how to fetch data from SQL server to Oracle server?

There are two method we can use to fetch data from SQL server to oracle server

1.install Odbc driver on oracle server and communicate to sql server an fetch the server and this will eat more CPU.
2.This method will be good method and easy also.
but this required gatewy server between oracle and sql server

steps
1.put gateway server entry on oracle tnsnames.ora
2.put another entry on gateway server about oracle server,os that both can talk to each other
3.add entry on listener on gateway server
4.add entry on driver on gateway server
c:\oracle\11g\dg4msql\admin\init<dbname>.ora
5.create user on sql server windows auth
6.create DB link on oracle server using sql server user and start fetch the data