Code Camp 2017¶
NeXus Code Camp - 24th to the 26th of October, 2017¶
Location: The Cosener’s house, Abingdon UK¶
Agenda¶
Tuesday¶
Morning¶
Shape descriptions (Dean Keeble and Tim Spain will be visiting)
Afternoon¶
C++ wrappers for HDF5
Versioning
After Coffee¶
Features
Example files for Ray.
Evening¶
6:00 - 6:30 pre dinner drink
7:00 - Dinner at cosners house
Main-Course: Rack of lamb with rosemary crumb, dauphinoise potato, chargrilled courgette, vine roasted cherry tomato, fine bean parcel and rosemary jus
Vegetarian Option: Asparagus and broad bean risotto, parmesan tuile and lemon balm
Pudding: Classic glazed lemon tart, crème fraiche and berries
Wednesday¶
Morning¶
PDB integration (Greame Winter and Charles Mita will be visiting)
Dealing with dropped frames
Afternoon¶
3pm VC with Pete on Versioning
Detectors with modules in modules. (Aaron Brewster may be VCing in)
Evening¶
Reservartion for 7:00 at wildwood
Thursday¶
Morning¶
Event data (Alan Greer also attending)
Event log disscussion and focus on example files.
Afternoon¶
Wrap up and Telco
The aim is to start at 10:00 on the 24th, 9:00 the other days and finish early afternoon on the 26th.
Minutes for the meeting¶
Tuesday Morning¶
Introductions
Move the PDB and versions to the afternoons so that Pete Jemian can VC in
First item is to investigate the shape methodoloy as investigated by the ESS team
There is concern over how the shape can accurately describe detectors, and how the data is mapped to the shape.
Visualisation is important, but so it the use of full descriptions for analyis
The OFF format will be used for Mantid and McStas
A new description for Quadrics will be developed by DLS to deal with more complex descriptions for use with xrmc. There should be a converter for this to the OFF NeXus description.
Tuesday Afternoon¶
2 Seperate threads
Versioning¶
Looking at the versioning concept as in the document
Big discussion about the complexity of local vrs. global versioning, i.e version on baseclasses vrs. versioning on the file.
Came to the conclusion of a single version number which increments gradually and incrementally to deal with new versions.
Things to do
UPDATE WORKFLOW - Questions here, but we will try to address at the code camp.
VERSIONING SEMANTIC - Big changes bump version by 1
VALIDATION - is easier now as there is only one global version to validate against
LEGACY DOC - Still in the repository.
C++ wrappers for HDF5¶
On ess-dmsc github h5cpp
Came out of some HDF work, didn’t like the C++ API.
Various parties were doing their own - Tobias asked them to work together.
Eugen and Martin, ocassionally Jonas Nilison
Auto builds docs, doxygen
Migration of Eugen PNI code at the beginning. Lack of tests, now adding more tests.
Aim to cover all of HDF5 features, e.g. SWMR, compound data types etc.
Examples of implementation: write_simple_vector
Suggest to use clang format.
Using google’s style guide - need consistency
Fortnightly meetings
Implemented types: basic types int, float etc.
Going to be used in the file writer
Trying to make it as easy to use as h5py
Looked at internal Paths
Plan to create performance tests
Will put on to conan
Martin will replace the naïve version he is currently using.
Detector people are interested in using it to store diagnostic data.
Happy to take suggestions for things to be implement from other parties.
Discussed using in-memory files for performance tests
Setting up Windows automated build and hoping to OSX
MPI support in the future?
Using runtime exceptions - should it use something more tailored? Do something with the hdf error stack
Wednesday Morning¶
NXmx PDB discussion¶
It was decided that NXmx could easily contain an NXpdb which contains the basic information required for PDB ingest
Charles Mita from DLS will make a first pass at this for VMXi data
Dropped frames¶
could the value be set to NXdetector.undefined, or NXdetector.saturation_value
Could the count_time value be set to zero (or annother value) for the frame which is not there.
a valid count time is anything zero or above, anything other than this is an invalid frame.
The solution was to create a new dataset called frame_acquired
a boolean dataset
True if the frame is correcly collected, if the frame has been dropped by the datawriter and padded with fill value, then this shoud be set to False
The fill value should be set to a value larger than the NXdetector.saturation_value
Wednesday Afternoon¶
Features¶
We all continued to work on features.
Versions revisitited with Pete¶
It was agreed that Base class versions were not that useful, and so these can be made optional to inherit from the main version
Agreed with the concept of global versioning
in the January release the version numbers will move to Year.Month instead of 3.4
Modules in Modules, with Aaron Brewster.¶
Seems like a sencible option
TASK on AB to update the documentaion on modules to clarify the usage of the depends-on and pixel size
TASK on AB to make an NXlog index class for multiple event streams.
Thursday Morning¶
Discussion on NXevent_data
Continue on features
