Assistance required with irule for airwatch

OK, this shouldn't be too hard. Any specific reason you want to use CARP? Here's a first attempt;

when HTTP_RESPONSE {
   Check the awcmsessionid header exists
  if { [HTTP::header exists "awcmsessionid"] } {

    If it does, check it has a usable value
    if { [HTTP::header value "awcmsessionid"] != "" } {
      If it does, use it to create a persistence record
      persist add uie [HTTP::header value "awcmsessionid"] 1800
    }
    else {
      log local0. "The awcmsessionid HTTP header was found but is null"
      No luck then, will need to rely on request query string if we can
    }

  else {
    log local0. "The awcmsessionid HTTP header was not found"
    No luck then, will need to rely on request query string
  }
  }
}

when HTTP_REQUEST {
  Check the awcmsessionid header exists
  if { [HTTP::header exists "awcmsessionid"] } {

    If it does, check it has a usable value
    if { [HTTP::header value "awcmsessionid"] != "" } {
      If it does, use it to do a persistence lookup
      If you need to select a pool, do so here, before we persist
      persist uie [HTTP::header value "awcmsessionid"] 1800
      exit here to ensure we don't do two persistence lookups
      return
    }
    else {
      log local0. "The awcmsessionid HTTP header was found but is null"
      No luck then, will need to rely on request query string
    }
  }

  No header so lets use the HTTP query instead, if we can
  Check the right string exists
  if { [string tolower [HTTP::query ]] contains "awcmsessionid" } {

    The required query string is there, let's get it's value
    We'll find awcmsessionid, move one to the right (the =)
    and store data to the end of the query in our variable
    set querystring [findstr [HTTP::query] "awcmsessionid" "1"]
    Lets check its not null
    if { $querystring != "" } {
      persist uie $querystring 1800
    }
    else {
      log local0. "No header or relevant query string found - can't persist"
    }
  }   
}