I made a macro which sets the Last-modified http header of Umbraco pages to Umbraco's @updateDate. This caches unmodified pages on the client side, which improves speed and reduces bandwidth on the server. I thought this might be interesting for others, or someone has an even better method?

Below is the basic pinciple. I did make a more advanced version that also takes the updateDate from childnodes, which are displayed as menu items on my pages - so these should also trigger a new Last-modified date. But for clearity, the below example is only for the current page:


<xsl:stylesheet
version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxml="urn:schemas-microsoft-com:xslt"
xmlns:umbraco.library="urn:umbraco.library"
xmlns:msxsl="urn:schemas-microsoft-com:xslt"
xmlns:hua="abc:yoursite-com:xslt"
exclude-result-prefixes="msxml umbraco.library abc">
...

<xsl:value-of select="abc:setModif($currentPage/@updateDate)"/>

...

<msxsl:script language="VB" implements-prefix="abc">
<msxsl:assembly name="System.Web"/>
<!-- assembly reference generates error while saving, so use Skip testing (ignore errors) - not ideal though... -->
<![CDATA[

public Function setModif(dat As String)
Dim mDat As DateTime = Convert.ToDateTime(dat).ToUniversalTime
System.Web.HttpContext.Current.Response.AddHeader("Last-modified", mDat.ToString("r"))
'Return mDat.ToString("r") 'use for debugging
Return ""
End Function

]]>

</msxsl:script>

</xsl:stylesheet>