How to use CXF 3.x implementation of JAX-RS 2.0 (REST) with Weblogic 12c

When I had to deploy a webapp with REST web services based on CXF 3.x on Weblogic 12c server, my problems started. With default configuration, Weblogic wants to use its internal implementation (JAX-RS 2.0 and serialization) to deploy the REST web services (Error 500):

java.lang.LinkageError: ClassCastException: attempting to castjar:file:/opt/weblogic/oracle_common/modules/javax.ws.rs.javax.ws.rs-api.jar!/javax/ws/rs/ext/RuntimeDelegate.class to jar:file:/opt/weblogic/oracle_common/modules/javax.ws.rs.javax.ws.rs-api.jar!/javax/ws/rs/ext/RuntimeDelegate.class

at javax.ws.rs.ext.RuntimeDelegate.findDelegate(RuntimeDelegate.java:146)

at javax.ws.rs.ext.RuntimeDelegate.getInstance(RuntimeDelegate.java:120)

at javax.ws.rs.core.Response$ResponseBuilder.newInstance(Response.java:848)

at javax.ws.rs.core.Response.status(Response.java:590)

at javax.ws.rs.core.Response.status(Response.java:601)

After many researches and the reading of Oracle posts (I even tried to open a SR at Oracle but it wasn’t really helpful this time), I manage to find a working configuration. This configuration sets Weblogic not to choose its own implementations for web services deployment and resources serialization.

To let CXF works (and Jackson here for the serialization side), you have to change these configuration files:

../webapp/WEB-INF/weblogic.xml :

<weblogic-web-app  xmlns="http://xmlns.oracle.com/weblogic/weblogic-web-app"
                   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                   xsi:schemaLocation="http://xmlns.oracle.com/weblogic/weblogic-web-app
                                       http://xmlns.oracle.com/weblogic/weblogic-web-app/1.8/weblogic-web-app.xsd">
<!-- ... -->
<container-descriptor>
	<prefer-application-packages>
		<package-name>javax.ws.rs.*</package-name>
		<package-name>com.fasterxml.jackson.*</package-name> <!-- Your root serialization implementation package -->
	</prefer-application-packages>
	<!-- ... -->
</container-descriptor>

../META-INF/weblogic-application.xml

<wls:weblogic-application  xmlns:wls="http://xmlns.oracle.com/weblogic/weblogic-application"
                           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                           xsi:schemaLocation="http://xmlns.oracle.com/weblogic/weblogic-application
                                               http://xmlns.oracle.com/weblogic/weblogic-application/1.8/weblogic-application.xsd">

    <wls:prefer-application-packages>
      <wls:package-name>javax.ws.rs.*</wls:package-name>
      <wls:package-name>com.fasterxml.jackson.*</wls:package-name>
      <wls:package-name>weblogic.jaxrs.api.client.*</wls:package-name>
      <wls:package-name>weblogic.jaxrs.internal.api.*</wls:package-name>
      <wls:package-name>weblogic.jaxrs.dispatch.*</wls:package-name>
      <wls:package-name>weblogic.jaxrs.monitoring.util.*</wls:package-name>
    </wls:prefer-application-packages>

I hope this can help some REST web services developers with CXF 3 who have to deal with Weblogic 12c :)

Tchou !