How to return SOAPFault from XMLAdapter?

I'm developing a SOAP based WebService (JAX-WS) and dates come with specific format "yyyymmdd". My WSDL defines the date as string but I would like to return a SOAP fault response when the expected format is not followed by the element value. I've defined an XMLAdapter for element and tried the following in unmarshall method:

public XMLGregorianCalendar unmarshal(String value) throws Exception {
    if (!checkCorrectFormat(value)){
        throw new RuntimeException();
    }

    return ParseHelper.getInstance().parseStrDateToXMLDate(value);
}

But the exception is lost and the WebService goes on without problem getting a null XMLGregorianCalendar value for the unmarshalled element. Perhaps this is not the right place to implement this format control... Any help would be appreciated.

Consider implementing this regex restriction in your xsd:

  <xsd:simpleType name="MySpecialDate">
    <xsd:restriction base="xsd:string">
      <xsd:pattern value="\d{4}\d{2}\d{2}"/>
      <xsd:whiteSpace value="collapse"/>
    </xsd:restriction>
  </xsd:simpleType>

\d{4}-\d{2}-\d{2} might not be quite as strict as you need to follow the rules of a gregorian calendar. For instance, 20121312 would not be a valid gregorian date because there is no 13th month in the gregorian calendar but it would still pass your regex restriction. But you can definitely create a regex that conform to the gregorian rules with a couple google searches.

And then, let JAXWS do the schema validation for you. see "To activate Service-side validation" on http://www.jroller.com/gmazza/entry/soap_xml_schema_validation

Also, if you have to do the ccyymmdd format you can't use xsd:date which, in my mind, would be preferable because Jaxb will create a java.util.Date for you as your property right from the start. You can still achieve this (generating a java.util.Date) with your custom ccyymmdd format but it is a little more work. You would probably use a jaxb custom binding. Something like this would go into your .jxb file and used with the xjc task:

<jxb:bindings node="//xs:simpleType[@name='MySpecialDate']">
  <jxb:javaType name="java.util.Date"
        parseMethod="com.company.DateConverter.parseMySpecialDate" 
        printMethod="com.wpsic.tricare.ws.converter.DateConverter.printMySpecialDate" />
</jxb:bindings>