EPIC: Define a mapping of Addressspace infos to OPC UA PubSub

[DasbachVDMA]

Define the topic structure and the UA JSON structure for the MQTT broker.

Preliminary discussions:

• Maybe reuse the browsepathes
• The approach must be repeatable for each OPC UA CS

@Kantiran91 Please make a appointment for a workshop

[Kantiran91]

2024-04-17:
Target of the topic structure + encoding:
The nodes defined by a type definition (from a Companion Specification) are transmitted in MQTT.

Requirements for the topic structure

• Be able to react to dynamic changes in the address space (nodes are added / nodes are deleted)
• Resolve pro-mans references (NodeId as values)
• Hierarchy references must be mapped
• No-hierachy references should be mapped if necessary
• Provide TypeInformation
• Methods should already be considered
• Online detection (possibly as separate topics)
• Objects that can be empty.
• Events / alarms must be able to be mapped
• Coordinate the completeness of the run
• The encoding should be UA JSON
• Dimensioning for approx. 350 subscribers (machines + dashboard users)
• Custom DataType must be included

Idea: Own dataset for publisher

• Gateway version
• Error message
• Status

[Kantiran91]

todos:

• @Kantiran91 Read Part 14 and prepare a presentation
• Develop a draft for the topic structure
• Make a workshop for defining the structure (@wlkrm @Kantiran91 @mdornaus @karstenroethig )

[Kantiran91]

ideas for mapping the Hierarchy references must be mapped:

• in topic structure (fit not good in opc ua standard)
• BrowsePath as Property in MetaDataField
• Properties of DataSetWriterProperties

ideas for mapping references to KeyValuePair:
Key (QualifiedName): Browsename of the ReferenceType
Value(NodeId): NodeId of the TargetValue

[Kantiran91]

Here is a wiki article that contain all infos for this discussion:
https://github.com/umati/UA-CloudPublisher/wiki/Recommendations-for-Mapping-OPC-UA-Addessspace-information-in-OPC-UA-Pub-Sub

[Kantiran91]

@mdornaus @wlkrm @GoetzGoerisch @karstenroethig @ccvca
I have create an draft for the Pub/Sub Spec of the Dashboard.
Can you please review the document?

#54

[ccvca]

https://reference.opcfoundation.org/Core/Part3/v105/docs/5.2.4

There is also no rule, that BrowseNames must not contain any of the following characters: ./:

[Kantiran91]

https://reference.opcfoundation.org/Core/Part3/v105/docs/5.2.4

There is also no rule, that BrowseNames must not contain any of the following characters: ./:

Yes that why we use the BrowsPath as name which can be used for intentify.

If you flow the annex of Part 4 the character are not allowed:
https://reference.opcfoundation.org/Core/Part4/v105/docs/A

Do you suggest that we give a hint how to solve BrowsePath conflicts? e.g. allowing to add an iteration value?

[ccvca]

/ is allowed, ist just needs to be prefixed by a &, which will screw up MQTT as well.

<name>::= (<name-char> | '&' <reserved-char>) [<name>]
<reserved-char>::= '/' | '.' | '<' | '>' | ':' | '#' | '!' | '&' 
<name-char> ::= All valid characters for a String (see [OPC 10000-3](https://reference.opcfoundation.org/Core/Part3/v105/docs/)) excluding reserved-chars.

In the current version, this is solved by an URL-Encoding using an underscore instead of a '%'.