Registering StAXElementLoader to the LoaderRegistry by QName

[Raymond Feng]

Hi,

As reported by JIRA issue Tuscany-437 
(http://issues.apache.org/jira/browse/TUSCANY-437), we should be able to handle 
SCDL using different XML styles illustrated as follows.

   <component name="HelloWorldServiceComponent"> 
        <!-- Style 1: using substitution group -->
         <!-- 
        <implementation.java class="helloworld.HelloWorldImpl"/> 
        --> 
        <!-- Style 2: using xsi:type -->
        <implementation xsi:type="JavaImplementation" 
class="helloworld.HelloWorldImpl"/> 
    </component> 

To address this issue, I would like to propose that we provide SPI in 
LoaderRegistry to register a StAX loader by either the QName of the XSD element 
or the type. Upon this, the runtime behavior can be:

1) First check if there is a loader in the registry under the QName of the 
element, if yes, then use it
2) If no, then try to check if there is an "xsi:type" attribute on the element, 
if yes, use the value of the xsi:type (QName) to look up the registry
3) If neither step 1 or 2 can find a corresponding loader, the loading process 
will fail.

Any other ideas?

Thanks,
Raymond