By default, when creating a XenMobile load-balancer Service or Service Group on a Citrix NetScaler, the “tcp-default” monitor is applied. That is not sufficient to determine if the XenMobile service is really available or not, so, Citrix NetScaler provides the ability to create custom monitors to ascertain the health of its load-balanced services. The XenMobile Server product runs on a distribution of Linux Kernel 3.4.49 Long-Term Support, and doesn’t expose a lot of information for a Microsoft guy such as myself. There are online resources for how to construct the custom monitor, but with the new versions of XenMobile, the expected “Receive String” (and how it is processed by the NetScaler) keeps changing and that is not well-documented at this time.
So, here are some things to consider when creating the Advanced Monitor of type HTTP-ECV for XenMobile on the NetScaler. You would “Add” a new monitor in Traffic Management | Load Balancing | Monitors from the NetScaler console. Name it “XenMobile-Advanced” (or something appropriate to easily indicate what it is) and select the “Type” of “HTTP-ECV” from the drop-down menu. Keep the “Standard Parameters” at their default values, but click on the “Special Parameters” tab and enter the following Send String and Receive String as below. No “Customer Header” is required. A screenshot of the “Special Parameters” is included.
The “Send String” is the same for each of the XenMobile versions:
The “Receive String” will change depending on the version of XenMobile. Enter it exactly as below.
For XenMobile version 9.x, this string works:
For XenMobile version 10.1, this string works:
For XenMobile version 10.3, this string works:
Additionally, you can add a “Response Code” of 302 to the “https” monitor included with the NetScaler monitors in the “Special Parameter” section of the “https” monitor. This monitor performs a full SSL handshake to determine if the service is operating properly. So, whether you get a “200” or a “302” response, it will be valuable in determining if the service is available. A screenshot is also included for updating the “https” monitor.
Here’s a screenshot of the “Special Parameters” configuration of the XenMobile Advanced monitor, which uses HTTP-ECV as its monitor type. The “Standard Parameters” are default values.
Here’s a screenshot of the updated “Special Parameters” configuration for the https monitor of the “HTTP” type. The “Standard Parameters” are the default values.
Here’s the blog from Citrix about the Advanced Monitor:
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