Outlook add-in ClickOnce update settings

Question

I'm trying to deploy Outlook add-in with ClickOnce. While setting the update options I noticed that there are fewer options available for Outlook add in project than there are for Win Forms project. For example I cannot specify minimum required version. Why is that? Also, I would like:

1. to enable manual update
2. to ask user if he even wants an update (if it is not required).

1) I tried using System.Deployment.Application and CheckForDetailedUpdate() function but even though update succeeds there are problems installing it: If i restart my plugin it disappears from Outlook, if I don't the old version gets stuck in Outlook (and behaves oddly) although further updates via UNC path suggest that update has been successfully done.

2) Regular publish with no special options added with Mage or MageUI works in itself, but add-in seems to update without asking a user. Googling a bit reveils that people are trying to do the opposite, so I'm kind of puzzled as to why doesn't it prompt for update by default.

I tried editing manifests generated from Visual Studio with MageUI but it generates invalid XML for application manifest (?! - it misses "assemblyIdentity" node in "dependentAssembly" node), and when i add missing nodes from original manifest generated by VS (and update and sign it afterwards), installation complains about assembly hashes being invalid.

How can I deploy Outlook add-in with said requirements?

Answer 1

VSTO applications (Office Add-Ins) only support certain bits of ClickOnce. You can try adding code and doing programmatic updates, but the ClickOnce lead at Microsoft said it is not really intended to be used, and parts of it might not work. (No, no details on exactly which parts -- you have to do a bit of trial & error).

Also note that the way a vsto deployment works and runs is this: Outlook checks out the vsto app, and copies the dll(s) to a shadow location and loads that with Outlook. When you update the vsto app, it updates it in the click once cache, but not in outlook. When you close outlook and re-open it, it finds the new version, copies it out to the shadow location, and loads it. You can't restart the vsto bit itself and have it do anything. The user must restart Outlook.

This is one of the reasons that updates are performed when starting up the Office application. It looks for the new version, updates if necessary, and then loads it into Outlook and uses it.

Having said that, another way to accomplish what you want is to write a windows forms app that will update your add-in. Basically deploy a winforms app that just shows nothing the first time except invoke the vsto application via clickonce (process.start is your friend). Then you could have the outlook add-in invoke the winforms app the see if there's an update, and if there is, it could prompt for an update of the win forms app, and then uninstall and reinstall the office add-in or update it.