inflated Web server stats for PDFs

Charles Dean cdean at
Thu May 18 16:56:48 EDT 2000


I'm seeing strange outliers in our monthly Web server traffic statistics -- 
huge numbers of requests for a given PDF file (usually an e-reserve).  The 
numbers exceed all reasonable accounting for heavy or peak demand during a 
semester.  One file was requested over 24,000 times, when typical traffic 
ranged between 100-300 requests that month for other PDFs.

One library here did some initial testing using Acrobat Reader (3.0 and 
4.0) as both a plug-in and a helper application in Netscape.  They found 
the plug-in configuration resulted in multiple requests to the server for 
"chunks" of the same file, as many as 15 requests/second for PDF files 
larger than 2 Mb.  The helper app config produced a single request per file 
regardless of size.

Granted the test file is a large file (maybe not so large anymore? -- the 
one in production that got 24,000 hits was 5 Mb), but the behavior is a 
little unsettling and would certainly bear on how we interpret our Web 
resource statistics.

Anyone seen anything similar, or know more about the way Netscape/Reader 
treats large PDF files for download and display?

Regards and thanks,


Charles W. Dean
Library Technology Group
University of Wisconsin-Madison
cdean at
(608) 265-2844

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