[jira] Reopened: (DIRMINA-208) Allow datagrams to be directed to a specific destination on a per-datagram instead of a per-session basis.

["Trustin Lee (JIRA)" <ji...@apache.org>]

     [ http://issues.apache.org/jira/browse/DIRMINA-208?page=all ]
     
Trustin Lee reopened DIRMINA-208:
---------------------------------


I am terribly sorry for this problem.  I will apply your patch soon.  

> Allow datagrams to be directed to a specific destination on a per-datagram instead of a per-session basis.
> ----------------------------------------------------------------------------------------------------------
>
>          Key: DIRMINA-208
>          URL: http://issues.apache.org/jira/browse/DIRMINA-208
>      Project: Directory MINA
>         Type: Wish

>     Versions: 0.9.3
>     Reporter: Jörg Henne
>     Assignee: Trustin Lee
>      Fix For: 0.9.5
>  Attachments: pcf.patch
>
> [this is a copy of a message I sent to the mailing-list a few days ago]
> A few weeks ago I started to work on the DS DHCP server. Work has progressed so far that clients can successfully register IP addresses with the server and all, although the code is still unfit for general consumption.
> Ir order to implement the DHCP functionality, however, it was necessary to apply a minor patch to the MINA code base. The patch is necessitated by the fact that packets which are received via broadcast from a DHCP client don't have a proper source address. As a consequence, the reply messages must also be broadcast (or, in some cases sent by unicast to a different address). The existing code created a new MINA IoSession per message in order to handle this case, causing quite a lot of overhead and, worse, a new thread which lingered even after it was done.
> In order to do away with the overhead, I introduced a special session attribute which allows me to re-direct a message while it is sent like this:
>            InetSocketAddress isa = determineMessageDestination( request, reply );
>            session.setAttribute( "destination", isa );
>            session.write( reply );
> This property is used in DatagramAcceptorDelegate.flush(DatagramSessionImpl) to override the message destination address like this:
> ...
>            if ( !key.isValid() )
>            {
>                continue;
>            }
>            // HACK: allow destination to be overridden using session attribute.
>            SocketAddress destination = session.getRemoteAddress();
>            Object d = session.getAttribute( "destination" );
>            if ( null != d && d instanceof SocketAddress )
>                destination = ( SocketAddress ) d;
>            int writtenBytes = ch.send( buf.buf(), destination );
> ...
> I am not too happy with this hack, but it was easy and worked. I you could come up with a more general and elegant solution, I'd be more than happy.
> Joerg Henne

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