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From Niklas Therning <>
Subject Re: [mina] Refactoring MINA IoFilterChain (Was: IoFilters: DIRMINA-121 / 122)
Date Tue, 15 Nov 2005 08:29:57 GMT
Niklas Therning wrote:

> ...
>Yes, setIoProcessor() isn't very nice, I agree. And I don't have a
>solution for it except that copying the chain passed to setFilterChain()
>into something like an IoProcessorAwareFilterChain. I can't see how the
>above solves this. How does the wrapped chain know where to route
>write() / close() calls? Or is it just to prevent setIoProcessor() from
>being called?
I have a solution now! :)

I just realized that when calling IoSession.write() the concrete 
IoSession implementation will always know the final destination of the 
write event. For SocketSessionImpl the final destination is always 

So the IoFilterChain methods for downstream events look like this:

void write( IoSession session, WriteRequest writeRequest, IoProcessor p 
) throws Exception;

SocketSessionImpl's write() method looks like this:

public WriteFuture write( Object message ) {
    this.filterChain.write(this, new WriteRequest(), 

Provided that SocketIoProcessor implements IoProcessor. I think you get 
the point. The ChainedFilterChain will always know the next filter chain 
to filter through and can wrap it in an 
IoFilterChainToIoProcessorAdapter object.

Bottom line: setIoProcessor() WON'T BE NEEDED! This approach makes 
IoFilterChain totally stateless which means the same filter chain can be 
reused for different ports if the user wants that (though that would 
probably not be advisable).

The only sacrifice I see right now is the IoFilterChain.getNextFilter() 
methods. They would not return a proper NextFilter instance.

If it's ok with Dave I would like to see what he comes up with before we 
abondon this approach. Dave, if you don't want to spend your time on 
something that might get thrown away, please let me know and I can take 


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