The OPC UA Complex Data extension does not require you to perform OPC operations any differently when complex data is involved. You use the same objects and methods as with the regular data. The only difference is in the data that is being passed to or from the component. When the OPC UA Complex Data extension is enabled (which is by default), complex data returned to you by the methods on the EasyUAClient Class is represented by instances of the UAGenericObject Class, and conversely, if you want to pass complex data to some method on the EasyUAClient Class, you need to prepare an instance of UAGenericObject Class. 

If the node being read, written or subscribed to represents an array (one- or multi-dimensional), the value passed to or from the component is then an array of UAGenericObject-s. Note that this is different from having a scalar node, and a UAGenericObject with generic data in that itself is an array (a sequence data). Both these options are possible (and sometimes a bit confusing).

The UAGenericObject class

The UAGenericObject Class is used to represent complex data on its way from the server or to the server. It has two basic pieces of information:

• The generic data itself, in the GenericData Property. This can be, for example, a primitive type (such as an integer), or a sequence (array), or a structured type with several fields of various types. The OPC UA Complex Data extension gives you methods to process generic data, and to create it. For more information, see Generic data and data types.
• An optional data type ID, in the DataTypeId Property. In most cases you do not need to be concerned about the data type ID. It is filled in when an instance of the UAGenericObject Class is returned from the server by the component. When you are sending generic data to the server through the component, you can usually leave this property unfilled, except in some situations where sub-types are involved. For more information, see Role of the data type ID.

Steps to use complex data

Here is what you need to do in order to work with OPC UA complex data.

• To read complex data information: Call one of the Read methods on the EasyUAClient Class as usual. When complex data is returned by the client, you will receive a value that is of type UAGenericObject Class, and you will process its contents. For more information, see OPC UA Complex Data reading.
• To subscribe to complex data information: Call one of the Subscribe methods on the EasyUAClient Class as usual. When complex data is returned by the client, a DataChangeNotification Event or EventNotification Event will be raised (or a corresponding callback will be made). The value in the event arguments will be of type UAGenericObject Class, and you will process its contents. For more information, see OPC UA Complex Data subscribing.
• To write a complex data information: Prepare an value of the UAGenericObject Class, and call one of the Write methods on the EasyUAClient Class as usual. For more information, see OPC UA Complex Data writing.

With the OPC UA Complex Data extension, it is also possible to call OPC UA methods that have complex data in their input arguments, or that return complex data in their output arguments. You will use a usual call to one of the Call methods on the EasyUAClient Class again.