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Re: A comment about changing kernels


From: Bernhard Kauer
Subject: Re: A comment about changing kernels
Date: Sat, 29 Oct 2005 09:54:44 +0200
User-agent: Mutt/1.5.9i

On Fri, Oct 28, 2005 at 04:41:08PM -0400, Jonathan S. Shapiro wrote:
> > Session based mean, that I open a session to a server, send my return 
> > endpoint
> > to it, get perhaps another session-capability from the server and use this
> > capbility to talk to the server. The server can answer my calls through my
> > initially send return endpoint.
> 
> Three questions for Bernhard:
> 
> 1. Who pays for the storage for all of these endpoint capabilities that
>    the server must retain?

Think of a server who offers session based protocols: for example a network 
stack.
A TCP/IP network server has to hold TCP connections, receive and send buffers.
In this situation accounting the resources to the client is needed, if denial of
service should be avoided. Therefore, let the client pay for the storage the
server need to keep the return endpoint.


> 2. If the client dies, how does the server learn that the session is
>    terminated and the server's endpoint capability for that client can
>    be dropped?

In the network server example: if a connection timeouts. Otherwise the parent,
who deletes the client, has to reclaim the memory  or notify the server.

 
> 3. Consider a server that has multiple clients, each with a session.
>    One of these clients invokes the server. How does the server know
>    which client it is supposed to respond to?

We use the badge for this.


    Bernhard




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