=Paper=
{{Paper
|id=None
|storemode=property
|title=Modular Modeling of SMIL Documents with Complex Termination Events
|pdfUrl=https://ceur-ws.org/Vol-1160/paper21.pdf
|volume=Vol-1160
|dblpUrl=https://dblp.org/rec/conf/apn/DahmaniMB14
}}
==Modular Modeling of SMIL Documents with Complex Termination Events==
https://ceur-ws.org/Vol-1160/paper21.pdf
Modular Modeling of SMIL Documents with
Complex Termination Events
Djaouida Dahmani1 , Samia Mazouz2 , and Malika Boukala1
1
MOVEP, USTHB, Algiers.
dzaouche,mboukala@usthb.dz,
2
LSI, USTHB, Algiers.
smazouz@usthb.dz
Abstract. In order to design and analyse complex real time systems,
we improve the communication mechanism of Time Recursive Petri Net
model that we have proposed in previous works. We have used our ex-
tended model, named Time ERP N + , to check the temporal coherence
of SMIL documents. This paper presents on-going work where special
attention is given to the termination events between objects having
distinct time references.
This paper summarises and extends some previous results of our work aim-
ing at controlling the temporal coherence of SMIL documents by using models
based on Time Recursive Petri net (Time RP N ) [1]. This latter is an extension
of Recursive Petri net (RP N ) with time by proposing a formal methodology for
the design and validation of component-based real-time systems with dynamic
structure, namely Time RP N . The modularity is inherent in Time RP N with-
out any extended notation. Afterwards, we have refined Time RP N model by
improving the communication mechanism between threads; the proposed version
is called Time ERP N + . In Time RP N , each thread has its own local execution
context (local place marking). No communication between threads is possible,
except birth and death relationship. When a thread T terminates, it aborts its
whole descent of threads. Only T may return results to its father-thread (which
gave birth to T ). Therefore, all aborted threads have a silent death, except T .
Whereas in Time ERP N + , communications between threads are enriched by
means of shared context (global places). Furthermore, any thread has the abil-
ity to report its death, contrary to Time RP N , where some threads have silent
death. Moreover, finitude, accessibility and boundness of Time ERP N + are de-
cidable.
A multimedia document SMIL is a collection of media. A media may be (i)
basic as an image, a video, a text or an hyper-link, or (ii) composite as a par
(resp. seq) object which plays in parallel (resp. seq) a set of media, considered as
its children. The temporal behaviour of a media is described by a set of temporal
attributes. For instance, begin and end attributes define respectively the begin-
ning and ending times of a media; it can be a known value or a synchronisation
336 PNSE’14 – Petri Nets and Software Engineering
event (e.g. end(media1) = end(media2) means that media1 must terminate
when media2 terminates). Author, who is in charge of creating such document,
can incrementally add, modify or remove any temporal relation. Therefore, his
document may become incoherent. Research in the field of temporal consistency
verification of multimedia documents covers several aspects : verification at au-
thoring stage, designing schedulers which handle synchronisation at player level
and so on. Our approach focuses on temporal consistency verification of multi-
media documents at authoring stage [2].
A SMIL document is translated into a Time ERP N + , used to check its
temporal coherence. To each SMIL media (basic or composite), a time sub-
ERP N + is associated as a simulation support. Furthermore, the transitions of
the sub-net are constrained by temporal intervals which are deduced from the
temporal attributes of the media. Also an abstract transition is attached to
the media and viewed as its interface. A firing of the media interface allows to
launch one media simulation occurrence by creating a thread which will play such
a simulation. In a previous work [2], we have modeled simple synchronisation
event between children of a same parent media. For this purpose, local places
are used within the sub-net associated with the parent media. Furthermore a
simple synchronisation event is played by the parent thread and no need to
global places. In second time, we have tackled media having distinct parents but
we have only considered relations such as begin(media1) = begin(media2) + t
or begin(media1) = end(media2) + t. We have shown that the time ERP N +
model is more suitable for such a synchronisation, characterized as complex, in
fact it allows to maintain the compactness of our modeling [3]. In this paper,
we consider terminate events such as end(media1) = begin(media2) + t or (ii)
end(media1) = end(media2) + t and explain briefly its modeling. It consists in
adding a time sub-ERP N + which is played by the initial thread. The parent
thread of media2 puts a token in a global place as soon as media2 (i) starts or
(ii) terminates. After t time units, the initial thread marks a second global place
which will force the end of the thread playing media1. Thanks to global places
and the new communication concept of time ERP N + , our modeling is modular
and reflects the structure of a SMIL document.
References
1. D. Dahmani, JM. Ilié, and M. Boukala. Time recursive PetriNets. In Transactions
on Petri Nets and Other Models of Concurrency, volume 1, pages 104–118. Springer
Verlag, 2008.
2. D. Dahmani, S. Mazouz, and M. Boukala. Modular Modeling and Analyzing of
Multimedia Documents with Repetitive Objects. In 5th International Conference on
Computer Science and Information Technology (CSIT’13), pages 308–316, Amman,
Jordan, March 2013. IEEEXplore digital library.
3. D. Dahmani, S. Mazouz, and M. Boukala. Efficient and Modular Modeling of Hi-
erarchical Multimedia Objects by Using Time ERPN+. In 4th International Con-
ference on Multimedia Computing and Systems (ICMCS’14), Marrakesh, Morocco,
April 2014. IEEE Catalog Number : CFP-14050-CDR.