How does JON measure web application response times?
The JON uses a Servlet Filter to intercept all requests made to a monitored web application. The steps to configure the servlet filter and the other required resources are provide on the Servlet Product Configuration page. The main execution steps for the normal operation of the filter’s doFilter() method are as follows: • Get the current system time. • Call doFilter() on the next filter in the chain. • Get the current system time, use that to calculate the elapsed time for execution of the call in step 2). (This value is what is called the Response Time). • If the buffer is too large or too old make a synchronised call to flush the buffer to the response time log file. The buffer age is configured via the filter init-param bufferTime and the size by the init-param bufferSize. • Update metrics on the MBean for the particular servlet rendering this request, i.e. availability, request count, max processing time, min processing time, total processing time, error count. • Update metrics on
