APM Advanced USer Query

it is rather an XML value

You're absolutely right. Not sure why I didn't include the XML in the examples above.

If you've applied the iRule to the virtual server and you have the iRule event agent in the VPE of the access policy, which is also applied to the virtual server, then the iRule above is looking for an event agent ID of "QUERYPROC". When you create the iRules event agent in the VPE, make sure the ID in that agent is in the iRule:

if { [ACCESS::policy agent_id] equals "QUERYPROC" } {
   ...
}

You don't technically have to do it this way, but it's good form and also allows you to have iRules logic applied at different points in the access policy evaluation.