[aadl]: Cyclic Immediate Connections in AADL

[Julien Delange]

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
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