1. We have two oracle 10g database , one on Linux and other on windows.
2. At a given point of time any one of these database will be updated and same must be sychronised with the second database.
3.Primary need for such an arrangement is that if one database goes down the other should be always available with the latest update and once the database that was down comes up , again both should be synchronised.
=> Phsyical DataGuard supports different platforms, but not different versions. So no option.
=> Logical Standby => while supporting different versions of database, it hat platform restrictions. So especially with 10g is not an option as well
=> GoldenGate is probably the way to go, but unfortunately not a cost free option. But would ideally support what you expect.
=> Streams might be possible as well...