Installing software on user PCs can be a significant burden, especially in a corporate network environment where there are many PCs which may be spread out geographically. This burden magnifies significantly for new software that is updated frequently with new features and bug-fixes. ClickOnce is a technology from Microsoft specifically aimed at reducing the burden of rolling out client software.

ClickOnce applications are deployed with a ‘lightweight’ installation that avoids both writing files under the Program Files directory and writing registry entries. This makes deployment on locked down PCs much easier. However, note that entries are added to both the Start menu and the Add/Remove Programs applet, so the program does behave as though it was fully installed to some extent.

The client software is put onto a web server somewhere on the corporate LAN. To start the program users browse to a special web page and the ClickOnce system automatically downloads and installs the software onto their computer. Updates can be installed onto the web server and are automatically downloaded to the user PCs the next time the user runs the application.

ClickOnce applications have to be secured with an appropriate code-signing certificate. In effect, this shifts the burden of installation security from the individual client PCs to a ‘one off’ action on the web server, thus greatly simplifying deployment across corporate networks.

For more information on ClickOnce technology visit Microsoft’s website at http://msdn.microsoft.com/en-us/library/ms227409(VS.80).aspx