Hi Tim,

If I understand you correctly, you want to define a DataType Name, which consists of two strings (FirstName and LastName). Then you want to define OuterType (either an ObjectType or VariableType) that has two components, Id and People. Once you’ve defined a custom DataType Name, you can simply create an array of them in a Node. So People would have as its value an array of Names.

However, using a custom DataType has the drawback of most UA clients not being able to understand it. Another option is to simply create FirstName and LastName as two Properties for Name. You can see an example in any UA server address space in ServerStatus node (Root -> Objects -> Server – ServerStatus), where the same information is available as a single value of ServerStatus and as Property nodes of it. While all UA clients can understand ServerStatusDataType, if they didn’t, they’d be able to access the same information in the Property nodes (CurrentTime, State, etc.) The exact same goes for the Property BuildInfo, and actually ServerStatusDataType contains also BuildInfo! So you have some choice on how to do this.

I hope this clarified DataTypes and Properties as two choices in exposing this information. Depending on your application and the expected clients the best practice may vary.

Yes, that is what could be considered as best practice since it allows quick and efficient access (via the custom DataType) as well as interoperability (via the Properties which all clients can understand). I wrote a blog post about using custom DataTypes, check it out if you haven’t already: http://www.prosysopc.com/blog/…..datatypes/

There are a few ways to model this:

1) OuterObject has HasComponent references to several Person nodes (so there is no single People node) and each of these Person nodes has as its DataType NameDataType (distinct from NameType, which is a VariableType with the two properties) and has the two Properties with DataType String. All the Person nodes have the same BrowseName, so TranslateBrowsePathsToNodeIds service calls involving these nodes will return all of them.

2) Have the DataType of People to be NameDataType and for People to contain an array of NameDataType. So once you have defined NameDataType, just create an array of those and place it as the value. FirstName and LastName then contains arrays of strings.

The spec is not completely clear about what the best practice in this kind of use case (with arrays) is. I would recommend approach 1), even though it involves more nodes.