Event-Driven Architectures for Distributed Crisis Management

Abstract

This paper describes an approach for developing distributed applications that help deal with rapidly changing situations such as terrorist attacks, hurricanes and supply chain disruptions. Important characteristics of such applications are that they must handle unexpected events and that they are often modified on-the-fly, by multiple people who may belong to different organizations, to deal with changing situations. Abstract and concrete models for specifying, reasoning about, and implementing such systems are presented. In the abstract model, an application is a set of state transition rules over the global state of a distributed system. In the concrete model, an application is a set of messagedriven processes and each computation is a sequence of atomic operations in which a process receives a message, changes its state, and sends messages. An implementation of the concrete model using XML as the message and state format, with state transitions specified using XSLT, is briefly described. A key feature of this implementation is that messages and process states are represented using a format that allows applications to be easily observed and modified during their execution