Anon,
I’m not sure whether you’re after something a little more low level than this, but….
I would have a map from your SAP request message (the message that is being sent to your Orchestration exposed as a web-service) to the request message that BizTalk will be sending to the external web-service. In this map you will be adding the detail from the SAP request to your head/footer external message request.
You will then call the external web-service within your orchestration using a request/response port (sending the newly built external request message).
A second map in your orchestration will then map the external web-service response back to the SAP response, which will be send back via the request/response port that is used to expose your orchestration as a web-service.
Alternatively….
Expose the schema that the SAP web-service is consuming as a web-service (instead of your orchestration); subscribe to the MessageType of this schema with a Send Port that consumes your external web-service. On this Send Port use the first map (above) on the Send side and the second map on the receive side of the port and you have a messaging only solution – no need to host an orchestration!
For the messaging only solution, take a look at the following for more information:
- http://www.digitaldeposit.net/blog/2006/12/biztalk-2006-soap-adapter-web-service.html
- http://blogs.msdn.com/richardbpi/archive/2006/11/10/using-only-biztalk-messaging-with-request-response-on-both-ends.aspx
- http://msdn.microsoft.com/en-us/library/aa560545.aspx
You will also be consuming web-services without web-references:
HTH, Nick.