Gregg Wonderly wrote:
Peter Firmstone wrote:
Gregg Wonderly wrote:
I think that there are lots of choices about service location and
activation of proxies. The MarshalledObject mechanism allows one to
wrap proxies at any point and make them available for remote
consumption.
Downloading a proxy via http instead of Reggie works fine.
Good point.
We need to document things and provide the convienence methods and
classes that will promote standard practices.
We can set up an experimental documents area on svn, scanned
scratchings etc while we're hashing things out? The crawler lookup
service might discard non conformant proxies to assist in promoting
standard practices. The lookup service might also advertise what
River platform versions it's compatible with.
Another thought. The MarshalledObject mechanism seems simple to use,
but not quite. The problem is that there is the RMIClassLoaderSPI
mechanism that requires support for the annotation in the
MarshalledObject, to already exist. Further, things that commonly go
along with the annotation, such as URL protocol support have to
already exist too. Thus, any particular Jini deployment or use almost
always has to be preplanned from the client and server perspective,
unless you don't use anything different for annotations.
Things like conditional download, cached download etc need to be done
in ways that are invisible to the system, or they have to be part of
your planning. The use of httpmd: for example, requires
-Djava.protocol.handler.pkgs=net.jini.url on the command line, but
what if you are not responsible for the JVMs lifecycle?
I still have this gut feeling that we need to rethink how
MarshalledObject is used and how we might make the whole mechanism
managed more as a Thread or ThreadPool based mechanism instead of a
whole JVM mechanism. It is true that context class loader mechanisms
help contain the view of foreign classes. But we need the ability to
"allow injection" of unmarshalling support classes so that a service
can be more independent of the clients environment. I don't have a
clear view of what yet, I'm just mulling around about this.
Gregg Wonderly
Thanks Gregg, I found a good article that might be helpful too:
http://accu.org/index.php/journals/1434
Cheers,
Peter.
