RUE is intended to be used as a general, local or remote, monitoring tool for any Java based server such as Tomcat, Tyrex, Enhydra, JBoss, JOnAS, etc. RUE is written in 100% Java, and features pluggable samplers and sensors, data visualization plug-ins, configurable data history, output of HTML reports, a standard AWT GUI, JNDI-based sensor lookups, and a simple API for pooling, aggregation, and averaging.