Part 1: Working with Citrix XenApp 6.5 – Basic Overview and Components

Basic Overview:

What is Citrix XenApp? XenApp is an application that works on top of what we call TS or Terminal Services to extend the TS functionality.
What is a Terminal Server? Essential a terminal server is a service that allows for multiple/simultaneous users to connect to a centralized server and run applications.
What is ICA? ICA or Citrix Independent Computing Architecture is a very thin/light protocol that is used by XenApp that was developed by Citrix. The ICA protocol operates at the Presentation layer of the OSI model. We will cover the ICA protocol in more detail in Part 2 of this series.
What is IMA? Independent Management Architecture is a protocol that is used for Server-to-Server communication to keep track of licensing, load on the servers, user connections, etc
Four Editions of XenApp server currently exist

1. Fundamentals
2. Advanced
3. Enterprise
4. Platinum

Each of the versions above are limited in the number of features it can support with the exception of Platinum version which has all the features enabled. An overview of what’s available with each edition of the product can be found here.
What is the Licensing model for XenApp 6? The licensing model works based on the number of concurrent users, for example, if there are 100 licenses, that means you can have a total of 100 concurrent/simultaneous users connected at once. The licenses do not tie to a user. Once the user disconnects, the license returns to the pool.
What are the system requirements for XenApp 6? The system requirements can be found on this page.

Citrix XenApp Components:

XenApp Application Server: A XenApp server that hosts/shares applications for users to access
Data Collector Servers: Dedicated servers that are usually deployed in large environments are used for keeping track of server loads, session status, published applications, users connected, and license usage, etc. These servers are typically elected within a Citrix Farm. If a Data collector server were to fail, a new election process would take place to elect a new Data Collector server.
XenApp Farm: A collection of XenApp servers that are used for sharing applications
Web Interface: A web interface used as a webpage/portal for accessing applications that are hosted on a XenApp server
Secure Gateway: A service deployed in the perimeter/DMZ network for situations where users from the outside of the network are trying to access applications hosted on Citrix servers internally
NetScaler: An appliance (Virtual or Physical) which provides level 4 load balancing, content switching, data compression, content caching, SSL acceleration, network optimization, etc
License Server:  A server used for Citrix LIcensing management
Data Store: A centralized database that contains all the configuration information of all the XenApp servers
Local host Cache: a database that resides on all the XenApp servers locally and contains partial XenApp configuration information. The purpose of LHC is for XenApp servers to continue to function if they lose access to the data store.
Worker Groups: A grouping/farm of XenApp servers that are managed as a single unit. The XenApp servers in worker groups typically have similar types of applications installed
Zones: A grouping of Citrix Servers based on their geographic location
Load Manager: A service used to manage the load of all the Citrix servers in the farm. Based on all the XenApp servers that are in the farm, the service will determine the least busy server and redirect the client connections to that server/servers
Resource Manager (EdgeSight): A service used to monitor CPU, Memory, Disk utilization and also create reports based on this information
Access Gateway (VPX, MPX): A virtual or physical appliance used for allowing users on the outside to connect to the XenApp servers on the inside
XenApp Provider: An extension for monitoring that can be used with third party software like SCOM for better monitoring of XenApp servers.
Delivery Services Console (XenApp 6)/AppCenter (XenApp 6.5: Management Console for XenApp servers
License Administration Console: Management Console for managing licenses

Common XenApp Ports:

• TCP 1494 – ICA Protocol
• TCP 2598 – ICA with Session Reliability
• TCP 2512 – IMA communication
• TCP 2513 – XenApp Advanced Console
• UDP 1604 – TCP Browsing
• TCP 80 – XML Service Port
• TCP 443 – SSL Communications
• TCP 8082 – License Management Console
• TCP – 27000 – License Port
• TCP – 5985 – WinRM 2.0
• TCP – 7279 – Citrix Vendor Daemon

XenApp Plugins:

• XenApp Plug-In for Hosted Applications
• XenApp Plug-In for Streamed Applications
• XenApp Web Plug-In
• Client for Java
• Citrix Reciever