On either the initiator or responder computer, the back-end LOB application routes a message to the MessagesFromLOB table of the BTARNDATA SQL Server database. BTARN uses a SQL adapter to move the message from the MessagesFromLOB table to the private process. For more information, see "SQL Adapter" in BizTalk Server 2006 R2 Help.
You can choose to use a File adapter to submit service content to BTARN, instead of using the default SQL adapter. If you choose to use a File adapter, BTARN does not support attachments.