One of the options that was available to you with installations prior to Windows Installer emergence was the ability to rerun an installation multiple times. By this I mean running the setup again without entering Maintenance Mode – as if it had never been run before.
You can still use InstallShield to create an InstallScript using the option and then select the Multi-Instance option which lets your end users rerun an installation multiple times as a first-time installation rather than as a maintenance installation.
But as you know, I studiously avoid InstallScript projects – I use Basic MSI Projects, so how do you make a Basic MSI Project eligible to be rerun?
Note that there are four Standard MSI actions that are the primary method by which the MSI Application is registered under the Windows Installer that we need to be concerned with:
- RegisterUser
- RegisterProduct
- PublishFeatures
- PublishProduct
Alter the condition on each of these Standard Actions to use zero – which means the condition will never be set true and the Standard Action will never run. I recommend you alter the comment to reflect the change – as I have shown above.
Impact
The usage of this technique means the product will not be registered under Windows Installer – nor will it appear in the Add/Remove Programs Control Panel. Use only if you have a specific requirement!
Usage Scenarios
I have encountered two separate situation where this technique served admirably.
Once a vendor was creating unique sales video/slideshow presentations to sell to his customers. After a few customers used his services, he encountered a situation where the same end-client was attempting to install the presentations from two of his customers. The dreaded Maintenance mode was disrupting the end-client from installing the second presentation. I was able to make the install rerunable – and used a scripted Custom Action to read a special file delivered with each presentation. This information allowed me to install the unique files, create shortcuts to access the presentation and create a uninstall technique to allow the end-user to remove the files when no longer required.
Another vendor needed to be able to allow an unlimited amount of customers to be established on the server. Each customer would have a unique IIS Virtual Directory with the same files installed. XML documents that were specially configured during the install would maintain the customer data within the Virtual Directory. A very complex Visual Studio .NET solution was involved to support the customer processes. Each customer install used a rerunable Basic MSI Webproject to deliver the files and create the Virtual Directory.
Warning!
I don't recommend you do this to simply to avoid the Maintenance Mode! A great technique if you have a specific requirement – but you will lose so much functionality that Windows Installer/MSI packages offer.