Hey there, I'm developing an app for reading data from a USB attached device on honeycomb (3.2). The device reads data from an external infrared meter prepares data and shares them over mass storage. It means the USB device is mounted as mass storage device. As it updates and creates some files by itself the android file-system doesn't seem to recognize the changes.
The only solution seems to mount/unmount the device over the settings menu. After "remounting" all data is updated as this is the most effective way to force android to refresh the file-system-cache. But this solution is not practical for daily use. So I looked for a solution to mount/unmount USB storage by code and found the "MOUNT_UNMOUNT_FILESYSTEM" permission, google led me to some information about IMountService but I'm unable to find any documentation about IMountService on honeycomb. Every implementation or use of this service seemed to be on Android 2.x and might need root. As I'm using a ASUS Transformer for developing I saw that ASUS provides a widget to unmount mass storage devices which is located next to the clock in the bottom right corner. What leads me to assume that there has to be an Interface to mount/unmount devices. ASUS doesn't support third party developers and doesn't want to give me some information about that issue. I had no success trying to implement the MountService with the documentations I found even on a rooted device. *All this led me to the assumption that IMountService is only available for OS developers (like Asus, Acer and so on) and not for SDK developers. Am I right with this?* Trying to find another way to force honeycomb to refresh the file-system-cache and re-read data from the device a colleague mentioned that creating a new file in the folder I try to read might force honeycomb to synchronize device data and cache data. Try and Error again and again no success I can see the created file appearing in different file explorers and disappearing when deleted but all other files doesn't seem to be updated. Another thing might be that all data produced by the USB device have a time-stamp from 2004 or 2005 so honeycomb might be intelligent enough not to update these files as they have no current timestamp. Trying to use "Runtime.exec()" to run a touch command and update the time-stamp led to errors on unrooted tablet and had no effect with a rooted tablet. Now the question is: *Is there any documentation how to access the MountService or equivalent on honeycomb as an SDK developer?* The developers doesn't seem to provide permissions that can not be used by any API call and the reference<http://developer.android.com/reference/android/Manifest.permission.html#MOUNT_UNMOUNT_FILESYSTEMS>clearly says that this permission is used to mount / unmount file-systems. *Or is there any other way to force honeycomb flushing the file-system-cache and reload all files?* Maybe there's an option in ICS (4.0) as this version is completely open source and honeycombs source code was only provided to the vendors. Thanks for reading this and hopefully giving me a hint ;-) -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
