NeXus efficiency

[Chris Moreton-Smith]

We did actually discuss this possibility briefly at the SoftNeS'96 meeting when 
Shiming Xu explained that the SDS was added to HDF quite late on to give 
compatibility with (I think) CDF.

The reason for rejecting it was that John Tischler and the X-Ray people were 
thought to be unhappy about people trying to read the HDF data from VDATAs 
rather than "simple" top level SDSs and that a the format would then become 
purely a NeXus format and would leave out the ability for pure HDF access.

For my money I would go straight for Vdatas because it immediately removes the 
two possible ways of storing heterogeneous structured information (in 
attributes and in vgroups) from our implementation if not the interface.  It 
also gives a closer basis to the relational database model as Vdatas are 
analagous to relational database tables.

What does everyone else think ?


> I don't know if they have had more thoughts on the subject, but we didn't
> have enough information at the time to come to a conclusion.  Does anyone
> else have an opinion about whether NeXus might be better implemented as
> Vdata?  This is the sort of decision that we must come to urgently before
> we have problems of backward compatibility.


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