[Nexus] Basic questions about application definitions

[Carlos Pascual]

Hi Andy,

Here is some info of usage of app defs in the Tango world (you may be 
interested):

-We at Alba implement sardana recorders for 2 application definitions: 
NXscan and NXxas (the first is the default and widely used, and the 
second is a proof of concept that is not in production).  

-We also convert propietary  (t)xrm files from Xradia into NXtomo-
compliant files for interoperability with data analysis programs

-Also, AFAIK the people at Desy are using sardana macros that talk to a 
custom Tango Device which can use the application definition files to 
store data conforming to "arbitrary" app defs.

Cheers, 

Carlos

On Thu 12 February 2015 18:47:36 Andrew GOETZ 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/NXflu
> >> o.html
> >> 
> >> has a typo in it which makes it unusable as it is :
> >> 
> >> *data*: /NXdata/
> >> <http://download.nexusformat.org/doc/html/classes/base_classes/NXda
> >> ta.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
> >> 
> >> 
> >> _______________________________________________
> >> NeXus mailing list
> >> NeXus at nexusformat.org <mailto:NeXus at nexusformat.org>
> >> http://lists.nexusformat.org/mailman/listinfo/nexus

-- 
+----------------------------------------------------+
 Carlos Pascual Izarra
 Scientific Software Coordinator
 Computing Division
 ALBA Synchrotron  [http://www.albasynchrotron.es]
 Carretera BP 1413 de Cerdanyola-Sant Cugat, Km. 3.3
 E-08290 Cerdanyola del Valles (Barcelona), Spain
 E-mail: cpascual at cells.es
 Phone: +34 93 592 4428
+----------------------------------------------------+