Authors: Jan Kotanski, Eugen Wintersberger, Halil Pasic
NXSDataWriter is a Tango server which allows to store NeXuS Data in H5 files.
The server provides storing data from other Tango devices, various databases as well as passed by a user client via JSON strings.
Tango Server API: https://nexdatas.github.io/nxsdatawriter/doc_html
Install the dependencies:
Download the latest NexDaTaS version from
Extract sources and run
$ python setup.py installDebian bookworm, bullseye, buster or Ubuntu lunar, jammy, focal packages can be found in the HDRI repository.
To install the debian packages, add the PGP repository key
$ sudo su
$ curl -s http://repos.pni-hdri.de/debian_repo.pub.gpg | gpg --no-default-keyring --keyring gnupg-ring:/etc/apt/trusted.gpg.d/debian-hdri-repo.gpg --import
$ chmod 644 /etc/apt/trusted.gpg.d/debian-hdri-repo.gpgand then download the corresponding source list
$ cd /etc/apt/sources.list.d
$ wget http://repos.pni-hdri.de/bookworm-pni-hdri.listTo install tango server
$ apt-get update
$ apt-get install nxswriteror
$ apt-get update
$ apt-get install nxswriter3for older python3 releases.
To install only the python3 package
$ apt-get update
$ apt-get install python3-nxswriterand for python2
$ apt-get update
$ apt-get install python-nxswriterif exists.
To install it from pip you can
$ python3 -m venv myvenv
$ . myvenv/bin/activate
$ pip install nxswriterMoreover it is also good to install
$ pip install pytango
$ pip install pymysqldb
$ pip install psycopg2-binary
$ pip install cx-oracleTo set up NeXus Writer Server run
$ nxsetup -x NXSDataWriterThe nxsetup command comes from the python-nxstools package.
In order to use Nexus Data Server one has to write a client code. Some simple client codes are in the nexdatas repository. In this section we add some comments related to the client code.
# To use the Tango Server we must import the tango module and
# create DeviceProxy for the server.
import tango
device = "p09/tdw/r228"
dpx = tango.DeviceProxy(device)
dpx.set_timeout_millis(10000)
dpx.Init()
# Here device corresponds to a name of our Nexus Data Server.
# The Init() method resets the state of the server.
dpx.FileName = "test.h5"
dpx.OpenFile()
# We set the name of the output HDF5 file and open it.
# Now we are ready to pass the XML settings describing a structure of
# the output file as well as defining a way of data storing.
# Examples of the XMLSettings can be found in the XMLExamples directory.
with open("test.xml", 'r') as fl:
xml = fl.read()
dpx.XMLSettings = xml
dpx.JSONRecord = '{"data": {"parameterA":0.2},
"decoders":{"DESY2D":"desydecoders.desy2Ddec.desy2d"},
"datasources":{
"MCLIENT":"sources.DataSources.LocalClientSource"}
}'
dpx.OpenEntry()
# We read our XML settings settings from a file and pass them to the server via
# the XMLSettings attribute. Then we open an entry group related to the XML
# configuration. Optionally, we can also set JSONRecord, i.e. an attribute
# which contains a global JSON string with data needed to store during opening
# the entry and also other stages of recording. If external decoder for
# DevEncoded data is need one can registred it passing its packages and
# class names in JSONRecord,
# e.g. "desy2d" class of "DESY2D" label in "desydecoders.desy2Ddec" package.
# Similarly making use of "datasources" records of the JSON string one can
# registred additional datasources. The OpenEntry method stores data defined
# in the XML string with strategy=INIT.
# The JSONRecord attribute can be changed during recording our data.
# After finalization of the configuration process we can start recording
# the main experiment data in a STEP mode.
dpx.Record('{"data": {"p09/counter/exp.01":0.1, "p09/counter/exp.02":1.1}}')
# Every time we call the Record method all nexus fields defined with
# strategy=STEP are extended by one record unit and the assigned to them data
# is stored. As the method argument we pass a local JSON string with the client
# data. To record the client data one can also use the global JSONRecord string.
# Contrary to the global JSON string the local one is only
# valid during one record step.
dpx.Record('{"data": {"emittance_x": 0.1}, "triggers":["trigger1", "trigger2"] }')
# If you denote in your XML configuration string some fields by additional
# trigger attributes you may ask the server to store your data only in specific
# record steps. This can be helpful if you want to store your data in
# asynchronous mode. To this end you define in the local JSON string a list of
# triggers which are used in the current record step.
dpx.JSONRecord = '{"data": {"parameterB":0.3}}'
dpx.CloseEntry()
# After scanning experiment data in 'STEP' mode we close the entry.
# To this end we call the CloseEntry method which also stores data defined
# with strategy=FINAL. Since our HDF5 file can contain many entries we can again
# open the entry and repeat our record procedure. If we define more than one entry
# in one XML setting string the defined entries are recorded parallel
# with the same steps.
# Finally, we can close our output file by
dpx.CloseFile()Additionally, one can use asynchronous versions of OpenEntry, Record, CloseEntry, i.e. OpenEntryAsynch, RecordAsynch, CloseEntryAsynch. In this case data is stored in a background thread and during this writing Tango Data Server has a state RUNNING.
In order to build the XML configurations in the easy way the authors of the server provide for this purpose a specialized GUI tool, Component Designer. The attached to the server XML examples was created by XMLFile class defined in XMLCreator/simpleXML.py.
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