17:29, EET
February 26, 2020
Hi,
we are successfully using the SDK to implement a client / server based product. The SDK meets our requirements, thanks for that !
Now, we would like to implement a software that (eventually, based on some application specific criteria) forwards UA requests from the client to a server using another server as a gateway, such as:
CLIENT – SERVER#A – SERVER#B – SERVER#C
Is the SDK appropriate for that ? If so, at which layer would you suggest we implement the feature ? We can modify the stack if needed …
Thanks for your help,
Cheers,
17:48, EET
April 3, 2012
Hi,
In theory, yes. In practice, buy https://www.prosysopc.com/products/opc-ua-gateway/.
Anyway while it can be made (we have done something related with our https://www.prosysopc.com/products/opc-ua-historian/), it is … let’s just say ‘very complicated’ and outside of any normal tech support we would give in the context of the SDK. But you can look at the MyBigNodeManager in the SampleConsoleServer, think that as “Server A” and delegate calls providing data to UaClient connected to “Server B”. Depending what you need it might be enough or not. But where at all possible, we would recommend just using UaGateway instead as that is designed and “battle-tested” on the field for those kinds of purposes.
10:03, EET
February 26, 2020
11:45, EET
February 26, 2020
And for your information, we cannot use UA Gateway for (at least) those 2 reasons:
we use Linux,
we do not want to have a secondary service to administrate, so we wish to have the “Gateway” service located inside the server itself …
Seems difficult to achieve actually, but we will give it a try.
Cheers,
16:51, EET
December 21, 2011
You can still take a look at the Prosys OPC UA Historian, which is, in fact, this kind of an aggregation server (or gateway) and available on Linux as well. The historian capability comes on top, but the real challenge was to do the aggregation. The trickiest part is the aggregation of namespaces, which you will have to do. If you are mapping several servers behind the gateway, you will have to merge the namespaces of all underlying servers to the NamespaceArray of the gateway. That means also that you cannot pass the incoming calls directly to the underlying servers, because you will have to convert all NodeIds and QualifiedNames respectively.
12:04, EET
February 26, 2020
Thanks a lot for your answer.
The issues are the ones you say. But I am trying to do it by modifying nodeIds directly … will see where it leads. We need both calls and events to be forwarded …
Another question: would you be interested by developping this feature for us ? If so, can we discuss that by email ?
Cheers
14:57, EET
April 3, 2012
Good Luck with the implementation 🙂 (But if you encounter any issues, let us know still, since there is of course always room for improvements with the SDK).
For the “us developing this for you” matter, I cannot answer that myself, but I would say either way it is best if you contact sales@prosysopc.com
P.S.
You will need to take into account NamespaceArray, ServerArray and anything that can have a Namespace or Server index. This means at least _anything_ that can have a NodeId, ExpandedNodeId or QualifiedName (since it has the namespaceindex as well) needs to be modified. And meaning like any possible Structure etc. that might use those types as their fields etc.
Best is if you can just use the NamespaceUris and ServerUris instead of indexes, but of course you will need to convert them back to indexes as some point.
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