Homogeneous connectiity among Oracle databases

Given the Limitations:
· Oracle Database data in geographical region X cannot be physically moved to region Y due to legal constraints
· Oracle Database data in region X can only be accessed remotely from region Y

Given that the volume of data accessed across region with be medium i.e., the OLTP application Z at region Y will access Oracle data from region X remotely. There will be no OLTP application Z at region X where Oracle database data is located.

Questions:
1. What is the recommended (best practice) method of accessing region X Oracle data remotely from region Y using OLTP application Z?
2. What other options are available to remotely access region X Oracle data from region Y?
3. What are the pros & cons of using Oracle DB links to access region X Oracle data from region Y?
4. Is Oracle Gateway required for access of region X Oracle data from region Y – given that end-to-end it is only Oracle database data?

Thanks in advance for your valuable inputs.

Have you looked at doing a logical standby in region Y? Have you thought about doing a physical standby in region Y that you open read only during the day and open as a standby at night so that it can apply redo. Using data guard will make that easier. Have you thought about writing stored procedures to return just the data that you want and pulling that across a db_link? You have a lot of options on how you set this up, it depends on how fresh the data needs to be, how much work are you willing to do to maintain the setup, and whether or not you need to update the data in the source database.