First, as a note, I am not sure that what you refer to as "browse path" is an actual OPC UA browse path - that term has its specific meaning. Browse paths includes a starting node, and a sequence of browse names and references. See e.g.
opclabs.doc-that.com/files/onlinedocs/QuickOpc/Latest/User%2...wse%20Paths%20in%20OPC-UA.html . I think you are probabling referring to an OPC UA node ID with a string identifier that "looks" similar to some kind of browse path.
To the question: You can read an attribute of a node to see if it exists, and check for errors. You should read an attribute that *all* nodes have - I suggest, the UAAttributeId.NodeClass. If you get an exception, you need to test whether it represent a non-exist node, or some other kind of error. To do, you can use the following method:
static private bool IndicatesNonExistentNode(Exception exception)
{
switch (exception)
{
case UAStatusCodeException statusCodeException
when
// The syntax of the node id is not valid.
(statusCodeException.StatusCode.CodeBits == UACodeBits.BadNodeIdInvalid) ||
// The node id refers to a node that does not exist in the Server address space.
(statusCodeException.StatusCode.CodeBits == UACodeBits.BadNodeIdUnknown):
case UAServiceException serviceException
when (serviceException.ServiceResult == UACodeBits.BadNoMatch):
return true;
default:
return false;
}
}Note that if the read is done using one of the multiple-operand methods, the exception I am talking about is in the .Exception property of the ValueResult object returned. If you have used a single -operand method, it would throw, and the exception I am talking about will be the .InnerException of the UAException thrown.
We plan to expose a "helper method" to perform such checking in future QuickOPC version.
Best regards
