Or maybe just limit themselves to unzip to the same directory as the .dcupdate file?
this is what i was thinking.
I think unzip would be the simplest unless the plugin installer needs to do some pre or post commands before/after the installation like deleting some old stuff etc.
yes, in fact this pretty much cancels the idea of simply shelling an exe unzipper, since the updater may need to do post processing, and thus needs to know when unzipping has finished. i'm looking for an open source unzip lib now..
External EXE is also good, but then you might have different people using different installer...Inno, NSIS, MSI...., so the user-experience might not be consistent. Also, they might all show up as entries in Add/Remove Programs.
the updater already supports launching downloaded exe installers.