MSIX is a new installer technology for Windows that first appeared in Windows 10 version 1809 and it was later backported to Windows 10 versions 1709 and 1803. It replaces Windows Installer (MSI) and the APPX packaging format previously used for Store apps.
MSIX works with all Win32, WPF, Windows Forms, and Universal Windows Platform (Store) applications. It provides modern features like robust updating, a managed security model with flexible capabilities, containerization, support for the Microsoft Store, enterprise management, and custom distribution models.
For more information on MSIX, see Improve Windows Enterprise Application Deployment Reliability and Security using MSIX and MSIX Core Coming to Windows 7 and 8.1 in December, Plus New Features on the Horizon on Petri.
MSIX App Attach is a complimentary feature for Windows Server Remote Desktop Services (RDS) and Windows Virtual Desktop (WVD) that Microsoft has been working on since at least 2019. Currently in public preview, App Attach performs a function like User Profile Disk (UPD) and FSLogix Profile Containers, except for applications.
Both UPD and FSLogix Profile Containers store user profiles in a single.VHDX file that is mounted automatically when users log on to a remote desktop session. While there are other ways to store user profiles separately from the operating system, like roaming profiles, UPD and Profile Containers solve several problems associated with roaming profiles and folder redirection:
MSIX App Attach borrows the ideas behind UPD and Profile Containers and applies them to applications. Apps are stored in a central location in MSIX format and are then attached to the operating system as users log on to remote desktops.
When an application is attached to Windows, it looks and feels exactly like a locally installed app to the user and the operating system. If in the past RDS admins configured golden images containing sets of apps for users, App Attach splits apps and the OS so that apps can be deployed to users and maintained separately.
Windows Virtual Desktop Applications Groups can be used to deploy apps to users without creating new OS images. And if you are using FSLogix Profile Containers as well, user profiles and apps can be managed completely separately from Windows.
To use the public preview, you need to use a version of Windows 10 Enterprise on build 19041 or later. The MSIX Packaging Tool is also required if you don’t have an app already in MSIX format. Attaching and detaching apps is performed using PowerShell scripts. The scripts can be triggered manually or run automatically as startup, logon, logoff, and shutdown scripts.
There are four phases that are performed when using MSIX App Attach to deploy apps to remote desktops:
The staging phase mounts the required virtual hard disk to Windows. And the registering phase adds the app to Windows, so it appears as an installed application. The deregister and destage phases are for removing MSIX App Attach apps.
For more detailed instructions on using the MSIX App Attach (preview), see Microsoft’s website here.
MSIX App Attach was due to come out of preview along with the spring update release of Windows Virtual Desktop and Windows 10 version 2004. But at the time of writing, there’s no indication of whether it will be ready for production use by the end of May.
For more information on the spring update for Windows Virtual Desktop, check out Windows Virtual Desktop Now Backed by Azure Resource Manager on Petri.
Regardless of whether MSIX App Attach will be out of preview by the time Windows 10 version 2004 launches at the end of May, we can likely expect it to be generally available in 2020. And it comes at a good time. Along with other announcements from Microsoft, like improvements to how Teams audiovisuals are handled in WVD to improve performance, MSIX App Attach will help remote desktop users be more productive and IT departments better manage their virtual desktop infrastructures.