[okl4-developer] cell to threads communication

[Josh Matthews]

Hi Hannes,
What you're looking for are "Reply Capabilities". These are temporary
(one-shot) capabilities that are created on receipt of a synchronous IPC -
intended exactly for client-server type interactions such that the server
does not need to possess a capability to every possible client (and can
instead trust that as long as a client possesses a capability to the server,
that client is valid and can be replied to).

Check out section B-18.4 of the OKL4 3.0 Library reference manual - you can
see the reply_cap that you receive as an output parameter to
okl4_message_wait.

Note that this is only for synchronous communications - you appear to be
using asynch/notify. Is it possible for you to use synchronous comms?

Josh

On Fri, Oct 2, 2009 at 5:15 AM, Hannes Payer <
hannes.payer at cs.uni-salzburg.at> wrote:

>
> Well, this question seems to be somehow related to the question asked in
> "Capability Passing in OKL4 3.0"
> http://wiki.ok-labs.com/forum#nabble-td2241729. Can I dynamically create
> these capabilities in the server cell at runtime? A client thread would
> have
> to pass some information(?) to the server cell. The server would then have
> to create the necessary capability and send the result back to the given
> client thread. Is this possible in OKL4?
>
> -H
>
>
>
> Hannes Payer wrote:
> >
> > Hi,
> >
> > how can multiple threads running in one cell communicate with another
> > cell? I looked at the available OKL4 documentation and played around with
> > the API, but I am not sure how to get this done.
> >
> > The following program works for me:
> > There are 2 cells running in the system. One is a server cell performing
> a
> > calculation based on client input and returning the result to the client.
> > The server cell waits for a notification (okl4_notify_wait) from the
> > client cell. Whenever the client cell wants to communicate with the
> server
> > it writes data to a known shared memory location and sends the server
> cell
> > a notification (okl4_notify_send) and waits for a notification from the
> > server for the result. The server cell looks-up the input in shared
> > memory, computes the result, writes the result to shared memory and sends
> > the client a notification. This example is very similar to the decrypt
> > demo of the OKL4 examples and on a cell-to-cell communication basis this
> > system works.
> >
> > My question:
> > Can I implement this example also with multiple threads running in the
> > client cell where each single thread communicates with the server cell?
> > How does the server cell get the capability to send a given thread from
> > the client cell a notification? Do I have to stick to cell-to-cell
> > communication and multiplex the messages from the server cell on the
> > client cell side?
> >
> > I hope my problem description is precise enough. Thank you very much for
> > your help.
> >
> > -H
> >
>
> --
> View this message in context:
> http://n2.nabble.com/cell-to-threads-communication-tp3750541p3754410.html
> Sent from the OKL4 Community Forum mailing list archive at Nabble.com.
>
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