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From Horace Pinker <flipcode2...@yahoo.com>
Subject [mina] Re: mina 0.9.4 - io/business logic decoupling with threads
Date Wed, 13 Sep 2006 11:59:12 GMT
hi trustin,

i now setup the acceptor as described in your post:

            SocketAcceptorConfig cfg = new SocketAcceptorConfig();
            cfg.setThreadModel(ThreadModel.MANUAL);

            DefaultIoFilterChainBuilder chain = cfg.getFilterChain();

            ThreadPoolFilter firstPool = new ThreadPoolFilter();
            firstPool.setMaximumPoolSize(32);
            chain.addLast("firstpool", firstPool);

            chain.addLast("codec", new ProtocolCodecFilter(new TextLineCodecFactory()));

            ThreadPoolFilter secondPool = new ThreadPoolFilter();
            secondPool.setMaximumPoolSize(32);
            chain.addLast("secondpool", secondPool);
            
            Acceptor = new SocketAcceptor();
            Acceptor.bind(new InetSocketAddress(IP, Port), new NET_SessionHandler(this), cfg);

i had to remove some code from sessionCreated:

    public void sessionCreated(IoSession _IOSession)
    {
        ...
        
        TextLineCodecFactory codec = new TextLineCodecFactory();
        codec.setDecoderMaxLineLength(1024);
        
        ...

        _IOSession.getFilterChain().addFirst("protocolFilter", new ProtocolCodecFilter(codec));
        
        ...
    }

i assume the chain is now setup like this because of the cfg i provided when i bound the acceptor?

in general i prefer the way it is now, because i did not like the code in the sessionCreated
function anyhow :D

some questions regarding the 2 pools:

1stpool:

- by default (without a custom pool setup) only this pool would exist?

- if only this pool exists it will be used to execute io->filter AND filter->handler?

- is is guaranteed that filter->handler for a specific connection is called SEQUENTIALLY
which would in my case guarantee that ONE and ONLY ONE textline of a specific connection is
forwarded to my handler?

2ndpool:

-  if this is available the 1st pool will only exectute io->filter while this 2nd pool

with only execute filter->handler?

- i assume this 2nd pool would be beneficial if business logic (in the handlers) may be expensive
(jdbc stuff i.e.), because with one pool this bl would block the filters? if this is the case,
would the io (sending/receiving) be blocked, too?

thanks!

cheers,
horace

Trustin Lee <trustin@gmail.com> wrote: Hi Horace,

On 9/1/06, Horace Pinker  wrote:
>
> i'm using mina 0.9.4.


We will release 0.9.5 soon, I think you'd better upgrade soon because
0.9.5contains a *lot* of fixes.

this is how i set up the acceptor:
>
> Acceptor = new SocketAcceptor();
> Acceptor.bind(new InetSocketAddress(Port), new NET_SessionHandler(this));


Looks good.

i read the docs and found some info regarding ThreadModel, however this info
> seems to be outdated for 0.9.4.


I am sorry about that.  Please let us know any JavaDoc which is outdated.
We need to fix it.

is by default iologic and businesslogic decoupled and in separate
> threadpools in mina 0.9.4?


We need to clarify things a little bit here.  Basically there are three
parties when you program a network application:

* I/O code - MINA transport implementation (e.g. SocketAcceptor)
* Protocol encoder and decoder - ProtocolCodecFilter in MINA
* Business logic - IoHandler in MINA

By default, a thread pool is inserted between the I/O code and the protocol
codec.  You can also insert another thread pool between the codec and the
business logic, but you have to insert it manually.

To insert the second thread pool:

SocketAcceptorConfig cfg = new SocketAcceptorConfig();

// Set the thread model to 'manual'
cfg.setThreadModel(ThreadModel.MANUAL);

DefaultIoFilterChainBuilder chain = cfg.getFilterChain();

// Add the first thread pool
ThreadPoolFilter firstPool = new ThreadPoolFilter();
firstPool.getThreadPool().setMaximumPoolSize(32); // max # of threads
chain.addLast("firstpool", firstPool);

// Add the codec
chain.addLast("codec", new ProtocolCodecFilter(...));

// Add the second thread pool
ThreadPoolFilter secondPool = new ThreadPoolFilter();
...
chain.addLast("secondpool", secondPool);

Otherwise, you could create your own ThreadModel implementation that inserts
thread pools as you want:

public class MyThreadModel implements ThreadModel {

    public void buildChain(IoSession session) {
        IoFilterChain chain = session.getFilterChain();
        chain.addFirst("pool", new ThreadPoolFilter(...));
        // insert the second thread pool next to the codec.
        chain.addAfter("codec", "pool-2", new ThreadPoolFilter(...));
    }
}

I think the second example is much cleaner and separates the responsibility
of classes properly.  Its weakness is that you have to assume the name of
the codec filter.

HTH,
Trustin
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