[GitHub] [cxf] andymc12 commented on pull request #779: CXF-8516: Fixing jaxrs.spec.provider.jaxbcontext readWriteProviderTest

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andymc12 commented on pull request #779:
URL: https://github.com/apache/cxf/pull/779#issuecomment-827062423


   @reta based on my reading of the spec, I think the original behavior is correct. (I'll reference Jakarta REST 3.0 spec, since it is publicly available - but it should be the same as 2.1, only with different package spaces):
   
   For MBRs, the first thing checked should be the media type, followed by Java parameter type, then the `isReadable` method.
   https://jakarta.ee/specifications/restful-ws/3.0/jakarta-restful-ws-spec-3.0.html#message_body_reader
   
   For MBWs, the first thing checked should be the Java return type, then the media type, then the `isWritable` method.
   https://jakarta.ee/specifications/restful-ws/3.0/jakarta-restful-ws-spec-3.0.html#message_body_writer
   
   Ultimately though, I don't think the order of these operations matters so long as there ends up with a sorted list of providers that satisfy all three requirements (can convert to/from the same object type, compatible media type, and `isReadable` / `isWritable` method returns true).
   
   In Open Liberty, we made a few tweaks to this process that you might want to incorporate into your changes:
   (1) We changed the `compareClasses` method slightly so that sub-classes are handled correctly: 
   https://github.com/OpenLiberty/open-liberty/blob/eca9d0bebc1a380e4f78ad1e849735a28aa87754/dev/com.ibm.ws.jaxrs.2.0.common/src/org/apache/cxf/jaxrs/provider/ProviderFactory.java#L1456
   
   (2) We cache the sorted list of MediaTypes for the MBRs/MBWs to avoid looking them up and sorting them on each request, ex:
   https://github.com/OpenLiberty/open-liberty/blob/eca9d0bebc1a380e4f78ad1e849735a28aa87754/dev/com.ibm.ws.org.apache.cxf.cxf.rt.frontend.jaxrs.3.2/src/org/apache/cxf/jaxrs/provider/ProviderFactory.java#L1170
   
   Hope this helps!


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