OPC UA Binding Document Feedback w.r.t. contentType

[danielpeintner]

Two comments coming from node-wot discussions.

The OPC UA Binding specifies contentType as follows

If the default serialization of the OPC UA server is used, the contentType should be assigned with the value "application/octet-stream".

After discussing with @egekorkan and @relu91 we think we should not assign the content to "octet-stream" only. Does the statement above allow for the JSON variant also? I think it should/could mention it.

Second, we think we should prefix both types with opcua+

• application/opcua+octet-stream
• application/opcua+json

Doing so makes it clear that it is not any octet-stream but the one from OPC UA

@sebastiankb

[sebastiankb]

@randy-armstrong @barnstee

There seems to be no IANA registration for the OPC UA Content Type serialization. I could only find some information here:

https://reference.opcfoundation.org/Core/Part6/v104/docs/7.4.4

However, the HTTP header Content-Type has used application/octet-stream once and application/opcua+uabinary once.

[relu91]

I would support having a specific opcua content type. I want to add that the content-type field in the Thing Description should not be confused with the content type set in the HTTP request. Usually, those are practically the same, but the TD content-type refers to the final application payload, not the transport layer envelope.

[barnstee]

@randy-armstrong @barnstee

There seems to be no IANA registration for the OPC UA Content Type serialization. I could only find some information here:

https://reference.opcfoundation.org/Core/Part6/v104/docs/7.4.4

However, the HTTP header Content-Type has used application/octet-stream once and application/opcua+uabinary once.

@randy-armstrong, please register the ones used by OPC UA in IANA.