Integration

Hi All,
In SOA 11.1.1.4, we have a one-way web services which receives message feed from an external Microsoft Biztalk process (caller of the service). However, BizTalk requires even one-way messaging pattern to be able receive a blank response back.

Questions*
1) Is there a way to configure at my end on Oracle SOA working having one-way messaging pattern send a blank response back?
2) If not the only way go is change one-way to request/response, here I defined a response element as a string which I hope to send back. I want to populate the string with some value which proves to be useful later. Is there any such property value to track messages based on id or something? My current composite is Web-Service (request/response) --> Mediator --> DBAdapter. Here how do I assign a value to the response type (XML string element).

Hope I make sense, please suggest solutions for the above two questions

Thanks