One conversation at OGF20 raised the question of how ByteIO can be used with transport protocols other than those that return data in the response message. The ByteIO spec deliberately leaves this as an extensibility option without specifying how it should be done. It seems to me that it would be too expensive to negotiate a protocol and appropriate mechanism for each request in a multi-request activity. A more practical solution would be to establish some sort of session and then have the ByteIO operations control the transfer across that session. I wonder whether we should mention this possibility in the architecture document? We have deliberately declared session management to be out of scope and I am not suggesting that we go into details, but we could note this as an area for future work. Best wishes, Dave Berry Research Manager, National e-Science Centre 15 South College Street, Edinburgh, EH8 9AA Tel: +44 131 651 4039