SOAP Fault Detail — Understanding Error Reporting in SOAP Messages

SOAP_FAULT_CODES = {
    '1.1': {
        'VersionMismatch': 'soap:VersionMismatch',
        'MustUnderstand': 'soap:MustUnderstand',
        'Client': 'soap:Client',
        'Server': 'soap:Server'
    },
    '1.2': {
        'VersionMismatch': 'http://www.w3.org/2003/05/soap-envelope/VersionMismatch',
        'MustUnderstand': 'http://www.w3.org/2003/05/soap-envelope/MustUnderstand',
        'Sender': 'http://www.w3.org/2003/05/soap-envelope/Sender',
        'Receiver': 'http://www.w3.org/2003/05/soap-envelope/Receiver'
    }
}

def create_soap_fault(version, code, message, actor=None, detail=None):
    """Create a SOAP Fault response"""
    ns = 'http://schemas.xmlsoap.org/soap/envelope/' if version == '1.1' else 'http://www.w3.org/2003/05/soap-envelope'
    fault_code = SOAP_FAULT_CODES[version].get(code, f'soap:{code}')

    fault = f'<soap:Fault xmlns:soap="{ns}">\n'

    if version == '1.1':
        fault += f'  <faultcode>{fault_code}</faultcode>\n'
        fault += f'  <faultstring>{message}</faultstring>\n'
        if actor:
            fault += f'  <faultactor>{actor}</faultactor>\n'
    else:
        fault += f'  <soap:Code>\n    <soap:Value>{fault_code}</soap:Value>\n  </soap:Code>\n'
        fault += f'  <soap:Reason>\n    <soap:Text xml:lang="en">{message}</soap:Text>\n  </soap:Reason>\n'
        if actor:
            fault += f'  <soap:Node>{actor}</soap:Node>\n'

    if detail:
        fault += f'  <detail>\n{detail}\n  </detail>\n'

    fault += '</soap:Fault>'
    return fault

import xml.etree.ElementTree as ET

def parse_soap_fault(xml_string):
    """Parse a SOAP Fault into a structured error"""
    root = ET.fromstring(xml_string)
    version = '1.2' if 'http://www.w3.org/2003/05/soap-envelope' in xml_string else '1.1'
    ns = {'s': 'http://schemas.xmlsoap.org/soap/envelope/' if version == '1.1' else 'http://www.w3.org/2003/05/soap-envelope'}

    fault_info = {}

    if version == '1.1':
        faultcode = root.find('.//s:faultcode', ns)
        faultstring = root.find('.//s:faultstring', ns)
        faultactor = root.find('.//s:faultactor', ns)
        detail = root.find('.//s:detail', ns)

        fault_info = {
            'code': faultcode.text if faultcode is not None else None,
            'message': faultstring.text if faultstring is not None else None,
            'actor': faultactor.text if faultactor is not None else None,
            'detail': ET.tostring(detail, encoding='unicode') if detail is not None else None
        }
    else:
        code = root.find('.//s:Code/s:Value', ns)
        reason = root.find('.//s:Reason/s:Text', ns)
        node = root.find('.//s:Node', ns)
        detail = root.find('.//s:Detail', ns)

        fault_info = {
            'code': code.text if code is not None else None,
            'message': reason.text if reason is not None else None,
            'actor': node.text if node is not None else None,
            'detail': ET.tostring(detail, encoding='unicode') if detail is not None else None
        }

    return fault_info

def create_business_fault(error_code, error_message, details):
    """Create an application-specific SOAP Fault"""
    detail_xml = f'''
    <ns:ErrorDetails>
      <ns:ErrorCode>{error_code}</ns:ErrorCode>
      <ns:ErrorMessage>{error_message}</ns:ErrorMessage>
      <ns:Timestamp>{datetime.utcnow().isoformat()}Z</ns:Timestamp>
    </ns:ErrorDetails>
    '''
    return create_soap_fault('1.1', 'Server', 'Application error occurred', detail=detail_xml)

# Example: validation fault
def create_validation_fault(validation_errors):
    errors_xml = '\n'.join([
        f'    <ns:ValidationError>\n'
        f'      <ns:Field>{err["field"]}</ns:Field>\n'
        f'      <ns:Message>{err["message"]}</ns:Message>\n'
        f'    </ns:ValidationError>'
        for err in validation_errors
    ])
    return create_business_fault('VALIDATION_ERROR', 'Request validation failed', errors_xml)