Vol-3170/poster3

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id	Vol-3170/poster3
wikidataid	Q117351469→Q117351469
title	Parametrisation of CSA-Nets
pdfUrl	https://ceur-ws.org/Vol-3170/poster3.pdf
dblpUrl	https://dblp.org/rec/conf/apn/Alahmadi22
volume	Vol-3170→Vol-3170
session	→

Parametrisation of CSA-Nets

Parametrisation of CSA-nets
Mohammed Alahmadi1
1 School of Computing, Newcastle University

Science Square, Newcastle upon Tyne, NE4 5TG, United Kingdom



   The modelling approach proposed in this paper has its origin in the structured occurrence
nets [1] that are a Petri net-based model for the representation of the execution behavior of complex
evolving systems. They are an extension of occurrence nets which represent the causality and
concurrency information relating to a single system execution. In general, a structured occurrence
net consists of several occurrence nets linked through different types of formal relationships.
   A particular formal model we are using in this paper are the communication structured
occurrence nets (CSA-nets), which are generalisations of communication structured occurrence
nets (a subclass of structured occurrence nets [1]), where individual acyclic nets are linked by
buffer places capable of modelling both asynchronous and synchronous communication between
different subsystems.

Master buffer places
A CSA-net consists of sets of acyclic nets that communicate with each other through a set of buffer
places. This can generate an excessive number of buffer places which makes the model hard to
visualise and analyse, especially for large CSA-nets. Therefore, in [2] we proposed to use master
buffer places (MBPs), which introduce conciseness to CSA-nets by collapsing/folding (some of)
the original buffer places into master buffer places. This allows buffer places to represent more
than one token at a time to avoid having a large number of distinct buffer places. Additionally,
it may allow the component acyclic nets to communicate through a unique buffer place. Inside
a master buffer place, there is a set of tokens represented by unique colours. A specific token
appears in the master buffer place without conflicting with other tokens in each execution since
the net is colour-safe due to the fact that the original CSA-net was safe. This enhances CSA-net
visualisation contributing to a more readable and understandable model.

Parameterised CSA-nets
We will apply the concept of folding to other components of CSA-nets while preserving the overall
behaviour. The idea is to determine the set of the components that are behaving identically, and
then representing them as a single substructure. This uses typed parameters to achieve the desired
effect through passing coloured tokens to parameterised transition. Parameterisation is used to
change system outputs by changing its input parameters (in other words, different parameters can
be used to define a set of different outputs). The main advantage of parameterisations is that the

International Workshop on Petri Nets and Software Engineering, June 21, 2022, Bergen, Norway
" m.s.h.alahmadi2@ncl.ac.uk (M. Alahmadi)
                                    © 2022 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
 CEUR
 Workshop
 Proceedings
               http://ceur-ws.org
               ISSN 1613-0073       CEUR Workshop Proceedings (CEUR-WS.org)
�                                                p2                      p3
                                                           b
                              p1                                                          p4
                                       a                                         c
                                                p5                      p6
                                                           d



                        (a)                        q1                q2



                                                p7         e            p8



                                                            f

                                             r2 : {p2}    {b}      r3 : {p3}
                          r1 : {p1}                        t2
                                       {a}                                       {c}   r4 : {p4}
                              p1:1
                              p1 : 2   t1                                        t3
                                                          {d}
                                                           t4
                                             r5 : {p5}             r6 : {p6}

                        (b)                                     q : {q1 , q2 }

                                             r7 : {p7}
                                                                   r8 : {p8}
                                                p7:1
                                               p7 : 2      t5
                                                         {e, f }

Figure 1: A CSA-net (a); and the result of introducing master buffer place and folding (b).


structure of a system model does not need to be re-built each time it is run. Such an approach
will allow the reuse of the model multiple times and increase comprehension and make larger
systems under investigation easier to handle. Figure 1 illustrates the transition from the original
CSA -nets to their parameterised versions.



References
[1] M. Koutny, B. Randell, Structured occurrence nets: A formalism for aiding system failure
    prevention and analysis techniques, Fundamenta Informaticae 97 (2009) 41–91.
[2] M. Alahmadi, Master channel places for communication structured acyclic nets, in:
    M. Köhler-Bussmeier, E. Kindler, H. Rölke (Eds.), Proceedings of the International Workshop
    on Petri Nets and Software Engineering 2021, volume 2907 of CEUR Workshop Proceedings,
    CEUR-WS.org, 2021, pp. 233–240.
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