This presentation describes a rule-based system built using the JESS rules engine deployed on a cluster of JBoss application servers. The evaluation process and the decision to use JESS as the foundation of the application is provided. The application is an automated underwriting engine for lending decisions. Addressed are the issues of redundancy, hot deployment of both code and rules and administration and monitoring of statistical and state information on the underwriting engine. Also presented are performance numbers and simple optimization strategies on both cluster and application levels.