On Shouting “Fire!”: Regulating Decoupled Communication in Distributed Systems
Decoupled communication, which requires no direct association between the producers of information and its consumers — as under the publish/subscribe (P/S) middleware — is often essential for the integration of distributed and heterogeneous applications. But the indefinite, and potentially global, reach of decoupled communication — the very reason for its power — has a dark side, which may complicate the system using it, making it less predictable, more brittle, and less safe. Just think about the effect of shouting “fire” in a packed theatre, particularly, but not only, if it is a false alarm. p ]It is our thesis that the inherent drawbacks of decoupled communication can be tamed by decentralized regulation of its use. We show how such regulation can be carried out scalably by means of a distributed control mechanism called Law-Governed Interaction (LGI), and a middleware called Moses that implements this mechanism. Along the way, we illustrate the importance of such regulation, and its effectiveness, by considering the treatment of alarms in a large hospital.
KeywordsHome Agent Facility Manager Primitive Operation Processing Thread Packed Theatre
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