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From "Mike Grundvig" <m...@electrotank.com>
Subject Dumb Questions about MINA Implementation
Date Sun, 10 Sep 2006 01:14:27 GMT
Hi all; I'm having a hell of a time grasping MINA. I don't know why, but for 
some reason I just can't seem to get a handle on how to properly implement 
anything with it. I can get it working just fine but because it has many 
solutions to a single problem I always second-guess my design decisions.

Currently, I'm working with a protocol that delimits every message with a 
character. After some checking, I determined that I could simply use the 
TextLineEncoder/Decoder to process my messages if I passed in the right 
delimiter. I then created my own IoHandler and in the sessionCreate method, 
I instantiate the encoder/decoder and a ProtocolCodecFilter and just add 
them to the filter chain as the last entry. The code is basically this 
(stripped down for brevity in email):

public void sessionCreated(IoSession ioSession) throws Exception {
    ProtocolEncoder delimitedEncoder = new TextLineEncoder(defaultCharset, 
terminator);
    ProtocolDecoder delimitedDecoder = new TextLineDecoder(defaultCharset, 
terminator);
    ProtocolCodecFilter codecFilter = new 
ProtocolCodecFilter(delimitedEncoder, delimitedDecoder);
    ioSession.getFilterChain().addLast("protocol", codecFilter);
}

This all works fine, but it seems horribly inefficient to create a filter, 
encoder and decoder for each and every connection established. Particularly 
when the ioSession provides the concept of attributes that can be used to 
store stateful data. Is my implementation actually correct? It seems a 
better approach (from a performance standpoint) would be to create stateless 
versions of those objects and tie them to the IOAcceptor itself unless I'm 
missing something (which seems likely at this point).

I've seen examples that add filters to either the ioSession OR the 
ioAcceptor. What's the difference? Adding to the acceptor adds them to all 
new sessions, is that correct?

Thanks in advance for any advice/help. I appreciate it!

Michael 



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