XML comment in BizTalk output message

We ran into an issue today when we had to have an XML comment just below the XML declaration in a message we’re producing in our BizTalk 2006 solution. We needed to produce something like the below.

<div><span style="color: #0000FF; "><?</span><span style="color: #FF00FF; ">xml version="1.0"</span><span style="color: #0000FF; ">?></span><span style="color: #000000; ">
</span><span style="color: #008000; "><!--</span><span style="color: #008000; "> Comment goes here </span><span style="color: #008000; ">--></span></div>

Our first approach was to create a map in the send port and to have a custom XSLT template in there that added the comment before the whole transformation process started. We actually got this to work but it meant that we had to have a whole new map with a separate XSLT document in the project!

Eventually we found a property called Xml Asm Processing Instructions (highlighted in the figure - click it to view it in original size) on the XML assembly component (used in the standard XMLTransmit pipeline).

We just put the comment as a value in this property and we were done! No new artifacts or code! Just a weird property - typical BizTalk behavior!