Remote application deployment

Question

We have a c#, .NET 4.0, windows application which we deploy to a terminal server. (Developed using VS 2010). This application makes use of several WCF services sitting on another server.

Our users access the front-end via remote desktop session. (They all have a .RDP file on their desktops.)

My question is regarding the deployment of this front-end. Currently, if we need to do an emergency deployment during business hours, we need to kick all the users off that are hooked into the app (as they are using the dll's that we need to replace). This is not ideal, obviously. We work in quite a business-critical environment, so these deployments are unavoidable. I've investigated ClickOnce, but have read that you cannot use this with terminal services application here. (Which kind of makes sense since it's essentially one app being "accessed" by several clients...)

I would like to be able to do a "silent" deployment whereby the user knows nothing about the fix until they restart their instance of the application. I'm not sure this is even possible?

I would appreciate any guidance or suggestions on this!

Answer 1

Yep, I do this all the time with a RD app -- you just need to move or rename the DLLs instead of deleting them. Windows allows moves and renames when DLLs are in use, but prevents you from deleting them. If you use Windows Installer to deploy your app, it will do the moves automatically (and delete the old versions when the system is next rebooted).

Once you replace the DLLs this way, existing sessions will continue to use the old, renamed versions, and new sessions will use the new versions. Of course, depending on how many DLLs you have, how long it takes your app to load them into memory, and how much activity you have on your server, you could run into a scenario where the app loads some of the old DLLs and some of the new ones when you're in the middle of updating them, but that would likely be rare.