Fiddler recorded content-length vs WebTest result page bytes

Question

Hi,

I am new in visual studio 2008 Web test. I tried to record to fiddler my web site which deployed in IIS 6.0 and GZIP compression is enabled. I saved the session generated by fiddler to .webtest file extension. I attached the webtest file to vs 2008 and run the web test. I notice that the result of webtest page bytes is different from the content-lenght or body recorded in fiddler.

with GZIP compression:

Webtest bytes vs fiddler body

914,330 vs 45,840

I also try with no gzip compression: This is the result bytes from webtest result: Bytes

Webtest bytes vs fiddler body

1,181,623 vs 406,353

Question: In webtest result, does the column Bytes represent the content-length of the page? if not what does the Bytes column represent?

I also notice that if the GZIP compression is enabled the webtest result response content-length is not shown in the response tab?

Can anyone explain the difference of the result?

Thank you.

Answer 1

Check that the Visual Studio load test is not emulating IE 6 without Gzip compression support. Otherwise check the content header is correct.

Having a look at the traffic captured by fiddler and the playback from a webtest, I would be tempted to put any difference down to the fact that the Visual Studio load test is going to request and record a lot fewer items than fiddler will.

Answer 2

with GZIP compression: This is the result bytes from webtest result:

Bytes

914,330

And this was the result from fiddler:

Body

45,840

I also try with no gzip compression: This is the result bytes from webtest result:

Bytes

1,181,623

And this was the result from fiddler:

Body

406,353

Question: In webtest result, is the column Bytes represents the content-length of the page? if not what is this Bytes column represents for?

I also notice that if the GZIP compression is enabled the webtest result response content-length is not shown in the response tab?

Answer 3

Ok but I'm not yet trying it to load test. I usually check first the webtest that is why I'm wondering that the response content-length of web test is different from fiddler's content-length.