ENTERPRISE STRATEGIES: Carry your state - Standard techniques for contingency planning don't map well to service-oriented communications.

CONCEPTS SUCH AS BPM (business process management), federated computing, and Web services would not exist were it not for reliable, low-latency networks. Such service-oriented architectures entail calling out to multiple systems. But what happens when a system or network loses its connection, overloads, or hands back garbled data?

Standard contingency planning is coarse-grained: an entire site, server, or application is failed over. After fail over, existing sessions (such as database queries and credit card authorizations that were already underway) are usually dropped.

But the coarse-grained contingency model runs aground in a service- oriented design. One …