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convertersystems / opc-ua-client

Visualize and control your enterprise using OPC Unified Architecture (OPC UA) and Visual Studio.
MIT License
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FindServersOnNetwork #175

Open ismiwo opened 3 years ago

ismiwo commented 3 years ago

I can't find a method to make use of the FindServersOnNetworkRequest. Shouldn't there be a method inside UaTcpDiscoveryService for this purpose?

quinmars commented 3 years ago

Good question! As I understand the specification, the FindServersOnNetwork request can be used to paginate the results. Hence one probably want to keep the channel open, so it can be reused in the follow up queries. On the other hand I like the simpliness of the current FindServersAsync and GetEndpointsAsync static methods, where you do not need to care about the creation and disposal of the channel. What do you think, should FindServersOnNetworkAsync be an instance method or should it be static?

awcullen commented 3 years ago

@ismiwo Which server do you use? The demo server from Unified automation does not seem to support this service request.

ismiwo commented 3 years ago

I'm using devices in our network that have built-in opc-ua-servers and I am using the server from this project: nauful/LibUA

Thank you for pointing to the specification. I found in 4.3.5 that a client can call this function on a LDS with MulticastExtension. I also found that servers don't have to register themselves (4.2.1).

I thought that UaExpert was able to discover servers automatically. But it was always only discovering my local server which doesn't seem to have LDS-ME capabilities. But UaExpert is also trying FindServersOnNetwork first when you want to add a server:

grafik

I realize now that I cannot rely on all the servers to be discovered automatically and that I will have to add other measures to discover them in our software (e.g. 4.3.1).

@quinmars I think the method should be static.

quinmars commented 3 years ago

An LDS-ME can be downloaded here: https://opcfoundation.github.io/UA-LDS/ - I haven't tried it yet.