Information Modeling

If you, like me, has a background in object orientated programming, the UA information model should be easy. It is not. First you have to realize, that it is not exactly UML, but stereotyped UML. I was struggling a long time, because I tried to fit this model in to UML directly. The OPC UA Metamodel is in UML in UA Part 3. 

However, the model uses many things from object orientated programming, such as generalizations, etc. Although OPC UA offers a lot of tools and great potential for using information models, their use is not necessary. In simple applications, it is possible to construct an address space in the server and use it efficiently with only very rudimentary typing and modeling of the exposed information. This way, the data transport capabilities of UA are harnessed and data remains very close to what it was in classic OPC, that is, just pure data. However, by using information models, clients can perform sophisticated tasks by interpreting the semantics of the provided information, and not just the values. The main advantages and principles of information modeling in OPC UA are as follows according to Damm.

 

Example of a UA-model for an air condition controller:
 
 

All in all, the support for information models will enable new kinds of applications to be developed. This diagram might shed some light about how the OPC UA model is mapped to an object orientated class

 


If you want more in depth information you should read this book or/and have a look at this homepage.