[Nexus] Basic questions about application definitions

[Osborn, Raymond]

Perhaps the real story is that we have not made much progress over the last few years on validation tools that would automatically catch issues like the one Andy raised. That was discussed at the last NIAC, and I think we should see some useful developments over the next year.

Ray

On Feb 12, 2015, at 11:47 AM, Andrew GOETZ <andy.gotz at esrf.fr<mailto:andy.gotz at esrf.fr>> wrote:

Dear Tobias + Pete,

thank you both for your quick replies. They clarify the situation a lot.

I understand it is difficult to know who is using the application definitions but maybe a survey could be done on the mailing list to find out how many use which application definition and which software implements them.

Regards

Andy

On 12/02/2015 18:07, Tobias Richter wrote:
Dear Andy,

To answer your first second question first (before I forget): I have not come across anything in NeXus that requires you to duplicate data. Linking is always allowed. There are some opposite cases like the one you quote below, where linking is mandated in a particular way. In my view that’s more of a legacy item. As long as data can be retrieved from the specified location using the underlying contain format, I don’t care how it gets there.

Otherwise Pete has written something on subentry that may help. If it doesn’t speak up!

The majority of the application definitions where generated at some point far back in time with the best intentions. You have to start somewhere, right? Most facilities are only now slowly taking up the task to implement them (fully). When problems are found we try and resolve them. Unfortunately there is not yet an army of volunteers out there that implements and tests everything for us.

Regards,

Tobias


On 12 Feb 2015, at 17:39, Andrew GOETZ <andy.gotz at ESRF.FR<mailto:andy.gotz at ESRF.FR>> wrote:

Hi,

at the ESRF we were looking at the application definitions and saw by chance that the fluorescence one:

http://download.nexusformat.org/doc/html/classes/applications/NXfluo.html

has a typo in it which makes it unusable as it is :


data: NXdata<http://download.nexusformat.org/doc/html/classes/base_classes/NXdata.html#nxdata>

energy –> /entry/instrument/fluorecence/energy

data –> /entry/instrument/fluorecence/data

This begs the question : how many sites are using the Application definitions and how do you get around the bugs?

A second question we had is that the way the application definitions are defined today implies they duplicate data in the file instead of linking to it. This is because they insist on creating NXsubentry. Please correct me if we have misunderstood the use of NXsubentry.

Our second question is : does this bother anyone else than us?

Kind regards

Andy + Christophe


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--
Ray Osborn, Senior Scientist
Materials Science Division
Argonne National Laboratory
Argonne, IL 60439, USA
Phone: +1 (630) 252-9011
Email: ROsborn at anl.gov<mailto:ROsborn at anl.gov>


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