We did this on a project for the department of immigration - a swing
app connecting to a remote database.
Our solution was to put serialised method calls (ie, an object
containing method name and arguments) into a HTTP request, and have a
servlet at the other end unwrap the call and invoke the server.
Doing this allowed us to get through proxies and firewalls, because
rather than dealing with sockets, we were dealing with HTTP requests
and webservers. However, it's a pretty heavyweight solution.
For what you describe: (to say, "add a new question to the database"
or "give me a list of all the subjects", "someone changed the list of
subjects" or "please log in"), RMI is the way to go if you are just
running on a local network and getting a socket connection is not a
problem. Doing this allows you to ignore keeping sockets open and
stuff like that. To do "two way" calls (the server can asynchronously
call the client):
0) The server sets up an RMI server object
1) The client must set up an object to act as an RMI server. This is
the "callback" object.
2) The client locates the server RMI object (this is the tricky bit)
3) The client logs into the server, passing it's callback as a
parameter (as well as login info, typically).
4) The server passes back to the client an object implementing the
interface that the client actually wants
4) The server keeps track of client sessions, occasionally sending
them "are you still alive?" calls.
To maintain "state", calls from the client to the server need to
contain a reference to the session. There are a couple of ways to do
this: the server can build an RMI object for each connected client
(the easy way), or it can have one RMI server which all the clients
use (the not-so-easy way).
Note that on the client side, calls received on the "callback" object
are not on the swing thread, so you will need to do a
SwingUtilities.invokeLater() to handle them.
Would you like some sample code?
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Java-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/java-dev/email@hidden
