The readData method adds rows to the caller. It can be implemented in a wide variety of ways and can even populate the caller with rows from a nonrelational data source. In general, a reader may invoke any of the rowset's methods, with one exception. Calling the method execute will cause an SQLException to be thrown because execute may not be called recursively. Also, when a reader invokes RowSet methods, no listeners are notified; that is, no RowSetEvent objects are generated and no RowSetListener methods are invoked. This is true because listeners are already being notified by the method execute.