Use case 13: Configure XenApp for load balancing

For efficient delivery of applications, you can integrate the NetScaler appliance with Citrix XenApp and use the NetScaler load balancing feature to distribute the load across the XenApp server farms. The following figure is a topology diagram of such a setup.

Figure 1. Load Balancing of XenApp

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The Web Interface servers provide secure access to XenApp application resources through the user’s Web browser. The Web Interface client presents to the users all the resources, such as applications, content, and desktops that are made available in the XenApp server farms. Users can access the published resources through a standard Web browser or through the Citrix online plug-in.

The Web browser on the user’s device sends information to the Web server, which communicates with the servers on the server farm to provide the user with access to the resources.

The Web Interface and the XML Broker are complementary services. The Web Interface provides users with access to applications, and the XML Broker evaluates the user’s permissions to determine which applications appear in the Web Interface.

The XML service is installed on all the servers in the server farm. The XML service specified in the Web Interface functions as an XML broker. On the basis of the user credentials passed by the Web Interface server, the XML Broker server sends a list of applications accessible to the user.

In large enterprises where multiple Web Interface servers and XML Broker servers are deployed, Citrix recommends load balancing these servers by using the NetScaler appliance. Configure one virtual server to load balance all of the Web Interface servers and another for all of the XML Broker servers. The load balancing method and other features can be configured on the virtual server as required.


Although you can use the HTTP protocol, Citrix recommends that you use SSL for communication between the client and the NetScaler. You can use the HTTP protocol for communication between the NetScaler and the WI servers even though you use the SSL protocol for communication with the client.

To configure load balancing for XenApp by using the GUI

  1. Create a service.
    1. Navigate to Configuration > Traffic Management > Load Balancing > Services and click Add.
    2. Create a service by specifying a name, an IP address, a port, and a protocol type and then click OK.
  2. Create a load balancing virtual server.
    1. Navigate to Configuration > Traffic Management > Load Balancing > Virtual Servers and click Add.
    2. Create a virtual server by specifying a name, an IP address, a port, and a protocol type and then click OK.
  3. Bind the service to the load balancing virtual server.
  4. Navigate to Configuration > Traffic Management > Load Balancing > Virtual Servers and select a server.
    1. Click Edit.
    2. In the Services and Service Groups, click > and click Add Binding.
    3. Select the service you want to bind and enter the weight value.
    4. Click Bind.

To configure load balancing for XenApp by using the command line interface

  • To create a service, at the command prompt, type:
add service <name> <serverName> <serviceType> <port>


add service Service-HTTP-1 HTTP 80
  • To create a virtual server, at the command prompt, type:
add lb vserver <name> <serviceType> <ip> <port>


add lb vserver Vserver-LB-1 HTTP 80
  • To bind a service to a load balancing virtual server, at the command prompt, type:
bind lb vserver <name> <serviceName>


bind lb vserver Vserver-LB-1 Service-HTTP-1
Use case 13: Configure XenApp for load balancing