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12:24, EET
November 12, 2018
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Hi there,
I would like to check if I have write permissions to some node on an OPC UA server.
I first found the UserWriteMask which turned out not to be the thing I was searching for.
Then I found the writeValue() methods in the UaClient. The Javadoc lists possible return codes including Bad_WriteNotSupported, Bad_NotWritable, and Bad_UserAccessDenied, which would tell me if a write operation suceeded or not.
However, I do not change values on the OPC UA server in order to check my write permissions.
So my question is:
When I have a UaNoed at the Prosys client, how do I check if I have write permissions without modifying the node?
Thank you!
14:11, EET
November 28, 2018
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Hi,
When you want to check the write permissions before writing to a Node, you can check if its UserAccessLevel Attribute includes value CurrentWrite. With a UaNode, this can be done, for example, by first converting it to a UaVariable as shown below:
if ((UaVariable)node).getUserAccessLevel().contains(AccessLevel.CurrentWrite) { /* your code here */ }
15:48, EET
November 12, 2018
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Thank you, this approach worked! Just to be complete, I will post my code snippet below:
if (node instanceof UaVariable) {
Set<AccessLevel> accessLevel = ((UaVariable) node).getAccessLevel();
accessLevel.contains(AccessLevel.CurrentRead); // Get read permission
accessLevel.contains(AccessLevel.CurrentWrite); // Get write permission
}
Again, thank you for your fast reply.
14:23, EET
November 12, 2018
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Hi Teppo,
I experienced a “permission denied” on read although the read permission discussed above returned true.
Do you have any suggestion how I could verify this in advance, before I get an error during my read operation?
Thank you.
at com.prosysopc.ua.client.UaClient.checkOperationResult(Unknown Source) ~[ProSysSDK-2.2.6-708.jar:2.2.6.708]
at com.prosysopc.ua.client.UaClient.readAttribute(Unknown Source) ~[ProSysSDK-2.2.6-708.jar:2.2.6.708]
What did I do? (1) accessLevel.contains(AccessLevel.CurrentRead) returned true, (2) I called uaClient.readValue(nodeId) and (3) got this error.
16:47, EET
November 28, 2018
Offline
Hello again,
In the above code, you’re using getAccessLevel that gives you Access Levels available for the Node in general. Try getUserAccessLevel, as in my earlier example, and you should get the correct response according to your User Access Level. Hope this works 🙂
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