Vapor is a persistent Object-Repository for Ruby, providing transparent persistence of Ruby objects to a PostgreSQL database. It's goal is to provide developers with an easy-to-use persistence framework that does not interfere with the code of classes that are to be persistently stored. Vapor does not require any knowledge about relational databases, so developers can concentrate on the task of writing their application logic. Some of Vapor's general design was inspired by the JDO (Java Data Objects) standard.