IMPLEMENTING AND EVALUATING THE PUBLISH/SUBSCRIBE PARADIGM USING THE OMG’S DDS/DAIS SPECIFICATIONS APPLICATION TO IDEC’S MICRO3 PLC COMPUTER LINK SYSTEM

S. Hasnaoui∗

Keywords

Publish/Subscribe/Distribute paradigm, DAIS specification, IDEC’s micro3 PLC, DDS, OLE for process control data exchange specifi cation, performance analysis

Abstract

Distributed computer control in complex embedded systems and their software components gain complexity when these systems are equipped with many microcontrollers which oversee diverse electronic control units connecting hundreds or thousands of analogue and digital sensors and actuators. These systems need new interobject communication patterns. The Publish/Subscribe paradigm matches well with these patterns. This paradigm is extremely attractive for structuring object-oriented Distributed Control Systems (DCS). The Data Acquisition from Industrial Systems (DAIS) specification proposed by the OMG Manufacturing Task Force provides a middleware for DCS with a data acquisition specification. The main objective of this paper is to demonstrate how DAIS specification is projected in a Publish/Subscribe point of view and gives a concrete example in a real world application using IDEC’s micro3 PLC in a computer link system [1]. This paper also gives some performance analysis and comparisons to other competitive Publish/Subscribe models like the OMG’s Data Distribution Service (DDS) and OLE for Process Control Data eXchange specification (OPC-DX), widely adopted in distributed and real-time intelligent control systems.

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