Your JDBC driver should at least implement the methods listed here:

class java.sql.Connection:

Statement createStatement();
void close();
void commit();
void setAutoCommit(boolean autoCommit);

class java.sql.Statement:

boolean  execute(String sql);
ResultSet  getResultSet();

class java.sql.ResultSet:

ResultSetMetaData  getMetaData();
void  beforeFirst();
Object getObject(int columnIndex);
boolean  next();

class java.sql.ResultSetMetaData:

int  getColumnCount();
int  getColumnType(int columnIndex);