ExtensionObject

An ExtensionObject is a container for any complex data types which cannot be encoded as one of the other built-in data types. The ExtensionObject contains a complex value serialized as a sequence of bytes or as an XML element. It also contains an identifier which indicates what data it contains and how it is encoded.

Complex data types are represented in a Server address space as sub-types of the Structure data type. The encodings available for any given complex data type are represented as a DataTypeEncoding Object in the Server address space. The NodeId for the DataTypeEncoding Object is the identifier stored in the ExtensionObject. DataType describes how DataTypeEncoding node are related to other nodes the address space.

Server implementers should use namespace qualified numeric NodeIds for any DataTypeEncoding Objects they define. This will minimize the overhead introduced by packing complex data values into ExtensionObjects.