irule for xml content based parsing

You need to apply an XML profile in which you specify the XPath that you are looking for, then use an iRule to perform the pool assignment based on that. The $XML_count, $XML_values etc are created by the XML profile and contain the details of the matched XML elements.

Use this for guidance: https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-implementations-11-2-0/3.html

when XML_CONTENT_BASED_ROUTING {
  for {set i 0} { $i < $XML_count } {incr i} {
    log local0. $XML_queries($i)
    log local0. $XML_values($i)
    if {($XML_queries($i) contains "FinanceObject")} {
      pool finance_pool
    }
  }
}