AS2 optional profiles (also “optional AS2 profiles”) are features built into the AS2 protocol but not used by every Drummond certified vendor.  However, the Drummond Group does validate seven different optional profiles (nine total) and these are briefly covered below.

Certificate Exchange Messaging (CEM) – A standard way of exchanging certificates and information about how to use them.

Multiple Attachments (MA) – Simply the ability to transmit multiple files in a single AS2 transmission.

FileName preservation (FN) – Adds metadata to AS2 transmissions to preserve original filenames.  “FN-MA” covers AS2 transmissions without MDNs and “FN-MDN” covers transmissions with MDNs.

Reliability – Provides an application standard around retry, IDs and related matters to prevent double posts.

AS2 Restart – Allows larger files, including those over 500MB, to be sent over AS2.

Chunked Transfer Encoding (CTE) – Permits transmission of data sets that are still being generated when transmission starts.

BEST PRACTICES: The most useful AS2 optional profiles for file transfer are usually MA (multiple attachments) and FN (filename preservation).  Your AS2 software should support all of these.  If you transmit files larger than a few megabytes with AS2, then AS2 restart is also a must.  Other options may be useful on a case-by-case basis.