Zeus Traffic Manager - Dynamic rate shaping for slow applications

SearchLimit.pl

# implement the following policy:
 
# if transactions complete within 50 ms, do not attempt to shape traffic.
# if transactions take more than 50 ms, assume that we are in danger of overload and Rate-limit traffic to 100 requests per second, and if requests exceed that rate limit, send back a '204 No Content' message rather then queuing them.
# Once transaction time comes down to less than 50ms, remove the rate limit.


# Create a rate shaping class named "Searchlimit" with a max_rate_per_second: 100
# Create a Service Level Monitoring class named SearchTimer with a response_time of 500 ms.

# We're only concerned with requests for search.  
$url = http.getPath();  
if($url != "/search.aspx") break;  
  
# Time this request using the Service Level Monitoring class  
connection.setServiceLevelClass("SearchTimer");  
  
# Test if any of the recent requests fell outside the desired SLM threshold  
if(slm.conforming("SearchTimer") < 100) {  
   if( rate.getBacklog("SearchLimit") > 0) {  
      # To minimize response time, send a 204 No Content response if the   
      # request exceeds the configured rate of 100/second.  
      # You could also use http.redirect() to a more pleasant 'sorry' page.
      http.sendResponse(204, "No Content", "Cache-control: no-cache");  
   } else {  
      # Shape the traffic to 100/second  
      rate.use("SearchLimit");  
   }  
}