Good morning,

I have to convert my Java SOAP web services into OPC UA methods.

Use case 1:
Java method:
public void insertMaterial (String Code, Double Density);

Return:
– Return ok (the material has been added in the system)
– Return error due to:
Code is null
Code is already present in the system
Density is null

Use case 2:
Java method:
public List listMaterial();

Return:
– Return the list of materials
– Return error (server error)

I thought of creating a new structure:
ReturnType definition:
Returncode – 0:Uint32 (0 = OK, 1 = Error)
ReturnDescription – 0:String (additional informations / error description)

And eventually returns multiple output arguments (OPC UA standard allows you to return multiple results):

Use case 1:
Java Method:
public void insertMaterial (String Code, Double Density);

OPC UA output arguments:
– Arguments 0: ReturnType

Use case 2:
Java Method:
public List listMaterial();

OPC UA output arguments:
– Arguments 0: Returnype
– Arguments 1: Materials (xml string)

Is there a best practice to manage methods output arguments?

The EUROMAP 86 standard (https://www.euromap.org/euromap86) defines:
3.2.6 Resultcode
The Resultcode Gives Information About Each In-Parameter of a Method and Is Given by the Mss. It´s Formatted in a binary code:
– 0: ok
– 1: nok
3.2.7 Resultttext
The Resultttext

…

Example for a Resultcode with 2 materialids:
MSB -> 001010 msscomponentsids [0] = 7; Is Nok (E.G. Materialid is not listed)
0 -> msscomponentsids [1] = 2; is ok
1 -> msscomponentspercentage [0] = 110; Is Nok (E.G. Perntage> 100%)
0 -> msscomponentspercentage [1] = 25; is ok
MSB 0 -> Recipeid is ok

But this solution does not convince me. I would prefer to work with the structures and not with the binary encoded variables.

Best regards,
Francesco