnected by a communication network. For real-time applications, scheduling is needed to meet applications timing constraints. The major difference between single processor and distributed processors scheduling is that, in addition to deciding which order to execute tasks, distributed processors' scheduling algorithms must also decide which processors the task should run on. Moreover, these algorithms must also take into consideration practical network issues like transmission delay, loss of messages, and synchronization in the absence of a global clock. This thesis proposes a formal model to capture these network constraints and develops a proxy-based network buffer technique to support the inter-process communication for the user-defined distributed real-time systems prototypes generated by the Distributed Computer Aided Prototyping System (DCAPS). The proxy-based technique builds on the Jini/JavaSpaces infrastructure. We have conducted several experiments to measure the response time of inter-process communication via JavaSpaces. We have demonstrated the effectiveness of the proxy-based technique by creating an executable prototype of a user-defined distributed real-time system specification.