The following news shouldn't be a surprise to anyone who's got their groove on with Ruby on Rails. In a new article on SAP Developer Network, german Ruby on Rails developer Piers Harding describes how to easy it is to integrate Ruby on Rails applications to SAP business-related functions via BAPI.
SAP on Rails focuses on providing an alternative type of Model template to the default - ActiveRecord.
This is done via SAP::Rfc which allows RFC calls to SAP from Ruby, with automatic handling of data types, and discovery of interface definitions for RFCs. Some of this has been covered in a previous article, and on SDN.
The model templating class is SAP4Rails. It's job is to automatically build up connections to R/3, look up the interface definitions for the collection of associated RFCs, and to hold the attribute definitions for the given model. This, coincidentally, corresponds to the SAP Business Objects view of the world in BAPIs.