Propel is a free, open-source (MIT) object-relational mapping toolkit written in PHP. It is also an integral part of the PHP framework Symfony
Propel’s primary function is to provide a mapping between PHP classes and database tables.
To accomplish this Propel includes a generator component which uses source code generation to build PHP classes based on a datamodel definition written in XML.
Propel also includes a runtime component which manages connections, transactions, and any idiosyncratic rules that describe the workings of the RDBMS being used with Propel.
Propel was originally based on the Apache Torque project, which was a Java language ORM project.