7.3 Changing the Default Interceptor

The default interceptor can be changed by using the setMBeanServerInterceptor method of the JdmkMBeanServer interface. The JdmkMBeanServer interface provides methods for getting and setting the default MBeanServerInterceptor used for request treatment.

By default, the MBeanServer implementation returned by the MBeanServerFactory is not a JdmkMBeanServer, and does not support MBeanServerInterceptors. To use interceptor you have to set the javax.management.builder.initial System property to com.sun.jdmk.JdmkMBeanServerBuilder before obtaining an MBean server from the MBeanServerFactory. How to set this system property is shown in Step 2.

Particular care must be taken when replacing the default MBean server interceptor with a user interceptor. The MBean server implemented in the Java DMK 5.1 passes requests to its default interceptor without checking the result returned, or the exceptions thrown by the interceptor.

Consequently, user interceptors, which implement most of the methods defined in the MBeanServer interface, must behave as specified for the corresponding MBeanServer methods in the JMX specification. In particular, a method in an MBean server interceptor must not throw any exceptions apart from the following:

• Exceptions explicitly declared in the throws clause of the same method in the interface com.sun.jdmk.interceptor.MBeanServerInterceptor

• JMRuntimeException or a subclass of it

If an MBean server interceptor does not respect this condition, and, for example, throws a NullPointerException exception, this might have unexpected effects on calling code, which might not be protected against such behavior.