Applying two transforms to a message on the send port

I have an urgent need to send a canonical message (M1) out of an orchestration and need to map the canonical message to another message (M2). The resulting message (M2) has to be Wrapped in another request 开发者_运维百科message (M3) before sending it to a web service.

I can't perform the initial transform in the orchestration as I can only deal with the canonical schema internally.

Whats the best way to achieve this 2 stage transform outside of the orchestration?

Thanks in advance!

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You could make a pipeline component that applies each map sequentially. Then configure the port to use a pipeline with this component.

private Stream ApplyMap(Stream originalStream, Type mapType)
{   
   var transform = TransformMetaData.For(mapType).Transform;
   var argList = TransformMetaData.For(mapType).ArgumentList;

   XmlReader input = XmlReader.Create(originalStream);
   Stream outputStream = new VirtualStream();

   using (var outputWriter = XmlWriter.Create(outputStream))
   {
      transform.Transform(new XPathDocument(input), argList, outputWriter, null);
   }
   outputStream.Flush();
   outputStream.Position = 0;

   XmlReader outputReader = XmlReader.Create(outputStream);
   return outputReader;
}

Then in the pipeline component's Execute method:

Type mapType1 = Type.GetType("YourMapNamespace.Map1, YourAssemblyName,...");
Type mapType2 = Type.GetType("YourMapNamespace.Map2, YourAssemblyName,...");

Stream originalStream = inmsg.BodyPart.GetOriginalDataStream();
Stream mappedStream = 
   ApplyMap(
     ApplyMap(originalStream, mapType1),
     mapType2
   );
inmsg.BodyPart.Data = mappedStream;
context.ResourceTracker.AddResource(mappedStream);

Note that this example does everything in memory so it could be a problem for large messages. I'll try to find a better example that uses streaming (or worse case, you can use VirtualStream to avoid keeping everything in memory)

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If you can use the ESB Toolkit, the ideal approach would be to use an itinerary (Richard Seroter has a good article on that approach here). If that's not an option, here's an approach I've used in the past:

http://blogs.msdn.com/b/chrisromp/archive/2008/08/06/stacking-maps-in-biztalk-server.aspx