Middleware 2003

### ACM/IFIP/USENIX International Middleware Conference

Rio Othon Palace Hotel

Rio de Janeiro, Brazil

16-20 June 2003

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Website Mirror at the University of São Paulo

## On Shouting Fire!'': Regulating Decoupled Communication in Distributed Systems

Takahiro Murata and Naftaly Minsky (Rutgers U.)

Decoupled communication, which requires no direct association between the producers of information
and its consumers---as under the \emph{publish/subscribe} (P/S) middleware---is often useful 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.
It is our thesis that the inherent drawbacks of decoupled communication can be alleviated 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. And we illustrate the importance of such regulation,
and its effectiveness, by considering the treatment of alarms in a large hospital.
 Latest update: 13 June 2003 - Questions and Comments about the Site: fmc@inf.ufg.br