[aadl]: Cyclic Immediate Connections in AADL

[Andrew Gacek]

I'm still a bit confused. Are cyclic immediate connections between two
systems allowed? If we don't know what is inside the systems, we can't
yet say if the cycle prohibits schedulability. Does it boil down to
saying that there can't be any cyclic immediate connections among
threads in a final instance model?

-Andrew

On Wed, Dec 17, 2014 at 5:30 PM, Julien Delange <jdelange at sei.cmu.edu> wrote:
> Hi Andrew,
>
>
>
> From what I remembered (Peter might have materials about that), there is no
> check in OSATE to you can declare them. However, as you mentioned, they
> cannot be realized from an implementation point of view.
>
> We can create an errata in the standard to add an explicit statement about
> them.
>
>
>
> Julien.
>
>
>
>
>
> From: sae-aadl-users-bounces+jdelange=sei.cmu.edu at lists.sei.cmu.edu
> [mailto:sae-aadl-users-bounces+jdelange=sei.cmu.edu at lists.sei.cmu.edu] On
> Behalf Of Andrew Gacek
> Sent: Wednesday, December 17, 2014 4:01 PM
> To: sae-aadl-users at lists.sei.cmu.edu
> Subject: [aadl]: Cyclic Immediate Connections in AADL
>
>
>
> Hi,
>
>
>
> Are cycles of immediate connections between subcomponents allowed in AADL? I
> couldn't find anything definitive in the AADL spec about it. The spec talks
> about scheduling in such a way that strongly suggests cyclic connections are
> not allowed, but no clear statement of it being disallowed. The best I've
> found is this line:
>
>
>
> "Cyclic sequences of immediate connections are not permitted since they
> cannot be achieved. "
>
>
>
> From "Pattern-Based Analysis of an Embedded Real-time System Architecture."
> Is there a definitive statement that such connection cycles are not allowed?
> I know OSATE doesn't complain about them:
>
>
>
>   thread io
>
>             features
>
>       o : out data port;
>
>       i : in data port;
>
>   end io;
>
>
>
>   process proc
>
>             end proc;
>
>
>
>   process implementation proc.impl
>
>             subcomponents
>
>              A: thread io;
>
>              B: thread io;
>
>
>
>             connections
>
>       AtoB : port A.o -> B.i;
>
>       BtoA : port B.o -> A.i;
>
>   end proc.impl;
>
>
>
> Thanks,
>
> Andrew Gacek