The EPCIS file transfer services are provided through a TemporaryFileTransferType, defined in OPC 10000-5. The transferred information is in the form of an EPCIS structured XML file, as described in Annex C. The EPCISStream object is used to push EPCIS Object Events (with various Business Steps in business process such as “urn:epcglobal:cbv:bizstep:commissioning”, “urn:epcglobal:cbv:bizstep:inspecting”, “urn:epcglobal:cbv:bizstep:packing”, “urn:epcglobal:cbv:bizstep:shipping”) and EPCIS Object Aggregation Events (with Business Steps as ‘urn:epcglobal:cbv:bizstep:packing’) to an OPC UA EventManager server.
The OPC UA TemporaryFileTransferType method GenerateFileForWrite is used to start the write file transaction. A successful call of this Method creates a temporary FileType Object and returns the NodeId of this Object and the file handle to access the Object. (From OPC 10000-5). The returned FileType object is not browsable in the AddressSpace and can only be accessed with the NodeId and FileHandle returned by the method in the same Session. The returned FileType Object is used to transfer the file stream between OPC UA Client and Server.
The EPCIS structured file is then transferred in blocks to the Event Manager server using the Write method. Once the transfer is complete the CloseAndCommit method is used to close the transfer, and the EventManager processes the transferred information.
The general use of the EPCISStream to transfer an EPCIS file is illustrated in Figure 13.
Figure 13 – EPCIS File Transfer Example
The GenerateFileForRead method of the EPCISStream object is not specified and shall always return an error from the EventManager.
The generateOptions is used for the GenerateFileForWrite to transfer arguments to the EventManager server that match the arguments used in the EventManager server’s event methods.
An EventManager Server shall specify OPENSCSEventStreamArgumentDataType as the concrete DataType of for the Argument Structure for the generateOptions argument in the instance of the GenerateFileForWrite method.