What is Citrix XenApp?
Citrix XenApp is a remote access publishing platform that allows users to connect to their business applications, available from XenApp servers located in central locations (as Data Centers). Applications can be open it in these XenApp servers, using server hardware (CPU, Memory, hard disk, etc), and images are send to user client devices, instead to the server screen. A XenApp client shows the XenApp published applications to users like a local installed application.
XenApp it is a recently name given by Citrix, renamed from Presentation Server, which was originally known it as Metaframe. Citrix renamed the product due inclusion of many features which gave it new functionalities and to create a "line" of virtualization products, which includes XenDesktop and XenServer.
According Citrix, XenApp means:
Xen = Virtualization
App = Application
XenApp = Virtualized Applications
One XenApp server can support many users, generally from 30 to 80 users, depending of the XenApp server hardware specs, application requirements to run and user usage. A set of XenApp server constitute into a Citrix XenApp Farm. A farm can have around 5000 XenApp servers, supporting thousands and thousands of users.
To use Citrix XenApp, you need Windows Servers with Terminal Services capabilities and install specific Citrix XenApp client on user machines. XenApp versions have different features, going from Standard/Advanced to Platinum, with more configuration options and integrated products. XenApp client installations will depend of which operational system you will use on client computers, and can be Windows (all versions), Linux, Dos, Mac Os and others.
XenApp uses an owned protocol called ICA (Independent Computing Architecture), on port 1494, to provide fast and reliable connections. ICA compression is very impressive and enable companies to use very limited bandwidths to provide secured applications with XenApp with a good user perception.
Mainly advantages to use Citrix XenApp:
- Seamless user experience on any device from anywhere. Depending how user access is configured, users will not distinguish if applications are installed local on their machines or on Citrix XenApp servers.
- Minimizes cost with hardware on user clients machines. Since applications are running from XenApp servers
- Can secure all business information in centralized application storage, delivering only to authorized persons from anywhere on any device. Almost devices in the world support XenApp clients.
- Mobility, giving access to applications from anywhere, reducing employee costs by eliminating unnecessary commutes to the office and creating an efficient platform for work from home or travelling.
- Improves employee job satisfaction with opportunity for more flexible work environments.
- Reduces resources and costs for application distribution and management. After install applications on Citrix XenApp servers, you can easily make these applications available to XenApp users.
- Minimizes impact of server failures with real load-balancing and improves application response with resources to optimize CPU and Memory on XenApp servers. During a user connection to a XenApp environment, if one XenApp server is not available, users are automatically redirected to other available XenApp server.
- Good security provided by SSL encryption supported and owned very good encryption on ICA protocol.
- Give flexibility to the company, allowing instant deployments of new applications or new users. A company using a full proposed and well designed solution can deploy new users in just few minutes.
Example of Citrix XenApp utilization
A new user is hired in a remote site of a company and needs a computer with Microsoft Office, SAP and some legacy applications using a dedicated and limted WAN link. IT department can create his domain and email account and associate domain groups to give him access to XenApp published applications. Then, IT department can send by post a Thin Client to user with instructions about how to plug mouse and keyboard, and how to turn on the device. After turn on the ThinClient, user will asked for his domain credentials and will see a Windows XP interface (blocked to any user software installations) and with all application icons in Start Menu, ready to work.
If for some reason, a XenApp server has a problem, when opening a new application, user will be automatically redirected to other healthy XenApp servers. If user workstation (ThinClient) has a problem, the same user can input his credentials in any other company workstation and have all same interface, applications and files. And if this user is going to visit an external location, he can easily keep one eye on his XenApp applications using his mobile.
If this company decide to migrate all 10.000 users from Microsoft Office 2003 to Microsoft Office 2007, the job can be done in just few hours in a weekend. IT team needs just deploy the new Office into XenApp farm, if everybody in company it is using Citrix XenApp.