1. Server has to be defined using a constructor which includes URI, Namespace, Portname,certificate details and security
2. A concept called Address space is primary in creating an OPC UA server.
a. Address Space contains information about nodes and its references also other data as well
b. Nodes are defined using namespace URI(or the index), Identifier() and identifier type
c. Nodes in address Space is the basic building blocks for saving and running a server
3. When the created server has to be picked up by any client including UA Expert it has to commmunicate using binary
4. Communication includes Hello, Acknowledgement, and closure
5. Separate Address Spaces are created in the OPC UA package that defines individual nodes(which contains methods, Variables and objects) and reference
nodes
6. The first index in the namespace URI is allocated to the OPC foundation where the Node id is as follows [ns = 0,s = identifier name]
7. Any user can further create their own namespace by registeredNamespace method and adding nodes and variables to it.
8. Base node class is available from which other nodes are defined. It has 8 basic types
Unspecified = 0
Object = 1
Variable = 2
Method = 4
ObjectType = 8
VariableType = 16
ReferenceType = 32
DataType = 64
View = 128
9. The base Node class helps a user create their own nformation model depending on the needs.
10. An information model is an upgrade to what one used to do when defining just a variable like temperature. In the OPC UA information model temperature
is just a node in the address space which can be a reference node to a say a boiler where the boiler is defined as a node as well. Now the Boiler is
part of a factory and it may act as a reference node to a furnace. This structure is what makes OPC UA unique.
11. Nodes are the basic information blocks of OPC UA
12. There are basic node types that are declared in the OPC UA
13. On top of this a basic models are built that include DataAccess, HistoricalDataAccess , Alarm and conditions and other inbuilt programs
14. All these are housed in Address Spaces which includes all the reference nodes
15. Companion specs are developed in collobration with the industry insiders based on the needs...for example Robotics industry would want to built
a machine using the OPC UA.
If we are to start developing an alternate to OPC UA, we'll have to start with configuring a server based on the industry needs and help the server
accept and send binary data to the clients that are trying to establish connection. Also create our own address space with all the node specifications
that include node id generation with multiple types and reference to those had to be integrated with the basic package.
