Distribute load based on uri

 when RULE_INIT { 
    set counter 0 
 } 
 when HTTP_REQUEST { 
     if {$::counter <= 7} { 
      The first 7 requests are redirected to  URI 1 
       HTTP::redirect "http://uri1" 
       incr $::counter 
    } elseif {$::counter <= 10 } { 
       The next 3 requests are redirect to URI 2 
       HTTP::redirect "http://uri2" 
       incr $::counter 
    } else { 
      Reset counter and send the 11th request to URI 1 
      set $::counter 0 
       HTTP::redirect "http://uri1" 
    } 
 }