I'd use the well documented JSF approach to upload files instead of JSP.
See the HtmlDialogDemos project in your Designer/applications/samples/ directory.
Within there is a demo how to upload a file with an Hmtl User Dialg (JSF): see /FileUploadSimpleModeDemo.ivp/FileUploadSimpleModeDemo.ivp
If you are trying to start a dedicated new case if a file was pushed to the server, you can either start a new case with a trigger activity or use the file pickup start event bean.![alt text][1]
[1]: http://answers.axonivy.com/upfiles/filePickupStartEvent.png