Auto-patching

I am trying to develop a small online game. The problem is each time I roll out a new release my testers all have to do a full re-install.
So, I want to make an auto-patcher. However I dont really know where to start.
Each realease is in its own version directory, so we have a point of reference.

Can anyone please point out to me various methodologies that i may make use of please. (Also will I need to set my server to be a FTP server too or is there anotehr way to stend down the files they may need)

Thanks

heres an idea:

The main game exe is actually just simply an update client which connects to your server (you could use http for this connection) and downloads a reference file. the reference file contains a list of all updated files...
it then downloads and overwrites all the updated files.


if no update is available, the update client starts the main exe... if an update IS available, it updates and then runs the main exe


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a more advanced thing:

if the update exe finds an "update client" update, it runs a third, "updateclient updater.exe" which downloads and updates the new update client. this then runs the updated update client.....






Sorry---- hope that makes sence!

Hey good idea! :)