hi,
as i was asked to send it during irc chat but before talking about identification: i recommend this article: Evolution of Web Services Attachments Technologies (Canyang Kevin Liu and Sanjay Patil)
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/documents/a1-8-4/Evolution%20of%20Web%20Services%20Attachments%20Technologies.article
it does very good job of going though history of WS with attachments and comparing approaches
about identification: i thin that relying on transport to have type="application/xop+xml" in transport packaging should be enough (for HTTP it is: Content-Type: Multipart/Related;boundary=MIME_boundary; type="application/xop+xml";)
if XOP is detected then XOP Infoset is first created then it is later (at least in logical sense) resolved to "Original" Infoset - in infoset view there is no difference between BASE64 that is just text and one backed by binary attachments so there is need for OM API to identify (OMBlob?) and deal with very large attachments (stream in/out of fles like in AXIS1 and/or make it extensible)
alek
-- The best way to predict the future is to invent it - Alan Kay
