Accessing Properties with TDM Reader API

[ChrisStrykesAgain]

I'm trying to figure out if there's a mechanism for accessing file, group and channel properties in a TDMS file, that has been ingested by a DataFinder instance. For example, if I have set a "DUT" property on the file level, and need to be able to query it.

It looks like the TDM Reader HTTP API provides the needed data using the "metadata" functions, but I'm having trouble figuring out how to determine the file-id to pass in. Is this the correct mechanism to use? If so, are there any examples on how to use this API?

Worth noting, I see an NXG 4.0 version of this API listed, but don't see a LabVIEW 2019 version; is that correct?

[ChrisStrykesAgain]

It's slowly starting to click now that I've played with the TDM Reader API in NXG...

TDM Reader API only accesses files on the server that have been put there using the File API, not files indexed by a DataFinder. Furthermore, the 'filter' functionality in NXG seems to only act on metadata associated with the file as part of the upload process, not actual TDMS file/group/channel properties.

The only way to access files within a DataFinder is using the DataFinder API, which has a LabVIEW 2019 implementation. It allows you to extract specific property values and do all sorts of filtering based on them, which is essentially what I was looking for.

Is the above a fair assessment?

[Brad_Turpin · Accepted solution]

Hi ChrisStrykesAgain,

You are correct.  You need to use a DataFinder API to communicate with the DataFinder to issue queries or ask it about properties of queried items (Files/Groups/Channels).  All LabVIEW 2019 installers (and later) include the LabVIEW DataFinder Toolkit as an optional component.  Prior to LabVIEW 2019 you had to purchase this toolkit to get the installer.

You can also communicate with a DataFinder instance with built-in objects in a DIAdem VBScript or Analysis Server task, and the DataFinder instances will all respond to their web service API.  I'm coming at all of this from a DIAdem perspective, so I confess to not knowing what programming options are available in NXG or the web service options in SystemLink for ingested files.

Ask as you have further questions,

Brad Turpin

DIAdem Product Support Engineer

National Instruments

Brad

[ChrisStrykesAgain]

Brad,

I think my biggest question at this point is how to generate a report from the data accumulated by my DataFinder.

If I understand correctly, the analysis module has provisions for doing this, but I think it's overkill for what I'm trying to accomplish. I don't need any complex calculations or filtering, I just need to lookup a given DUT and display its test results graphically (with some minor calculations). It would also be a bonus if this could be done dynamically so that I don't have to store a permanent report for every test on a server somewhere.

My current thought is to build a WebVI that serves as a 'dashboard' of sorts and allows users to view test results, etc. BUT there isn't a DataFinder API for NXG. I'd like to dig in to the HTTP APIs deeper (presumably the Data Navigator Data Service), but I'm hitting a bit of a wall trying to decipher the documentation. I am also considering an indirect approach, running a 2019 web service strictly for the purpose of doing lookups and reporting back the required data, but that seems a bit kludgy.

So all that said, I guess my direction questions would be:

• Is there any additional documentation or resources on how to use the DataFinder HTTP API?
  • Edit: I found this, which helps a lot: http://localhost/systemlink-tdm-offline-doc/DataNavigatorDataService/DataNavigatorDataService.html 
• Should I pursue the 2019 Web Service approach?
• Is there a better option that I'm missing?

Also, on a tangential note, does the DataFinder database ingest the entire file, or does it just serve as a lookup? More to the point, do I need to keep the TDMS files on disk to ensure the data stays available, or can the files themselves be ephemeral?

[ChrisStrykesAgain]

Realized my original question was answered. Started a new thread to better track the questions re: DataFinder.