James Robertson writes

Ed Foster points out that MS - like many other vendors - is forbidding benchmarks as part of their standard contracts:

Is it possible Microsoft has something to hide about the performance of its server and developer products? It's hard to escape that conclusion when you see how many of its license agreements now contain language forbidding customers of those products from disclosing benchmark results.

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So what are MS and the other vendors afraid of?

I'm not sure what the official line is on these contracts but I've come to realize why the practice is popular among software vendors. A lot of the time people who perform benchmarks are familiar with one or two of the products they are testing and know how to tune those for optimal performance but not the others which leads to skewed results. I know that at least on the XML team at Microsoft we don't block people from publishing benchmarks if they come to us, we just ensure that their tests are apples-to-apples comparisons and not unfairly skewed to favor the other product(s) being tested.

Just a few days ago I attended a session at XML 2003 entitled A Comparison of XML Processing in .NET and J2EE where the speaker stated that push based XML parsers like SAX was more performant than pull-based XML parsers like the .NET Framework's XmlReader when dealing with large documents. He didn't give any details and implied that they were lacking because of the aforementioned EULA clauses.  Without any details, sample code or definition of what document size is considered "large" (1MB, 10MB, 100MB, 1GB?)  it's difficult to agree or disagree with his statement. Off the top of my head there aren't any inherrent limitations of pull-based XML parsing that come to mind that should make it perform less than push based parsing of XML documents although differences in implementations makes all the difference. I suspect that occurences like this are why many software  vendors tend to have clauses that limit the disclosure of benchmark information in their EULAs.

Disclaimer: The above is my personal opinion and is in no way, shape or form an official statement of the position of my employer.