Transparent failover for forms

Question

Kindly let me know that if real application clusters are implemented in windows enviorment does it gives transparent failover if we are using forms and report only in our applications .that means that if an end user is accessing a form and that node goes down ,he would not come to know and the control switch to some other node and he will continues with his work

Answer 1

TAF implementation has not much to do with RAC. It's client side feature and it will work equally well with RAC, Data Guard, single instance and cold failover databases assuming the service is back when reconnect is issued.
However, Transparent Application Failover is not transparent at all for transactions. Read only activities are pretty much OK and depending on whether you use SESSION of SELECT based method, and user might not see the impact at all.
However, if user session was in the middle of transaction when failure happened, session will not reconnect until user session issues rollback. This is because instance failure in the middle of transaction causes Oracle to rollback the changes and it needs to make sure that user (application) is aware that previous part of the transaction was rolled back. The way it's done - application needs rollback.
So application DOES need to handle these situations. Imagine a transaction that spans across several forms or user interactions and commit at the end. Let's say user is already at the last step and most of transaction has been applied to the database but no commit yet. Failure happens and Oracle rolls everything back naturally to preserve transactional integrity. User/application must realize that to avoid situation when user presses final "DONE" button sending just simple commit while loosing all the changes. The way to handle it is rollback and either to re-try transaction from the beginning (might be a problem in forms) or inform the user that transaction failed and must be retried.
Reports must be ok assuming it's selects only that's probably safely can be assumed for Oracle Reports.
Form might have an issue unless there is something already implemented to handle this but I can't recall (not that I'm a Forms exert though).