[Nexus-developers] data type for binary data

[Vicente Sole]

Hi,

I am also of Tobias opinion.

Best regards,

Armando

Quoting Tobias.Richter at diamond.ac.uk:

> Hi Freddie,
>
> I'd propose to leave NX_BINARY alone and just add NX_OPAQUE.
> Does not break any existing files or code. And developers can switch  
>  to the new functionality when ever they want.
> They are only ever forced to change if they want to read a file with  
>  NX_OPAQUE. The only Nexus class that requires NX_BINARY is the data  
>  in NXnote as far as I can see. We should be able to allow NX_OPAQUE  
>  in there as well then.
>
> Regards,
>
> Tobias
> ________________________________________
> From: nexus-developers-bounces at nexusformat.org   
> [nexus-developers-bounces at nexusformat.org] on behalf of   
> freddie.akeroyd at stfc.ac.uk [freddie.akeroyd at stfc.ac.uk]
> Sent: 07 December 2011 01:10
> To: nexus-developers at nexusformat.org
> Subject: Re: [Nexus-developers] data type for binary data
>
> Hi Eugen,
>
> I think it would be good if we could use the HDF5 binary type as it   
> properly distinguishes "UInt8" and "binary data", but we would need   
> to add some support into NeXus to handle such data via the API and   
> there are some compatibility issue we need to assess too.
>
> If we change NX_BINARY to Opaque, then a recompiled nexus program   
> that reads a previously written binary array (UInt8) and checked its  
>  type was "NX_BINARY" would fail. Similarly a newly compiled program  
>  writing NX_BINARY to read in by an hdf5 aware non-nexus program may  
>  find that changing from UInt8 to OPAQUE breaks something there. If   
> we think these are likely, then one option is to remove NX_BINARY   
> and add NX_OPAQUE instead - programs using NX_BINARY would then fail  
>  to compile and must decide on UInt8 or opaque (purely relinked   
> programs would still work though via the previous UInt8 definition).  
>  What do people think?
>
> Regards,
>
> Freddie
>
> -----Original Message-----
> From: nexus-developers-bounces at nexusformat.org   
> [mailto:nexus-developers-bounces at nexusformat.org] On Behalf Of Eugen  
>  Wintersberger
> Sent: 05 December 2011 10:15
> To: nexus-developers at nexusformat.org
> Subject: [Nexus-developers] data type for binary data
>
> Hi folks
>   I am actually implementing the binary field type for my C++ API.
> According to the Nexus documentation binary data is stored as UInt8
> which has historical reasons.
> HDF5 provides now an opaque data type which indicates already on HDF5
> level that the data is uninterpreted binary. Thus I would rather use
> this data type than UInt8.
> Is this ok according to Nexus or shall I use UInt8 for backward
> compatibility?
>
> regards
>    Eugen
>
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