Replicating MMS clients for fault tolerance

Abstract

This paper addresses the problems concerning the faulttolerant distributed replication of a controlling application in an automated system. The Manufacturing Message Specificafion ( M M S ) is used as a communication protocol between the controlling application ( M M S client) and the automated industrial equipment (MMS servers). A distribufed systems toolkif @ST) is used to manage the replication of the controlling application. We identify potential obstacles in the MMS environment when passive client replication is used. We suggest methods that the recovering client can use to overme these obstacles. The solutions and alternatives proposed are discussed with respect to their conformance to tbe MMS standard.