RITE is exactly what I want to need.

The problem is that distributed systems (like message queues or notification services) are required to be fast/scalable but very hard to program/debug/test. One solution is embedding plugin mechanism in a carefully programmed framework. There are examples such as Tokyo Tyrant's Lua plugin or Apache Solr's plugin mechanism. But rather than Lua or Java, I want to use Ruby because it's syntax and semantics are very suitable to write plugins.

RITE will make it possible. Ruby may be new standard of embedded languages.