or how can i auto update an app that is not installed via android marketplace. it is useful in scenario where many of our customer uses custom built of android device ( which not yet registered to android ) , and we want to make sure that changes to our app propogate to device ?
This sounds like it might be better asked on stackoverflow.
The autoupdate is a feature of the market. If users haven't installed the app with the market you'll have to implement your own update feature. In Android 2.2 you could potentially take advantage of the push notification system for updates.
You would have to create your own process of having the application notifying the user of updates (and providing a link to the new apk. You could do this with a background service that pops up a message in the notification bar). The user has to install the application from the market to receive updates via the Android market.
To notify an Android phone that an application have a new version (without programming all the process) you have 2 options:
1.- Use the market feature, but for your comments I think this one is out of your list.
2.- Use the notification system available on Android 2.2 and 2.3.
To use this push notification service the device needs to be logged on a Google account in order to receive the notification, so maybe this isn’t suitable for your process.
If no one of this options is what you’re looking for, you will be forced to develop your own push notification system and install that system in every Android phone you need update.