Hi,
   I am doing some xml-xml transformation.For some of the output elements, if the corresponding source element is null/does not exist I need to set the output to a constant(default value). Is there a way to set default value OR do I have to check if the node exists and if it exists check the length of the enclosed text for zero?

Actually I need to do this for multiple elements. I wanted to look into doing this using templates. Is this feasible with templates? My experience is limited to writing some templates for formatting data. I am eager to do this in the right way.

Thanks,

Templates can only match nodes that exist, they can't match nodes that don't exist. You have to do the work in the template for the parent element (the one that knows it has a missing child). Generally in XSLT 1.0 there aren't any easy short cuts, you just need to write the conditional logic. There are some nice constructs in 2.0, like writing

<xsl:copy-of select="(a, $x)[1]"/>

which outputs a copy of a if it exists, or $x otherwise.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference