Expanded NodeID vs. NodeID|OPC UA Standard|Forum|OPC Foundation

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Expanded NodeID vs. NodeID
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Frederick Loveless
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12/01/2017 - 13:00
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Looking for some recommendations. We have just encountered the first server we have ever seen that returns expanded NodeID's in a browse response. Since we have never seen a server that responded this we we never built support into the client to handle the expanded node ID. I am wondering if it is as simple as using "OPC_UA_Server_Softing_HMI.nsuri=OpcUaServer;s=Application.Pack_HMI.Pack_OPC.OPC_Mach_Homing" fir read requests and creating monitored items or if there is more work involved. I could not find specifics in the specificaitons.

I was also wondering if we read the namespace array from the server and go the index from the array for the above specified namespace should the server be able to handle us using the namespace index like "ns=5;s=Application.Pack_HMI.Pack_OPC.OPC_Mach_Homing"

 

Thanks for any input.

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Matthias Damm
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12/03/2017 - 07:26
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Servers return an expanded NodeId with ServerIndex > 0 if they have references to nodes in a remote server. This means that you will need to connect to this other remote server in order to access the referenced node.

For that reason, the expanded NodeId includes a ServerIndex. The server index points to the entry for the remote server in the ServerArray property of the local server (Server->ServerArray). The ServerArray contains the URI of the remote server. This URI can be used to discover the remote server.

The expanded NodeId with ServerIndex > 0 contains also a NamespaceUri. The NamespaceIndex of the node in the remote server must be read from the remote server using the NamespaceUri.

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