UPDATE: I have since moved these articles to my own blog and they can be found here.
I just posted another article for TopXML.com as part of my series on BizTalk + WCF. This post digs into exposing WCF services out of BizTalk that utilize security features, MTOM attachments, and transactions.
Topics include: message-based security, transport security, custom role based authorization, MTOM attachments, and how to send messages to BizTalk as part of a client transaction. I observed some odd behavior with regards to MTOM where the “request” on the request/response port correctly attached the binary content as a MIME part, but the “response” message kept the binary string inside the XML payload itself.