where is PortableRemoteObject.class?

In J2SDKEE1.2.1,I can find javax.rmi.PortableRemoteObject.class,but in J2SDKEE1.3,I can not find PortableRemoteObject.class.

Who can tell me where is it?

In developing EJB,the client code contains:

" RemoteHome home=(RemoteHome)javax.rmi.PortableRemoteObject.narrow(obj,RemoteHome.class);"

Does the client application work on J2EE1.3 Reference Implements?

[400 byte] By [jordanwang0860] at [2007-9-26 8:17:11]