In the sample web app for the preview webservice in Tridion 2013 the web.config file has the following:

  <add name="Tridion.ContentDelivery.AmbientData.HttpModule" 
       type="Tridion.ContentDelivery.AmbientData.HttpModule" />

while in the documentation, you are instructed to add this element with the attribute preCondition="managedHandler" Does this matter? Presumably it only makes a difference if you access non-managed resources. Is one setting better than the other? Is it better to regard the installation guide or the sample as leading?

1 Answer 1


I might be wrong, but I think the main net effect of using preCondition="managedHandler" is that the module will only be executed on requests for managed resources (ASPX, ASCX, etc) and not for static resources (.gif, .css, etc).

You typically want ADF only to load on "dynamic" resources (your pages) and not on every request to any asset, but this depends on what you're doing with it. You could want to execute the ADF pipeline everytime a CSS is loaded (not that I think you should, but you could), so you have the option to define it yourself.

Why is it in the sample and not in the documentation? No clue. Developers didn't think it was important enough?

  • So reading between the lines, for a vanilla install, you should set this attribute, right? May 6, 2013 at 18:47
  • Yes. If you don't know what it does or if you need it, it probably means you should use it. :)
    – Nuno Linhares
    May 6, 2013 at 18:51
  • Should this also be applied to the PreviewContentModule module in the web.config of a vanilla install too? May 7, 2013 at 15:13

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