RegRep4 question: asynchronous query exceptions

[Pim van der Eijk <pvde@sonnenglanz.net>]

According to its charter, the ebCore TC is responsible for maintenance 
of ebXML specifications from previous ebXML TCs. The OASIS ebXML 
Registry TC that was closed by OASIS TC Administration on 29 October 
2019 and is no longer active. The last deliverable of that TC is the 
RegRep4 specification, 
https://docs.oasis-open.org/regrep/regrep-core/v4.0/os/.Â; In a customer 
project, we are looking at using the RegRep5 query manager interface 
with an asynchronous protocol (in fact ebMS3/AS4) and some questions 
are coming up. The ebCore TC mailing list can be used to discuss them 
and to help implementers.

A first question relates to how exceptions are returned by the 
server.ÂÂÂ There seem to be two options:

1)Â In the SOAP/WSDL binding provided by the OASIS standard, 
https://docs.oasis-open.org/regrep/regrep-core/v4.0/os/wsdl/1.1/regrep-server-interface.wsdl, 
the "fault" is linked to a "tns:msgRegistryException".

 <portType name="QueryManager">
ÂÂÂ <documentation>
ÂÂÂÂÂ The portType for QueryManager abstract interface.
ÂÂÂ </documentation>
ÂÂÂ <operation name="executeQuery">
ÂÂÂÂÂ <input message="tns:msgQueryRequest"/>
ÂÂÂÂÂ <output message="tns:msgQueryResponse"/>
ÂÂÂÂÂ <fault name="registryException" message="tns:msgRegistryException"/>
ÂÂÂ </operation>
 </portType>

 <message name="msgRegistryException">
ÂÂÂ <part element="rs:RegistryException" name="fault"/>
 </message>

The registry exception is defined in the RS schema, 
https://docs.oasis-open.org/regrep/regrep-core/v4.0/os/xsd/rs.xsd:

ÂÂÂ <complexType name="RegistryExceptionType">
ÂÂÂÂÂÂÂ <annotation>
ÂÂÂÂÂÂÂÂÂÂÂ <documentation>Base for all registry exceptions. Based upon 
SOAPFault: http://www.w3schools.com/soap/soap_fault.asp</documentation>
ÂÂÂÂÂÂÂ </annotation>
ÂÂÂÂÂÂÂ <complexContent>
ÂÂÂÂÂÂÂÂÂ <extension base="rim:ExtensibleObjectType">
ÂÂÂÂÂÂÂÂÂÂÂ <attribute name="code" type="string" use="optional"/>
ÂÂÂÂÂÂÂÂÂÂÂ <attribute name="detail" type="string" use="optional"/>
ÂÂÂÂÂÂÂÂÂÂÂ <attribute name="message" type="string"/>
ÂÂÂÂÂÂÂÂÂÂÂ <attribute name="severity" type="rim:objectReferenceType" 
default="urn:oasis:names:tc:ebxml-regrep:ErrorSeverityType:Error"/>
ÂÂÂÂÂÂÂÂÂ </extension>
ÂÂÂÂÂÂÂ </complexContent>
ÂÂÂ </complexType>
ÂÂÂ <element name="RegistryException" type="tns:RegistryExceptionType"/>

A problem with the RegistryExceptionType is that it does not have a 
"requestId" attribute, so there is no correlation of the exception to 
the request that it relates to. Â This is not an issue for SOAP/WSDL 
with an HTTP binding where the fault is returned synchronously, as it 
will be returned on the backchannel that is associated with a specific 
request. Â But it is problematic for the customer project as there all 
responses are asynchronous, and this type of application responses are 
not handled using SOAP faults.

2)Â A second option would be to wrap the exception in a regular ebRS 
response. This is from 
https://docs.oasis-open.org/regrep/regrep-core/v4.0/os/xsd/rs.xsd:

ÂÂÂ <complexType name="RegistryResponseType">
ÂÂÂÂÂÂÂ <annotation>
ÂÂÂÂÂÂÂÂÂÂÂ <documentation xml:lang="en">Base type for all ebXML 
Registry responses</documentation>
ÂÂÂÂÂÂÂ </annotation>
ÂÂÂÂÂÂÂ <complexContent>
ÂÂÂÂÂÂÂÂÂ <extension base="rim:ExtensibleObjectType">
ÂÂÂÂÂÂÂÂÂÂÂ <sequence>
ÂÂÂÂÂÂÂÂÂÂÂÂÂ <element name="Exception" 
type="tns:RegistryExceptionType" minOccurs="0" maxOccurs="unbounded"/>
ÂÂÂÂÂÂÂÂÂÂÂÂÂ <element ref="rim:RegistryObjectList" minOccurs="0" 
maxOccurs="1"/>
ÂÂÂÂÂÂÂÂÂÂÂÂÂ <element ref="rim:ObjectRefList" minOccurs="0" 
maxOccurs="1"/>
ÂÂÂÂÂÂÂÂÂÂÂ </sequence>
ÂÂÂÂÂÂÂÂÂÂÂ <attribute name="status" type="rim:objectReferenceType" 
use="required"/>
ÂÂÂÂÂÂÂÂÂÂÂ <!-- id is the request if for the request for which this is 
a response -->
ÂÂÂÂÂÂÂÂÂÂÂ <attribute name="requestId" type="anyURI" use="optional"/>
ÂÂÂÂÂÂÂÂÂ </extension>
ÂÂÂÂÂÂÂ </complexContent>
ÂÂÂ </complexType>
ÂÂÂ <element name="RegistryResponse" type="tns:RegistryResponseType"/>

This schema definition allows exceptions to be returned in a 
RegistryResponse that contains an Exception element.

<?xml version="1.0" encoding="UTF-8"?>
<query:QueryResponse requestId="c4369c4d-740e-4b64-80f0-7b209a66d629"
status="urn:oasis:names:tc:ebxml-regrep:ResponseStatusType:Failure"
ÂÂÂ xmlns:xlink="http://www.w3.org/1999/xlink"; 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
ÂÂÂ xmlns:rim="urn:oasis:names:tc:ebxml-regrep:xsd:rim:4.0"
ÂÂÂ xmlns:query="urn:oasis:names:tc:ebxml-regrep:xsd:query:4.0"
ÂÂÂ xmlns:rs="urn:oasis:names:tc:ebxml-regrep:xsd:rs:4.0"
xsi:schemaLocation="urn:oasis:names:tc:ebxml-regrep:xsd:query:4.0
http://docs.oasis-open.org/regrep/regrep-core/v4.0/os/xsd/query.xsd";>
ÂÂ ÂÂ <query:Exception xsi:type="rs:AuthorizationExceptionType"
severity="urn:oasis:names:tc:ebxml-regrep:ErrorSeverityType:Error"
ÂÂÂÂÂ message="Not Authorized"Â detail="Party xxx_9876543210 is not 
authorized to request XXX in context YYY"/>
</query:QueryResponse>

As the QueryResponse has a correlation attribute "requestId", the 
exception can be correlated to the request it relates to.

Problem is that section 1.2.2.2 of 
https://docs.oasis-open.org/regrep/regrep-core/v4.0/os/regrep-core-rs-v4.0-os.pdf 
seems to require use of "fault" messages for failures, and disallows 
values with a status Failure. But this requirement seems to only apply 
to SOAP/WSDL (other protocols do not have a concept of synchronous 
"fault" messages), and that 
urn:oasis:names:tc:ebxml-regrep:ResponseStatusType:Failure is a valid 
option for an asynchronous response protocol.

Looking forward to any comments.

Kind Regards,

Pim