August was a big month for XenApp and XenDesktop, as Citrix announced our second Long Term Service Release, XenApp and XenDesktop 7.15 LTSR. The 7.15 LTSR is a major milestone for XenApp and XenDesktop on-premises deployments and we think you feel the same way as we have watched the thousands of 7.15 LTSR product downloads in just over two months.

While the Servicing Options program that includes the XenApp and XenDesktop release strategy known as Current Releases (CRs) and Long Term Service Releases (LTSRs) has been around for a few years, there was one key new announcement that warrants this blog post. With 7.15 LTSR, we announced that you can now mix LTSR Virtual Delivery Agents (VDAs) in Current Release and Citrix Cloud deployments. A picture is worth a thousand words, so let’s start with the picture first:

  • Citrix Cloud XenApp and XenDesktop Service: If you are currently leveraging the XenApp and XenDesktop Service from Citrix Cloud, then you can now utilize the speed and agility of the cloud-hosted management in conjunction with on-premises instances of the LTSR VDA (blue) and/or CR VDAs (orange). This could prove to be very beneficial in a scenario where you have a sensitive application that might need rigorous security/compliance testing with any upgrade. For this sensitive app you could leverage the LTSR VDA; however, in parallel you might want to introduce a new Windows Server 2016 application. Leveraging the XenApp and XenDesktop Service now gives you the best of both worlds; you have the agility of a cloud service paired with the predictability of the LTSR VDA for your highly regulated application and the latest innovation for Server 2016 application with your CR VDA.
  • Current Release: Here the same logic holds true, you can run the latest Current Release management components (Controller, StoreFront, Director, etc.) to keep your environment on the latest technology; however, you might have one application that needs to continue to run on a legacy OS such as Server 2008R2 or Windows 7. A great example here might even be migrating from an older XenApp 6.5 farm. Here you can use the LTSR VDA for your 2008 R2/XenApp 6.5 applications, but all your modern applications as well as the management plane are leveraging the innovation and functionality of the latest Current Release.
  • Long Term Service Release: Many customers love the long-term predictability and maintenance schedule associated with the LTSR (5 years mainstream support plus an optional 5 years of extended maintenance). Again, if you are required to maintain any type of security certification, such as FIPS compliance or Common Criteria certification, it is likely that 7.15 LTSR will appeal to you, especially if you are running on an older version, such as 7.13. In this case, Citrix recommends upgrading the controllers first, so you can transition your management plane to 7.15 LTSR with your 7.13 VDAs and then upgrade your VDAs from here, but remember: to be eligible for the full benefits of LTSR, you can only have LTSR-eligible components running in your environment, as documented here.

All three options extend the power of the 7.15 LTSR to new deployment options, making it even easier to align business goals and technology goals. In addition, Citrix introduces this LTSR VDA deployment flexibility because at the same time Citrix also announced that future Current Releases, starting with any release in Q4 2017, would be deprecating support for legacy operating systems. The 7.15 LTSR product documentation outlined this upcoming change and Citrix product documentation continues to be the single point of reference for this type of information. However, I wanted to work with my colleagues to ensure that all of you were aware of these upcoming changes and also understood why Citrix was moving in this direction. Let’s start with a table summarizing what is changing, again refer to product documentation for complete details:

Let’s walk through some examples:

  • It is likely that Citrix will ship a new version of XenApp and XenDesktop before the end of 2017. That new version of XenApp and XenDesktop VDA will no longer install on Windows Server 2008 R2 or Windows 7. To be specific, the VDA install will check the OS and notify you that 2008R2 or Windows 7 is no longer supported for that Current Release VDA. However, you can still leverage the 7.15 LTSR VDA if you need a 2008 R2 application or Windows 7 desktop within your CR site. You still have options!
  • Changing direction to Windows 10. While Windows 10 is a newer OS, Microsoft has already announced that certain builds of Windows 10 that have reached End of Service. Citrix support for Windows 10 builds aligns with Microsoft, so in future Current Releases of XenApp and XenDesktop Citrix will no longer support those older builds of Windows 10. Our very own Fernando Klurfan does a wonderful job of explaining the Citrix strategy for Windows 10 and you can also reference our master source of XenDesktop and Windows 10 support guidance. Again, Citrix customers can continue to leverage the 7.15 LTSR for Windows 10 Long Term Servicing Channel.

Now, the bigger question is probably ‘Why?’ Why is Citrix dropping support for these legacy OSs in future Current Releases? For starters, Microsoft ended mainstream support for Windows 7 and Windows Server 2008 R2 back in January 2015. More importantly, Microsoft no longer develops or introduce new features on these legacy OSs and Citrix is following the same approach by discontinuing development efforts on these legacy OSs and offering extended support through the 7.15 LTSR VDA.

Additionally, this decision has a lot to do with the evolution of the Windows display and graphics subsystem. Direct2D replaced GDI, Windows 8 introduced the Display Only Driver as part of WDDM 1.2, and Windows 10 v1607 introduced the new Indirect Display Driver (IDD), just to name some examples without turning this into a graphics blog. As a result, the Citrix HDX Graphics stack also evolved taking advantage of these new Windows capabilities, some of which do not exist in the legacy OSs.

In the words of Roberto Moreno, our HDX Graphics PM “With evolution, comes progress, but that also means we must leave some things behind if we want to get ahead. Maintaining legacy code in our current releases limits our ability to innovate, reduces our development agility, and comes at a high cost from a support and engineering perspective. By focusing Citrix engineering efforts on the modern Windows OSs, we can continue to make the industry’s best remote access experience even better, while continuing to support the legacy OSs with our LTSR program.”

By introducing mixed mode sites for Long Term Service Releases (LTSR), Current Releases (CR) and Citrix Cloud, Citrix is giving you the tools to virtualize your mission-critical business applications while delivering innovative new user experiences to help keep your users productive and your business’s technology high performing–giving your organization the competitive edge.