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Groups > comp.os.linux.development.apps > #389

Re: long lasting client socket connection

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On 2012-01-12, Bill M <wpmccormick@just_about_everywhere.com> wrote:
> I'm working on a socket client app that makes a connection to a server 
> and leaves it open. Thinking that since he's repeatedly asking 
> questions, there's little point in wasting time closing and reopening 
> again. Are there any good design patterns out there for this I should 
> take a look at?

Yes, the Null Node Pattern: when you don't want something to happen
(like closing and re-opening), then omit the lines of code that would cause
that to happen.

:)

But seriously, noe thing you have to watch out for is keeping such connections
idle for too long. It's almost impossible to avoid such an application being
deployed by someone in a scenario where the client connets trhough one (or
more) NAT gateways to the server. When these routers don't see any activity
between a pair of destinations, they will expire the mapping entry, and then
your connection is gone.

So you might want to include in your design the provision for keepalive
ping messages (in either direction: server or client initiated).

You probably need some kind of layered design: some objects representing the
server session, which hides a protocol for exchanging multiple messages with
the server within one session.

That layer can hide the connecting and re-connecting from the higher
application layers.

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long lasting client socket connection Bill M <wpmccormick@just_about_everywhere.com> - 2012-01-12 16:04 -0600
  Re: long lasting client socket connection Kaz Kylheku <kaz@kylheku.com> - 2012-01-12 22:21 +0000
    Re: long lasting client socket connection Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-01-13 14:54 +0000
      Re: long lasting client socket connection Bill M <wpmccormick@just_about_everywhere.com> - 2012-01-13 15:58 -0600
        Re: long lasting client socket connection Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-01-13 22:17 +0000
          Re: long lasting client socket connection Bill M <wpmccormick@just_about_everywhere.com> - 2012-01-14 14:43 -0600
        Re: long lasting client socket connection Kaz Kylheku <kaz@kylheku.com> - 2012-01-13 22:38 +0000
          Re: long lasting client socket connection Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-01-14 00:49 +0000

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