A rundown on what we know about MSIX AppAttach

AppAttach is based on, or extends existing MSIX technology. It allows you to take any existing MSIX package, without altering or repackaging and ‘stream’ it to a virtual or physical machine, much like you are used to with existing Application Layering products. It is also been mentioned that Microsoft is slowly moving away from existing solutions like App-V, for example, and thus positioning MSIX as their main technology for application packaging/provisioning purposes going forward.

Whole article has been updated as of October the 18th. Big list of facts and helpful links near the bottom.

A few intro bullets first

• The MSIX technology is still relatively new, it got introduced during Microsoft Build last year. And while Microsoft has announced to slowly move away from App-V, many do not see it as a worthy replacement at this point and are worried about what might happen next. Read this (1) and this (2) post (in order) to better understand what is going on.

App-V is not under active development but it is supported in Windows 10. We will work closely with our App-V customers to ensure that their requirements are met by the future of app deployment, MSIX in conjunction with SCCM/InTune – Andrew Clinick, Microsoft

• By the way, here you can find more details around MSIX, what it is, what it does or can do, and how it works.
• During this year’s Build (2019) they (WVD, ex-Fslogix team) showed a sneak preview of MSIX AppAttach, have a look at the YouTube video if you are interested. Start around 38 minutes or so if the other stuff doesn’t interest you.

AppAttach

MSIX AppAttach brings us all the perks that Application Layering and App-V have been doing for years. Mainly by creating an abstraction layer of the application so that it can be more easily managed, updated and such. However, according to Microsoft some of the added advantages over ‘traditional’ App Layering products are:

• You can use existing MSIX packages, no altering or repackaging needed.
• No ‘special’ deployment servers are needed.
• No performance impact.     

Based on what we know today, let’s have a closer look. If you already have and/or are using MSIX packages I would agree, you can re-use them pretty much instantly – when it comes to AppAttach that is, at least in theory. However, MSIX packages don’t just fall from the sky now do they :) Also, AppAttach packages are ‘streamed’ from a file server, pretty much identical to app layering.

Application Layering works in the same way that deployment servers, or something similar are not needed. As far as the performance impact goes, we’ll just have to wait and see/find out.

Having said that, MSIX AppAttach packages can be used on-premises as well as within Azure, or AWS, for example, without any modifications. Also, there are no dependencies to the underlying Operating System, which also helps.

With AppAttach, VHD’s (holding the MSIX packages) are mounted onto the OS, filter drivers do their magic – the Fslogix ones in this case – and the Operating System does not know the difference. Again, the concept of Application Layering is the same.

Of course, we don’t have any specific details yet. It has been mentioned that existing API’s within Windows are leveraged to perform an App-Attach, how this might be different from what we are used to is to be seen. From a management perspective (consoles included) they might be able to provide a better integration and user/management experience. Time will tell, it’s a nice development.

As with WVD (the whole world suddenly has an interest in (Windows) Virtual Desktops, it’s like they’ve never heard of VDI, DaaS, or something similar) the same thing might happen here (it’s going be the future of managing/provisioning apps within WVD, so there’s that). While a great deal of companies are already using, or at least know of App-V, application streaming/layering – or app attach might become overly popular as well. Microsoft certainly has the marketing tools to get the job done.

Facts listed

Here are some (publicly known) facts we’ve come to learn so far:

• AppAttach will officially be named: MSIX app attach (notice the non-capital writing) – according to Randy Cook on Twitter. Go follow him here: @randycoder for the latest and greatest on all this. Thanks, Randy, for sharing.
• AppAttach will leverage existing and new MSIX packages for streaming/mounting purposes.
• Microsoft is looking for volunteers. Go here if you would like to test the preview of MSIX app attach. Fill in your name, email, company and industry, that’s it.
• Existing MSI’s, .EXE’s as well as existing App-V packages can be converted to MSIX packages – see a few bullets below for the MSIX packaging tool and the accompanying insider program.
• MSIX AppAttach packages run in something called a helium container. It’s not a 100% clear if and how this differs from an App-V container, from an isolation point of view, that is.
• Existing API’s within Windows will be used to perform an AppAttach to the Operating System. It will (become) an integral part of the Windows Operating System.
• The concept is the same as with Application Layering. A VHD containing the MSIX package will be attached to the Operating System. The underlying technology stack (filter drivers) takes care of the rest. The “Mounting” process takes place on user login.
• Remember Microsoft’s User Profile Disk (UPD)? The concept is similar.
• An AppAttach SDK is in the making. Third party app layering / provisioning companies/products will be able to leverage this, adding value. This is how MSIX packages can be made part of the VHD.
• MSIX and AppAttach packages can be stored on separate storage platforms. Have a look here. Microsoft recently shared a nice resource listing various storage options for storing your MSIX packages, FSLogix containers, and thus AppAttach VHD’s as well. Go here.
• AppAttach packages can be assigned on a per user, or usergroup basis and will be available at login, as mentioned previously.
• It will use the Fslogix technology stack (filter drivers) to do so and it works with app masking as well.
• By the way, FSLogix falls under the WVD/RDS team, AppAttach is being developed by the MSIX team within Microsoft.
• Once the AppAttach package/VHD is attached, the application will seem local to the Operating System and will act as such.
• It will work for virtual and physical machines, single and multi-user, on-premises and in the Cloud.
• Multiple machines can read from a single AppAttach package at the same time.
• We’re talking about block level read only access for efficiency purposes (there’s that filter driver magic again).
• No exact (storage/file server) “sizing” recommendations are available at this time. Or maybe I missed them, if so, let me know. Existing documentation from FSLogix will probably do just fine.
• The MSIX team is currently working on the AppAttach documentation. The next Windows 10 preview release will have all the bits included so people can start testing.
• There already is a MSIX packaging tool available, go here The latest release can be found here including the release notes.
• Go here if you are interested in the MSIX Packaging Tool Insider Program. You will get early access to IT pros and developers who are interested in converting existing desktop applications into MSIX packages.
• Fellow MVP Freek Berson wrote an great article on MSIX app attach where he also show the MSIX packaging process (screenshots included). Note that it is based on very early, pre-private software/technology meant for sneak peek purposes only.
• Eventually this will become the native/default way of dealing with applications for the Windows Virtual Desktop platform.
• Once they have this in pace, it will be (abstraction) ‘layers’ all the way down. From the user profile/data to applications.
• Here’s a YouTube video from Microsoft’s Build conference. It’s on WVD primarily. Fast forward to around 38 minutes to view the part on MSIX AppAttach.
• AppAttach is NOT meant to be a WVD solution/technology only.  
• Keep an eye on the Microsoft Ignite 2019 congress. There will be multiple sessions on WVD and MSIX app attach exclusively. For example, THR3074 – MSIX app attach the future of app delivery in virtual environments – the only session I cloud find with “app attach” in its title.
• This search will show you all Windows Virtual Desktop (key search word) related sessions at Ignite 2019.
• This search will show you all MSIX (key search word) related sessions at Ignite 2019.

Let’s see how all this unveils going forward. First up is Ignite. I won’t be there personally, but I’ll be following the event online the best I can. For those who will attend, have fun and don’t drink too much!

Bas van Kaam

Field CTO EMEA by day, author by night @ Nerdio

Father of three, EMEA Field CTO @ Nerdio, Author of the book Van de Basis tot aan Meester in de Cloud, Co-author of the book Project Byte-Sized and Yuthor of the book: Inside Citrix – The FlexCast Management Architecture, over 500 blog posts and multiple (ultimate) cheat sheets/e-books. Public speaker, sport enthusiast­­­­­­­­: above-average runner, 3 x burpee-mile finisher and a former semiprofessional snooker player. IT community participant and initiator of the AVD User group Community world wide.