In Citrix Application Streaming, the “Application Hub” is the place where streaming profiles are stored.  The streaming profiler writes content to the Application Hub and the streaming client pulls content from the Application Hub at runtime.  Here’s a picture of App Streaming high level infrastructure.  Focus on the box titled “File Server” circled in red, this is the “Application Hub”.  It could also be a web server.

Calling the place where streaming profiles are stored the “Application Hub” is great, it describes the concept and makes it clear that this is the place where streaming content is stored, in the hub!  Marketing folks LOVE IT.  Programmer folks are underwealmed, its a file server.

What gets obscured by the fancy title is that there is ZERO Citrix code running on that server.  This was a design goal from the beginning and we have worked hard to keep that pronciple in place – no Citrix code on the server!   This done both to reduce the number of places we install stuff, but also to follow the model of “keeping it simple”.  Customers already have servers, don’t ask them to put yet another protocol on their network.

The Application Hub stores your applications, but it is YOUR hub.  Any vanilla file server will do or web server.  It doesn’t matter if its SMB, CIFS, Samba, Novell or HTTP, HTTPS, Apache or IIS.  The streaming client will access the content either via UNC based file opens or via a HTTP/HTTPS “get”.  That it.  No extra magic.

Now – you can use your Application Hub (server) to control access to content.  Profiles are on-purpose stored in directories of their own.  Notice that you have a top level directory that holds all your profiles and that you have subdirectories for applications (profiles) below that space.  The streaming profiler absolutely insists that this structure be maintained when profiles are stored.  Why?  So you can DACL protect the entire profile with rights assigned to a single directory.  Its low budget, but it works and administrators are already good at controlling things like this.  Relying on the network/web infrastructure that is already in place makes it easy for the Application Hub to implement things like controlled access, again with the Citrix dev team not having to write any code.  This makes my life happy and I hope this description of the Application Hub takes away the mystery.  Remember though, it is the very grand and glorious “Application Hub” that provides the content for Application Streaming!

Joe Nord

Product Architect – Application Streaming and User Profile Manager

Citrix Systems, Fort Lauderdale, FL