Hi all, quick shot at face value: I don't see a problem - I see this as an implementation detail. Primarily, I see this problem as a fault of the sink not DMI, as the sink returns an available protocol that effectively is impossible to use (setting temporal skews aside). Naïve DMI implementations may simply go forward and trust the information supplied by source and sink, while more advanced implementation may be able to solicit that information with heuristics, statistical/historical information and active probing as you described. Cheers, Michel On 5 Nov 2007, at 16:04, Mario Antonioletti wrote:
Hi, Last week we were discussing comments to the OGSA Data document and something came up that is pertinent to DMI (Alle pitch in).
Basically, suppose that the source and sink publish a set of supported transport protocols. Then, if client wants to effect a transfer between the source and sink, they would talk to a DTF. The DTF would negotiate a protocol supported at both ends and create a DTI to manage the transfer for the user. The issue is that there may be other factors that preclude that transfer from taking place - for instance as a simple example, if active ftp was chosen as the protocol of choice a firewall could stop this transfer from successfully completing. The DTI would not be able to communicate this back to the DTF as the two are logically dissociated. Is there an expectation that the DTF, would not only protocol match but also test out that the transfer protocol actually works between source and sink before creating the DTI? I'm not sure if this is an implementation thing or whether there is a deeper potential problem here - thoughts?
Mario
+--------------------------------------------------------------------- --+ |Mario Antonioletti:EPCC,JCMB,The King's Buildings,Edinburgh EH9 3JZ. | |Tel:0131 650 5141|mario@epcc.ed.ac.uk|http://www.epcc.ed.ac.uk/ ~mario/ | +--------------------------------------------------------------------- --+ -- ogsa-dmi-wg mailing list ogsa-dmi-wg@ogf.org http://www.ogf.org/mailman/listinfo/ogsa-dmi-wg