Project Avalon… Excalibur! Part one

Again, lots of new and exciting stuff going on with Citrix! Since I’m still in the researching phase and building up my demo environment I will try and split this Blog into two parts, part one being mostly textual giving you an idea on what it’s about, explain some new and improved technologies being used and getting you into an XenDesktop state of mind (you’ll understand in a minute, keep reading) before moving on to the actual installation and configuration phase being part two, which will be more of an product review. I must say, it looks impressive so far :-)

About nine months ago Mark Templeton announced Project Avalon, Citrix’s next step in delivering applications, data and desktops as a cloud service. It currently consists of two releases with Excalibur being the first and Merlin the second. Three months ago Citrix released the Excalibur Tech Preview available for download, Merlin will shortly follow. The fun continues!

A step forward

Excalibur replaces XenApp and XenDesktop as stand-alone products merging them into a single product and console introducing some new and improved technologies making it easier to set up and manage Sites (used to be called Farms), publish applications, desktops and more. The capabilities previously available within XenApp are now delivered through the XenDesktop infrastructure and components.

Merlin lets you create (self-service and service orchestration capabilities included) public, private and hybrid cloud solutions leveraging technologies like Citrix CloudPortal, the XenApp Cloud Provider Pack and CloudPlatform powered by Apache CloudStack which adds support for provisioning of VDI and hosted shared desktop workloads onto Amazon Web Services, Azure and others. But only if you are an ISP or CSP (Internet or Citrix Service Provider) because of special licensing restrictions that apply to Microsoft products, that goes for all public cloud solutions by the way. CloudPlatform also adds flexibility to XenApp and XenDesktop letting us use different Windows server and client versions and different versions of XenApp and XenDesktop as well.

Components and technologies

Excalibur consists of the following:

  • Citrix Receiver
  • Storefront 2.0
  • Studio
  • Delivery Controller
  • Delivery Agents
  • SQL Database, can be Express
  • Server OS machines
  • Desktop OS machines
  • Flexcast 2.0 / Flexcast Management Architecture (FMA)
  • Intelligent Configuration Validation
  • Profile Management
  • Provisioning / Machine Creation Services (MCS)
  • Server 2012 and Windows 8 compatible
  • Citrix Director
  • HDX Edgesite and other HDX improvements

Merlin makes use of the following technologies:

  • Citrix CloudPortal
  • Citrix XenApp Cloud Provider pack
  • CloudPlatform, powered by Apache CloudStack

The main focus, for now, will be on Excalibur since Merlin (Tech Preview) will be released shortly.

What’s new?

Before we have a closer look at some of the individual components and technologies mentioned above, let’s first address some of the key differences and concepts between XenApp as we know it today and Excalibur, the way it will be. As said, Excalibur merges both XenApp and XenDesktop into a single product in which XenApp, for the most part, will leverage the XenDesktop infrastructure (FMA). Although some of the biggest changes take place at the XenApp side, XenDesktop has a few as well.

Terms and concepts

This is where that XenDesktop state of mind comes in.

A Machine catalog is a collection of virtual and or physical machines managed as a single entity that share a common master image. These machines are then used to run hosted shared applications and desktops (XenApp) or dedicated / pooled virtual desktops (XenDesktop).

A Delivery group (formerly know as a Desktop Group) is a flexible way of allocating machines to users who require access to a common set of applications or desktop resources (catalogs) and require the same end user experience (policies, profiles, personal storage) across those resources. A delivery group can combine multiple different catalogs, with the emphasis on different. Also, a single delivery group can be assigned to users so that a single user may access multiple applications or desktops from that group, more details in a bit.

So what about it?

As far as XenDesktop goes a Catalog is still a catalog, you can have a Windows 7 catalog, a Windows 8 catalog etc… For XenApp however, things are different. From a XenApp point of view you can compare a Catalog with a Worker group with a few exceptions… As you probably know, in a XenApp Farm all the server systems need to have the same operating system installed, no exceptions. So if you have 2 or more Worker groups then all the systems within those groups will have the same OS installed. In Excalibur things work different, for example, you can create two different Catalogs (Worker groups) for use with XenApp in which you can have one Catalog with Windows Server 2008R2 installed and another with Windows Server 2012 and publish two separate hosted shared desktops, all within the same infrastructure, a big change!

This is made possible by Delivery Agents (the old VDA’s in XenDesktop), more on this in a minute. These Agents together with the Delivery Controller are an important part of the improved FlexCast 2.0 technology which I’ll also address later on.

Delivery groups are not a new concept just a name change, used to be called Desktop groups in XenDesktop, they are still created from, or applied to, Catalogs and pretty much fulfill the same tasks. There is a big change though… In earlier versions of XenDesktop you assigned a Desktop Group to a Catalog or multiple Catalogs if needed, but the Catalogs all needed to be exactly the same, meaning that they all shared the same common image, 2008R2 for example. Now, in Excalibur it is possible to assign a single Delivery group to multiple different Catalogs. Think back to the example above, two Catalogs with two different operating systems installed same here but with just one Delivery group assigned to them. Simplified management! The same goes for XenApp, two different Catalogs: 2008R2 and 2012 (which already is a big new feature on its self), one Delivery group.

Off-course this isn’t a requirement, it’s an option. You can still create and configure separate Delivery groups per Catalog if you wish and assign one or multiple desktops to one or multiple users, same rules apply. I borrowed this picture from one of the Citrix Blogs.

Excalibur Catalogs

XenApp vs Exaclibur

XenApp within Excalibur brings some real changes, I’ll list them below:

  • Citrix Studio for all configuration and management tasks.
  • It now uses Microsoft SQL Server for the data store, no more IMA.
  • No more IMA service or protocol, this has been replaced by the FMA.
  • For high availability configure SQL clustering or mirroring or use your hypervisors high availability features by deploying the database as a virtual machine.
  • This also means that Microsoft Access and Oracle are no longer supported.
  • No more Terminal Services required on the Delivery Controller (Data collector).
  • No Data Collectors, load is now evenly distributed across all Controllers in the Site.
  • A Farm is no longer called a Farm, they’re now called Sites.
  • Servers communicate through Delivery Agents, no more XenApp installations needed.
  • Delivery Agents don’t to run on the same OS or version as the Delivery Controller.
  • The Shadow Taskbar is gone, you now use Director which also supports Shadowing.
  • Management can be delegated through build-in Administrator roles or create custom Administrators with roles based on role and scope pairs.

Components and technologies overview

Below I’ll elaborate a bit more on the components and technologies mentioned earlier.

I assume everybody knows what the Receiver is and does, if not, then you will probably have some more questions when you’re done reading :-) No real changes here.

StoreFront can be installed as part of the Excalibur set-up process and is fully managed and configured through Studio. In my previous Blog  about the CloudGateway I already outlined some of the new and improved features like: self-service (app request) capabilities, interaction with Appcontroller if applicable, centralized enterprise app stores (now provisioned from Citrix Studio), Receiver for Web, SmartAccess through the use of Access Gateway, automatic synchronization of user subscriptions and logon information (SSO) and more… There is no more external SQL database, user subscriptions are now stored locally and replicated throughout the StoreFront server group. Another one I’ve missed: StoreFront lets you automatically provision a core set of applications to specific users based on AD group membership just by adding the keyword ‘Auto’ to any resource.

Studio… Just one console to configure and manage both XenApp and XenDesktop. It provides various wizards to set up your environment, create workloads to host applications and desktops and assign them to users through Delivery groups, using the improved Flexcast 2.0 Management Architecture under the hood.

Delivery Controller… Formerly known as the Zone Data Collector in XenApp or DDC in XenDesktop. It manages user access, distributes desktops and applications and optimizes connections. There can be multiple Controllers per site.

Delivery Agents… Know in XenDesktop as VDA’s but new to XenApp, they replace the IMA service and protocol. DA’s communicate with the site Delivery Controllers, you no longer need to install the XenApp bits and bytes, all you need is a DA. There are two, one for server OS’s and one for desktop OS’s. The server DA supports Windows Server 2008, R2 and 2012, the desktop DA supports Windows XP, 7 and Windows 8. The best thing is, they all communicate with the same controller! This is what makes the diversity in operating systems (as discussed earlier) possible especially for XenApp, both infrastructures under one roof. Delivery Agents in Excalibur are configured via policies.  Any combination of Active Directory GPOs, the Studio console (HDX Policy), and Local GPO settings can be used.

SQL database… We already covered this one, no more IMA for XenApp.

Server OS machines… Physical or virtual machines with a server OS installed intended for publishing applications or hosted shared desktop sessions.

Desktop OS machines… Physical or virtual machines with a desktop OS installed intended for publishing personalized desktops or applications from desktop operating systems. When provisioning VM’s a Host infrastructure needs to be present. Just think of it as a connection to your virtual infrastructure, XenServer or Hyper-V for example. More on this in part 2.

Flexcast 2.0… Already used in XenDesktop but new to XenApp is the Flexcast Management Architecture or ‘FMA’ which replaces the good old IMA. Primarily made up out of the Delivery Agent(s) and Controller(s), it combines provisioning and personalization tools for both desktops and applications. No more separate infrastructures for desktops and applications, it’s one install, architecture and console (Citrix Studio) to meet all your delivery needs. It includes several workflows which simplify and speed up the process of delivering desktops and applications to users.

Windows Server 2012 and Windows 8… It’s obvious but XenDesktop now supports the provisioning of Windows 8 desktops and VM-hosted applications from Windows 8 & hosted shared desktops or applications from Windows Server 2012.

Provisioning / MCS… PVS as we know it is still there, no real changes, MCS however brings some cool new features. Because of the updated Flexcast architecture XenApp Sites are now managed from Citrix Studio which adds the advantage of MCS letting you create new XenApp Catalogs, as well as XenDesktop Catalogs of-course, with a snap of your finger. Updates to the catalog creation wizards in Studio guide you through the initial roll-out of a XenApp Site. Hyper-V version 3 in 2012 introduces some new and improved facilities for accessing storage for virtual machines like the new VHDX format and CSV read caching, have a look here: to see how Excalibur integrates these features.

Intelligent Configuration Validation… Say goodbye to configuration mistakes, Excalibur has an intelligent configuration tool build-in which proactively checks possible configuration errors in real time when deploying desktop and or applications. No more missed steps, how cool is that?!

Profile management… Citrix’s Profile Management has been built into Excalibur. The configuration of Citrix Profile Management, Microsoft’s folder redirection included, is all done from Citrix Studio using the Citrix Policy Engine. When a DA gets installed the Profile Management service will be installed by default as well. It will stay idle if not enabled, when another profile solution is used, but will still offer some nice features. For example, Director uses this service to let you reset Citrix and Microsoft roaming profiles. Next to .INI files and AD Group Policies it’s possible to leverage the Citrix Policy Engine to configure and manage Citrix Profile Management, completely separate from AD if that is your thing. Another addition is the possibility to create and assign Mandatory profiles, a concept well known by all.

Director… Excalibur includes Director, as per Citrix: A troubleshooting solution that grows with your environment. Have a look at:

HDX Edgesite and other HDX improvements… More information on HDX Edgesite can be found on: More on Excaliburs HDX improvements here: and here:

Well… That’s Excalibur in a nutshell (it was a big nut). I hope to have some hardware available soon so I can set-up my own test lab and see how all this holds up in practice. I’ve seen a Blog or two on Avalon and Excalibur, but I liked the idea to talk about all the components and technologies in just a bit more detail.

Bas van Kaam ©

Reference materials used: and the Citrix E-Docs site


6 thoughts on “Project Avalon… Excalibur! Part one”

  1. I have a point to clarify on “No more Terminal Services required on the Delivery Controller” requirement. Does XenApp no longer needs terminal services to work or the requirement to have TS installed on DDC has been removed?

    1. Thank you Henri!

      Have a look at my Blog on the Flex Management Architecture as well, you might find it interesting and helpful for the exam as well. You’ll find it here:

      The best of luck on the exam tomorrow, let me know how it turned out!



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