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From Niklas Therning <nik...@trillian.se>
Subject Re: Thread Model
Date Tue, 07 Mar 2006 14:59:42 GMT
peter royal wrote:

>> Yes, I didn't think about that possibility. But why not have  
>> something like the following:
>>   IoAcceptor acceptor = ...;
>>   IoHandlerFactory factory = ...;
>>   acceptor.accept(address, factory);
>> where IoHandlerFactory is an interface that has the responsibility  to 
>> create IoHandlers. This factory would be used by the acceptor to  
>> create an IoHandler whenever a new session is accepted.
>> This way, both the client-side and server-side IoHandler could  safely 
>> use state in instance variables. This seems more consistent  to me.
> I guess it just depends on what is the more common case. In my  
> experience, I have no problems with everything flowing into a single  
> IoHandler on the server side. So I would want an IoHandlerFactory  that 
> just returned the same instance each time. Whichever way it is  
> implemented, I think it would be a valuable contribution to MINA.
> -pete

If the handler is per session there's no need to pass in the session in 
all methods, is it? IMO it would be nicer to have a new interface:

interface SingleSessionIoHandler {
   void sessionOpened();
   void messageReceived(Object message);
   void sessionClosed();

implementation of this interface would typically store the session as an 
instance variable.

The factory interface would look like:

interface SingleSessionIoHandlerFactory {
   SingleSessionIoHandler create(IoSession session);

To achieve this in MINA you could implement a special IoHandler which 
delegates to a SingleSessionIoHandler which it gets from the session:

public class SingleSessionIoHandlerDelegate implements IoHandler {
   SingleSessionIoHandlerFactory factory;
   SingleSessionIoHandlerDelegate(SingleSessionIoHandlerFactory factory){
     this.factory = factory;
   void sessionCreated(IoSession session) {
     SingleSessionIoHandler handler = factory.create(session);
     session.setAttribute("handler", handler);
   void sessionOpened(IoSession session) {
     SingleSessionIoHandler handler = session.getAttribute("handler");
   void messageReceived(IoSession session, Object message) {
     SingleSessionIoHandler handler = session.getAttribute("handler");

To create an acceptor you would simply do:

IoAcceptor acceptor = ...;
SingleSessionIoHandlerFactory  factory = ...;
acceptor.accept(address, new SingleSessionIoHandlerDelegate(factory));

My point is that there's no need to modify the IoAcceptor interface to 
support this kind of behaviour. I see no harm in including something 
like this in MINA. Simon, if you have a patch please add it to JIRA and 
we'll consider it.


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