The object importer enables applets to call a method on a remote
object running on the Webserver (the main class of this
package).
To access the remote
object, the applet first calls lookupObject() and
obtains a proxy object, which is a reference to that object.
The class name of the proxy object is identical to that of
the remote object.
The proxy object provides the same set of methods as the remote object.
If one of the methods is invoked on the proxy object,
the invocation is delegated to the remote object.
From the viewpoint of the applet, therefore, the two objects are
identical. The applet can access the object on the server
with the regular Java syntax without concern about the actual
location.
The methods remotely called by the applet must be public.
This is true even if the applet's class and the remote object's classs
belong to the same package.
If class X is a class of remote objects, a subclass of X must be
also a class of remote objects. On the other hand, this restriction
is not applied to the superclass of X. The class X does not have to
contain a constructor taking no arguments.
The parameters to a remote method is passed in the call-by-value
manner. Thus all the parameter classes must implement
java.io.Serializable. However, if the parameter is the
proxy object, the reference to the remote object instead of a copy of
the object is passed to the method.
Because of the limitations of the current implementation,
- The parameter objects cannot contain the proxy
object as a field value.
- If class
C is of the remote object, then
the applet cannot instantiate C locally or remotely.
All the exceptions thrown by the remote object are converted
into RemoteException. Since this exception is a subclass
of RuntimeException, the caller method does not need
to catch the exception. However, good programs should catch
the RuntimeException.
See Also: javassist.tools.rmi.AppletServer
See Also: javassist.tools.rmi.RemoteException
See Also: javassist.tools.web.Viewer | 