Step 4: Call any web service operation with previously returned WS-Addressing 1.0 reference parameters

Before calling any web service operation, you must set the WS-Addressing 1.0 reference parameters returned by a session initiator function to identify the session to the server.

For example:
LET StatefulWSAddressingService_StatefulWSAddressingServicePortTypeEndpoint.
Address.Parameters.* = instance1.* 
# assign WS-Addressing 1.0 reference parameters dynamic array by reference
CALL MyFunction("Hello") RETURNING wsstatus,ret  
# Call web operation MyFunction of instance 1