How can we use watch folder or timer concept in plugin using SDK? Please anyone answer my question
1. You cannot wait in a plug-in, because it causes Acrobat to wait. You can register an IdleProc, which will be called at intervals.
2. Be very cautious of Acrobat's EULA, which prevents server use of Acrobat. This doesn't just mean "use on a server". It would mean that if the watched folder was doing work dropped in there by other users, or automatic processes, then it's a server and a license violation. Essentially the only use is a folder into which the logged in user manually drops files. Other Adobe solutions may exist which have server licenses. The LiveCycle suite of server products (not LiveCycle Designer) support watched folders.
3. Acrobat must run as a foreground app for the logged in user. It cannot be run as a service or background task.
You can't. Use an Action(Batch Process). The concept of watching a folder will put you in violation of the Acrobat EULA.