thanks for the detailed answer. That helped a lot. I managed
to read the stored data from my test files. However, I noticed
that depending on the size of the used .mdf file, the call to
retrieve the `AoSession` from the `MDFConverter` takes a long
time. For a 170MB .mf4 file containing 184 CG Block's, the
following call:
took about 2m30s.
Is this expected? I guess it depends on the structure of the
MDF file. I used the example code you attached in your last
email. Should the file be read in a different way? Are there
any properties that should be set to speed it up?
Thanks in advance for your help.
Hi
David,
the
project org.eclipse.mdm.openatfx.mdf generates an ATFX
layer around a given MDF3 or MF4 file, which has to be
sorted (please see the MDF specification for details
regarding sorted MDF files).
Those
ATFX files are usually used for imports into so called
measurement systems which are driven by ODS servers.
Therefore the reading of the measured data may be done by
the ODS server, once the ATFX file has been imported.
However
I made a quick test with one of the MF4 test files
(bundled in this project) and was able to read the stored
channel data.
1.
Is
there an example/test case where the actual measurement
data is read from the file?
o
See
attached file (Example.java), I hope it gets you started
J
o
Within
the ATFX session you may find one or two measurements, the
second one is created one the fly, once needed:
i. „measurement“
will contain for each data group (DGBLOCK) with exactly
one channel group „CGBLOCK“ a so called SubMatrix.
A
ValueMatrix is spanned over the SubMatrix and is used to
read the stored measured data per colum „CNBLOCK“.
ii. „measurement_lookup“
will only be created for channels „CNBLOCK“s which have
lookup tables (value to value mappings, value range tot
ext mappings, etc.).
You
have to follow the same rules to access its data. The
given example should print the values for both
measurements. Try it with your test files…
o
The
library may create additional files next to your MF4 file
in the following cases:
i. Validation
bits of measured data are stored in a non ODS compliant
way, therefore the library exports them into an additional
binary file
ii. Channel
data with a rational conversion can not be represented in
an ODS compliant way, therefore they are fullly calculated
and stored in an additional binary file
2.
I'm
confused about the keys that are used to retrieve
ApplicationElements and InstanceElements from the
ApplicationStruture. Is there some resource describing
how to access the file and where the keys come from? I
tried to compare it to the keys shown by the
MDFValidator by VECTOR but they do not seem to match.
o
See
the comments in example. In short, the keys you see in the
MDFValidator are MDF specific and are reinterpreted and
stored in an ODS compliant way.
3.
I'm
unfamiliar with the ASAM OO-API and I couldn't find a
guide to the API. Also I couldn't find sources and
JavaDoc for the ods-5.3.0.jar to view this information
in Eclipse while looking at the tests.
o
The
full specification may be downloaded for ASAM members for
free:
https://www.asam.net/standards/detail/ods/older/
Additional
notes:
·
The
library may not support all possible channel
configurations you may have in your environment (it is not
a full implementation of the MDF specifications)
·
You
may want to write a JNI wrapper for this library
https://www.turbolab.de/mdf_libf.htm
·
You
may use the other project org.eclipse.mdm.mdfsorter to
sort unsorted MDF files
Regards
Viktor
Hi Angelika,
thanks for the quick answer.
Could you tell us which context you are
working?
We are developing a data analysis tool
called
KNIME Analytics Platform. It has a visual interface
where you can build so called workflows that model a data
pipeline with operations on the data modelled as nodes. Some
users from our community would be interested in a node to
read MDF files in our tool and do some analysis on the
measurement data. As our tool is written in Java, I was
investigating possible Java libraries that we could use to
read MDF and that we could integrate.
Are you interested in the openatfx.mdf
code or in the underlaying openatfx driver?
Actually, I'm not 100% sure. If I
understood correctly, openatfx.mdf provides functionality to
read MDF files using the openatfx driver? However, I was
having troubles reading the actual measurement data from the
a MF4 file. I cloned
this repository and had a look
at the test cases. Specifically I have the following
questions:
1) Is there an example/test case where the actual
measurement data is read from the file?
2) I'm confused about the keys that are used to retrieve
ApplicationElements and InstanceElements from the
ApplicationStruture. Is there some resource describing how
to access the file and where the keys come from? I tried to
compare it to the keys shown by the
MDFValidator by VECTOR but they do not seem to match.
3) I'm unfamiliar with the ASAM OO-API and I couldn't find
a guide to the API. Also I couldn't find sources and JavaDoc
for the ods-5.3.0.jar to view this information in Eclipse
while looking at the tests.
Thanks for your help,
David
Am 07.03.2019 um 09:39 schrieb Angelika
Wittek, openMDM(R):
Dear David,
yes this is the right place to ask questions about the
Eclipse mdmbl project. Currently we are busy, so an answer
will be delayed up to next week.
Are you interested in the openatfx.mdf code or in the
underlaying openatfx driver? That library is hosted on
sourgeforge by Christian:
https://sourceforge.net/projects/openatfx/
Could you tell us which context you are working? Our
project is associated with the Eclipse openMDM Working
Group and we are always interested about the use cases of
our users.
Thanks
Angelika
--
openMDM(R) EWG product manager
mail: awittek.openMDM@xxxxxxxxxxxxxxxxxx
phone: +49 1577 1900802
Am 06.03.19 um 10:21 schrieb David
Kolb:
Dear MDM|BL Development Team,
I'm a working student at the company KNIME
and I'm currently investigating Java libraries which
provide functionality to read MF4 files. We'd like to
include this functionality into our open source
software.
After some search, I stumbled upon:
https://git.eclipse.org/c/mdmbl/org.eclipse.mdm.openatfx.mdf.git/about/
which lead me to this mailing list in the included
NOTICE.txt of the Git repository. As the author of the
project is marked as Christian Rechner, AUDI AG (here), I was confused who
to contact regarding some questions about the usage of
the library. Specifically, I am having troubles reading
the actual numeric content of some MF4 files, finding
examples, and finding documentation about the ASAM
OO-API.
If this is not the right place to ask these questions,
could you maybe point me into the right direction?
Otherwise, I would be happy to elaborate on my questions
and very thankful about your support.
Kind regards,
David Kolb
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