Write blog post to demonstrate OPC-UA adapter

[bossenti]

Body

Within the last time we have spend a lot of work in our OPC-UA adpater, so this one is now really mature.
So, let's take some time to celebrate and write a blogpost that demonstrates the functionality and all features of this adapter.

The blog post should contain:

• an introduction to OPC-UA
  - what is it?
  - for which purpose is it used?
• show step by step how to connect to an OPC-UA source with streampipes
• demonstrate how easy it is to extract value from the data

Our blog posts are part of our website repository: https://github.com/apache/streampipes-website

Mentoring

As this issue is marked as good first issue: one of @dominikriemer, @tenthe, or, @bossenti are happy to provide help for getting started, just tag (one of) them if you want to start working on this issue and need some help.
This issue is ideal for people that are interested in getting started with StreamPipes and like to write technical articles.

StreamPipes Committer

I acknowledge that I am a maintainer/committer of the Apache StreamPipes project.

[Disha677]

@bossenti Can you please assign this task to me?

[bossenti]

@Disha677 welcome to StreamPipes 🎉

We are already looking forward to sour blogpost.
Please feel free to reach out if you need any assistant, hints, or you want to discuss/adapt the actual content of the blogpost 🙂

[niuniudeadams]

@bossenti Hi bossenti,
Is this issue still available? I can work on it.

[bossenti]

Hi @niuniudeadams,

welcome to StreamPipes 👋🏼
Glad you are interested in working on this blog post.

The topic is available. Would you want to start working on it right away?
The reason I ask is that we are currently revising our OPC-UA support (see #1650).
So it would be best if the blog post promoted the new version of our adapter and sink first. This might take some more time.
But you could at least start with the part about OPC-UA in general if you want to.

Please let me know if this is still of interest to you 🙂 .

[niuniudeadams]

Hi @bossenti ,
I am still interested and which part of code should I read to know OPC-UA?

[bossenti]

amazing!

For the first part of the article, some general sources like books or the internet might be a good starting point:

• an introduction to OPC-UA
  - what is it?
  - for which purpose is it used?

If you already want to dig into the codebase, all OPC-UA related code can be found here.
But please be aware that is subject of substantial changes in the upcoming weeks 🙂

[niuniudeadams]

Hi bossenti,
I start learning OPC-UA currently. If I have some questions, I would ask you.

[niuniudeadams]

Hello, bossenti.
I've already learned what OPC-UA is and how to use it. I'm currently reading the code.

[nicoleu23]

Hi @bossenti ,
I just discovered the Apache Streampipes, I am liking it and using it for a project but I have trouble with the OPC-UA (Read) adapter of the latest version.

I succeed at creating the OPC-UA adapter and pipeline but not the two dashboards. After creating my widget in the dashboard explorer I get "Found no data in selected time range" yet I have numerous message in the #Messages column of the connect icon, meaning I am well connected to the machine but cannot visualize anything. I've tried different things even watched tutorials but I am still stuck.

This only happens when I am using the OPC-UA adapter and not the others.

I would be extremely grateful if anyone can help with this.

Thank you.

[tenthe]

Hi @nicoleu23,
thank you for contacting us.

Do I understand your problem correctly, you were able to connect to OPC-UA and start an adapter? And the adapter displayed data in the live preview?
However, the data cannot be visualized in the Data Explorer?

Can you check if the data explorer works with other data like the machine data simulator?

Cheers,
Philipp

[nicoleu23]

Thank you for reaching back.

It is also not visible in the live preview. I did check and it works perfectly with the machine data simulator. I don't know if there is a step that I am leaving behind for the OPC UA.

Thank you again.

Nicole

[tenthe]

Ok.

Can you provide a little more information about the OPC UA nodes you are trying to connect?
How many nodes are you trying to connect? What data type do they have?
Is an event schema displayed in the "Configure fields" confifuration step?

Which adapter type have you selected? (Pull mode or Subscription mode)

Maybe you can try connecting just one node.

To test if it works as expected you can watch the live preview after the start.
Live data must be displayed there.

Cheers,
Philipp

[nicoleu23]

I have tried connecting one node and it was also not working.

The different data types I have are double, integer, and float for now. "Schema ok" is displayed in green in the configure fields.

I have selected Pull mode as adapter type.

Also, in the Configuration>Data Lake, in the #Events column the value is "0". I find it strange.

Thanks,
Nicole

[tenthe]

Hmm, that's very strange.
Can you read values from the OPC UA server with other tools?

Is it possible for you to provide the full configuration you used?

[nicoleu23]

Hello @tenthe ,

I was finally able to do it with a new program, trying to figure out why it is not working for some. Thank you again for your help.

I do have another issue though, anytime I modify an existing adapter (OPCUA) for example it's Pull interval Timespan. I cannot view the new dashboard or data explorer.

I get this error "java.lang.ClassCastException" in the data lake's logs, which I fail to understand and don't how to solve. This is the same error I was getting before on my first issue as well.

Thank you,

Nicole

[tenthe]

Hi Nicole,

I just tested it locally, and there seems to be a problem with the Add timestamp rule when editing an adapter. Please try removing the timestamp field in the Configure fields step and then adding it back.

I have opened issue #2458 to fix this issue.

Please let me know if the quick fix resolves the issue for you or if you have any other issues.

Cheers,
Philipp

[nicoleu23]

Hello Philipp,

Thank you for fixing it, I just did what you mentioned above and the adapter is now perfectly restarting.

Is it possible to have further details on the error "java.lang.ClassCastException", please? I am asking this because it is the same error I was getting on the first issue of one week ago, when I couldn't visualize anything in the Dashboard and Data View for already existing programs. It is now working for a brand new program yet I am using the same configurations as last week's (existing programs).

I can read the OPC UA server's values with other tools of already existing programs but Streampipes would really be a perfect match for the project I am working on.

Thank you again,

Nicole

[tenthe]

Hi Nicole,

is there a way to reliably replicate the error?
As of now, I haven't encountered this particular issue.
However, if I'm able to reproduce it, I can investigate further.

It would also be helpful if you could check the logs and provide the error message if one is shown.

Cheers,
Philipp

[nicoleu23]

Hi Philipp,

I will do it again and see if the error appears.

Thank you for your help!

Nicole