[ogsa-dmi-wg] Potential problem

[Mario Antonioletti]

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

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|Mario Antonioletti:EPCC,JCMB,The King's Buildings,Edinburgh EH9 3JZ.   |
|Tel:0131 650 5141|mario at epcc.ed.ac.uk|http://www.epcc.ed.ac.uk/~mario/ | 
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