File transfer from Server to Client

[FIAV1]

Hi, I consider myself a regular customer now 😄
I saw there's a way to transfer an xml file from server to client, but is there a way to transfer any file from server to client?
Is this considered possible in an OPC UA environment?
I could help developing such a feature if still not present.
Thanks in advance! 💪

[swamper123]

I think there is a "FileType" in the OPC UA spec (part 5), but I think we haven't got a feature for that so far, have we? @oroulet

[FIAV1]

UPDATE
I found a workaround, i.e. open a file, read it in binary mode and send it in bytes. 🎉
Question for you guys: is this cool, or could it have performance issue with large files? Is there any better practice?
Thanks 🤓

[swamper123]

Question for you guys: is this cool, or could it have performance issue with large files?

Well I would say try it with a large file and do normal other OPC UA stuff concurrent. :^)
I guess it may cause trouble in the end, depending how you send it. Because if you send some GB data in a way, that the whole Eventloop has to wait until transfer is ready, it wouldn'''t be cool.

But what would maybe cool is a possibility to make a "standard" file objekt which contains the "standard" functions.

[FIAV1]

I guess it may cause trouble in the end, depending how you send it. Because if you send some GB data in a way, that the whole Eventloop has to wait until transfer is ready, it wouldn'''t be cool.

Ok, this is what i wanted to know, thanks 👍

But what would maybe cool is a possibility to make a "standard" file objekt which contains the "standard" functions.

You mean locally, or a new functionality to add to the core?

[swamper123]

You mean locally, or a new functionality to add to the core?

I saw this video and thought about doing such a thing as core function. It is a video of a company, but it seems to be an in general OPC UA thing.

[FIAV1]

Ok, I watched the video.

It is a video of a company, but it seems to be an in general OPC UA thing.

I think it's like you say, so the next question is: both client and server can send a file to each other, or is the communication unidirectional server->client?

[swamper123]

Well a Server serves what a Client requests, so I would guess it can be possible to send it bidirectional. Problem is, I haven't got the specs (and perhaps for another couple of days *sigh*) but will make a proper answer when I got them.

[FIAV1]

Ok then, I'll wait for updates 👍

[swamper123]

It was a long time ago, sry @FIAV1 , but finally I got them...but got also noticed, that you can download them for free on the foundation website, when you create a free account. 🤦 Haven't known that.
On the fly I found Annex C in part 5 (Information Model) which is about File Transfer, but I haven't read it all the way yet. Stay tuned. :D

[FIAV1]

Hi @swamper123, absolutely no problems, just this morning I thought about this project, I think this is a kind of sign 🤣
Anyways, I hope to hear you again soon, I'll stay tuned for sure, thanks a lot 💪

[swamper123]

Hmmm ... I am a bit confused about that stuff.
So yes, it seems like File Transfer is possible. You need open/close methods and read/write methods. Depending where the position of the file handler is, you can read/receive the raw bytes.

So back to your question, yes it is possible, just the implementation will be tricky (or a problem of the opc ua client).

I would recommened you to read this where you will find the necessarry methods, vars etc. which would be needed to be implemented.
Have a look in the repo, some stuff like:

opcua-asyncio/asyncua/ua/uaprotocol_auto.py

Line 27 in 3353bc8

class OpenFileMode(IntEnum):

Already exist and wait for you to use them. ;)

[jadamroth]

I created an example in issue #371 if it helps anyone

[oroulet]

This is now supported . See example. https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples/client-file.py