Thanks, this is helpful...  I am fairly new to objectscript, so I'm having some difficulty retrieving the filesize from FileInfo from within the customized adapter.  I think I need to call it after a session has been established, and so I'm trying:

Set tFileInfoList=$LISTBUILD("test","test")

do ..%sftpSession.FileInfo(pFilename,.tFileInfoList)

Set tFinalSize= $LIST(tFileInfoList,2)

But this results in an error, ERROR <Ens>ErrException: <UNDEFINED>zPutStream+10^ACH.OutboundAdapterSFTPConfirm.1 *tFileInfoList -- logged as '-' number - @' Set tFinalSize= $LIST(tFileInfoList,2)'

Looking for any info on this error is unproductive.  I must be misunderstanding something about how ByRef arguments work-- likely I am misunderstanding how to invoke FileInfo and handling %List objects for this particular session instance, as well.