Article ID: 293099 - View products that this article applies to.
This article was previously published under Q293099
After an Extensible Markup Language (XML) or Extensible Stylesheet Language (XSL) document has been cached on a client computer, subsequent requests to use the file may result in an unnecessary "If-Modified-Since" GET request to the server if the file has not expired. These extra requests slow down the performance of high-scaled servers and large applications.
To resolve this problem, install Microsoft XML (MSXML) Parser version 3.0 or later, and use the XmlInst.exe tool to install MSXML 3.0 in Replace mode. When you run XmlInst.exe to install MSXML 3.0 in Replace mode, all application references (including those for Internet Explorer) are remapped to point to MSXML 3.0. If you do not install MSXML 3.0 in Replace mode, Internet Explorer continues to use MSXML.dll instead of MSXML3.dll, and the problem continually recurs.
You can download MSXML Parser version 3.0 from the following Microsoft Web site:
http://www.microsoft.com/downloads/details.aspx?FamilyID=8167837e-0983-4988-99a4-377ef5c0da2e&DisplayLang=enFor more information, click the following article number to view the article in the Microsoft Knowledge Base:
269238You can download the Xmlinst.exe Replace Mode tool from the following Microsoft Web site:
(http://support.microsoft.com/kb/269238/ )Version list for the Microsoft XML parser
Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the "Applies to" section.This bug was corrected in MSXML Parser version 3.0.
When Internet Explorer downloads and caches content, if the server has specified an expiration time for the content, Internet Explorer should not send "If-Modified-Since" GET requests to the server to check for content updates until after the expiration date and time have been reached (which is indicated in the expiration header). Internet Explorer should only send an "If-Modified-Since" GET request to check with the server if the content is expired. However, with MSXML.dll (and thus with .xml and .xsl files), an unnecessary "If-Modified-Since" GET request is sent even if the .xml or .xsl file has not expired.
If all the files are loaded in the cache because of a previous visit to the site, and if the files have not expired, this bug can be observed in several different circumstances:
For more information about how to resolve the third issue, click the following article number to view the article in the Microsoft Knowledge Base:
308603At this time, there is no resolution for the fourth issue.
(http://support.microsoft.com/kb/308603/ )The DomDocument Load method ignores content expiration
For more information about how to install MSXML 3.0 in Replace mode, see the following Microsoft Web site:
http://msdn.microsoft.com/library/en-us/xmlsdk/html/c8c3527c-991c-4cb1-b3e1-b810ebade4a1.aspFor more information about the XML DOMDocument object, see the following Microsoft Web site:
http://msdn.microsoft.com/library/en-us/xmlsdk/html/39b17b9c-04c7-4fa8-bcee-1f7d57eefd74.aspFor more information about developing Web-based solutions for Microsoft Internet Explorer, visit the following Microsoft Web sites:
Article ID: 293099 - Last Review: May 11, 2006 - Revision: 4.0