ClickOnce functionality allows you to create an application that checks for updates. It can do this before it starts (you’ll always run with the latest version, even if you will see the update-check when it starts) or after it starts (better for large updates). When you’re publishing, you can also specify the minimum acceptable version that is to be running, which will automatically do the update when in violation. It obviously follows that you can also specify whether the application is allowed to be run when offline (read: when it can’t check for updates).
Though most aspects of Microsoft development are unnecessarily complicated this is ridiculously easy.
Open project properties and go to the “Signing” panel:
Check the “Sign the ClickOnce manifests” checkbox. Click the “Create Test Certificate…” button and create a self-signed certificate (you can create an official one after you adopt and formalize the process):
Navigate to the “Publish” panel and fill in the path to push files and the UNC/URL that that directory can be accessed at for update polling and downloads:
Click on the “Updates…” button and check “The application should check for updates”. Make sure to change where in the lifecycle the update should be performed if the default doesn’t work for you. Check “Specify a minimum required version for this application” and set that version if you want the update to be automatic. When you enable this for the first time, it will likely default to the version that is currently set to publish:
Back in the top “Publish” panel, click on “Publish Now”. You may change the version factors of what you’re publishing, but, as the “Automatically increment revision with each publish” checkbox is checked by default, you shouldn’t have to:
An Explorer window with the published files will probably be opened for you:
Go ahead and click setup.exe to install. Forgive the unsigned-publisher security warning:
You’ll also be presented with a security warning due to the self-signed certificate. Click on “More info” to expose the “Run anyway” button and then click it:
Go ahead and do another publish (it’ll automatically push using a higher version than last time). Run the application. You’ll be prompted to update unless you changed the minimum-version in order to install automatically: