Determining Size of Requests & Responses

Question

Hi there,
I'm looking for a reliable and consistent means of determining the size of data transferred between clients and Servlet-based server-side applications over HTTP.
I've been exploring doing this with a Servlet Filter which would attempt to measure the size of the HttpServletRequest and HttpServletResponse objects passing through it.
While I've been able to write code to measure the size of an HttpServletRequest (by inspecting headers and body content), doing so for responses appears to be more error prone, because the HttpServletResponse interface does not expose accessors to items such as headers and status messages.
The only solution I can think of is to use a custom HttpServletResponseWrapper implementation which would track data size of calls to mutator methods such as setHeader() and setStatus().
However, it's not guaranteed that all of the headers and status messages encapsulated in the response, such as those created by the Servlet Engine itself, will be added through the API (rather than the underlying impl), making this approach error-prone at best.
Can anyone suggest a more reliable means of measuring the amount of data being transferred between the client and server tiers?
Any suggestions or comments are greatly appreciated.
Regards,
Sasha Haghani.

Answer 1

Could you not get the content length by extending HttpServletResponseWrapper in this manner:
public class CustomResponseWrapper extends HttpServletResponseWrapper
private int contentLength;
public CustomResponseWrapper(HttpServletResponse response)
super(response);
public void setContentLength(int length)
this.contentLength = length;
super.setContentLength(length);
public int getContentLength()
return contentLength;
Then after the filter is invoked with doFilter, you could get the content length.
Apologies if I'm not understanding your situation.