Biztalk Preload output message before Map transform

Question

I have 2 correlated incoming messages from 2 different systems (SystemA and SystemB) and I just want to basically copy over a couple fields from the SystemA message to the SystemBmessage.

So my Construct Message shape looks like this:

The Message Assignment shape just has this code inside it:

xmlIncomingNoAttachHolder = new System.Xml.XmlDocument();
xmlIncomingNoAttachHolder = msgMultiPartInNoAttachment.BodySegments;

// assigning the SsytemB version (no attachment) first.
// Also, since we are only copying a couple fields, this can serve as the base.
msgComboWithAttach = xmlIncomingNoAttachHolder;
msgComboWithAttach(XMLNORM.TargetCharset) = "UTF-8";

The map then just has the 2 input (SystemA schema and SystemB schema) ORU messages on left and the output ORU message on the right, which also shares the same schema as the SystemB input message.

My hope was that I could just use the message assignment code above to assign the Output msgComboWithAttach message, then use the mapper to map over the few fields that we need from the SystemA message to the SystemB message.

But it seems that as soon as I apply the map, it clears the pre-loaded msgComboWithAttach message before performing the transform and then applies the map. The resulting message then contains ONLY those fields that are copied over in the map and none of the other segments/fields that were assigned in the message assignment pre-load.

Is this expected behaviour, in which case, I would have to do a Mass-Copy on all the segments in the Map? Or is there a way to pre-load/copy the message like I want and then only Map a couple fields over?

Answer 1

Yes, that is the expected behavior since the transform will create a new message. You cannot use Xslt to modify a document in that way.

Dijkgraaf's solution will work. As an alternative, you can use the Orchestration xpath() function to read and set specific values in Message. See: http://msdn.microsoft.com/en-us/library/ee268159(v=bts.10).aspx