A novel approach to multiformalism
performance modeling by composition of
basic modeling primitives
A Dissertation Defense
Enrico Barbierato
University of Turin, Italy
February 2013
Agenda
Multiformalism;
 State of the art;
 The SYMTHESys framework;
 Applications;
 Originality;
 Conclusions;
 Future work

Multiformalism

Multiformalism has
emerged as a
sound technique
showing how a
complex model
can be described
as the composition
of a set of submodels;
Composability: key aspects
The capacity to
assemble different
components in one
system;
 It can be considered
from a syntactic (a) or
a semantic (b) point of
view;
 Solution Integration;

a
b
State of the art

Formalisms:
–
–
–
–

Process Algebra;
Petri Nets-based algebra;
Queueing Petri Nets;
…
Frameworks:
– Möbius, OsMoSys, …

Tools:
– ATOM3…
SIMTHESys

A framework for the definition of new formalisms and the
automatic generation of related solvers, that allows the
combination of more formalisms in the same model.

Structured Infrastructure for Multiformalism modeling and Testing of
Heterogeneous formalisms and Extensions for Systems
FDL
Formalisms are described by the Formalism Description
Language (FDL) documents, which declare all their
modeling primitives
<fdl>
<elementType name="CAMWA">
<propertyType name="Description" type="String" default="An OSSP model" storage="static"/>
<propertyType name="id" type="String" default="" storage="static"/>
<implements ref="hasSubElements"/>
<implements ref="ExpEventModel"/>
<behavior name="InitEvents" return="void">
<code> for(ElementType T : allSubElements) { if(T instanceof ExpEventModel) {
((ExpEventModel)T).InitEvents();}}
</code>
</behavior>
…
</fdl>
SIMTHESys ElementType

ElementType:
– Properties (a constant, a variable or a result);
– Behaviors;
…
<elementType name="Place">
<!-- Interfaces -->
<implements ref="ElementOccupancy"/>
<!-- Properties -->
<property Type name="id" type="String"
default="" storage="static"/>
<property Type name="Tokens" type="int"
default="0" storage="dynamic"/>
<property Type name="MeanTokens"
type="Result" storage="computed"/>
…
Excerpt of the SPN FDL
…
<behavior name="getOccupancy“ return="int">
<code>
return getTokens();
</code>
</behavior>
…
Excerpt of the SPN FDL
SIMTHESys Interfaces

An elementType uses:
– solver interfaces to define which solving engine(s) should be used
with it;
– behavioral interfaces to re-use existing abstractions.
<fdl>
<elementType name="FCQN_SPN">
<!-- Special Interfaces -->
<implements ref="hasSubElements"/>
<!-- Interfaces -->
<implements ref="ExpEventModel"/>
<uses ref="ProbWeight"/>
<uses ref="PushPull"/>
<uses ref="Active"/>
<uses ref="FCQueueEvent"/>
<uses ref="ExpEventSolver"/>
…
</fdl>
SIMTHESys Interfaces

An elementType implements a behavioral
interface by explicitly defining behaviors and
properties specified in it.
<interface>
<behavior name="getOccupancy" return="int"/>
<behavior name="setOccupancy" return="void">
<parameter name="o" type="int"/>
</behavior>
<behavior name="addOccupancy" return="void">
<parameter name="o" type="int"/>
</behavior>
</interface>
ElementOccupancy interface
<elementType name="Place">
<!-- Interfaces -->
<implements ref="ElementOccupancy"/>
…
<behavior name="getOccupancy“ return="int">
<code>
return getTokens();
</code>
</behavior>
…
FDL file excerpt for SPN
SIMTHESys Interfaces

An elementType implements a solver
helper interface:
<interface>
<behavior name="InitEvents" return="void"/>
<behavior
name="computeStateRewards "return="double[]"/>
<behavior name="countStateRewards" return="int"/>
<behavior name="setStateRewards" return="void">
<parameter name="r" type="Result[]"/>
</behavior>
…
<fdl>
<elementType name="SPN">
<!-- Special Interfaces -->
<implements ref="ExpEventModel"/>
<uses
ref="hasSubElements"/>
<uses ref="ExpEventSolver"/>
…
FDL file for SPN (excerpt )
ExpEventModel interface (excerpt)
InitEvents behavior

A formalism defines a behavior called
InitEvents:
…
<behavior name="InitEvents“ return="void">
<code>
for(Transition T : sub_Transition) {
if(T.isActive()) {Transition _T = T;
((ExpEventSolver)getModel().getSolver()).schedule("T.fire()", T.getRate,
T.getId(), 1.0);}}
</code>
</behavior>
…
Excerpt of FDL
Schedule behavior

The solution engines expose a behavior
Schedule that is used by the implementations
of the InitEvents behavior to define what must
be executed whenever an event occurs;
<behavior name="InitEvents“ return="void">
<code>
for(Transition T : sub_Transition) {
if(T.isActive()) {Transition _T = T;
((ExpEventSolver)getModel().getSolver()).schedule("T.fire()", T.getRate,
T.getId(), 1.0);}}
</code>
</behavior>
Excerpt of FDL
MDL
A file describing the model according to the FDL file
in a Model Definition Language (MDL), XMLbased:
<mdl fdl="CAMWA.fdl">
<CAMWA id="CAMWA" Description="Un_modello_di_prova">
<CheckGe id="Arc_GE_01" from="In" to="Degradation0" weight="1"/>
<CheckGe id="Arc_GE_02" from="In" to="Crash0" />
<RateControl id="Arc_RC_05" from="Degradation0" to="Srv“ weight="1"/>
<CheckLt id="Arc_LT_01" from="Crash0" to="Srv" />
<CheckLt id="Arc_LT_02" from="Rejuvenation0" to="Srv" />
<CheckLt id="Arc_LT_03" from="Degradation0" to="Srv" />
<OSSP id="OSSP0" >
<Degradation id="Degradation0" nPhases="2" Phase="0"
phaseRate="1.15;1.25;" phaseDeg="1;0.9" />
…
</mdl>
Excerpt of MDL
Formalism families

Exponential Event Formalisms (EEF)
– Primitives represent entities capable of
generating events;
– Such events (that can be used to represent
the firing of a PN transition, or the end of the
service in a queue) are characterized by the
fact that they occur after an exponentially
distributed time;
More formalism families
Exponential and Immediate Events
Formalisms (EIEF);
 Labelled Exponential Events Formalism
(LEEF);
 Labelled Fluid Events Formalisms (LFEF);

Solution Engines

The framework currently provides some
solving engines for performance evaluation:
– Classic event based simulators;
– Solvers designed to generate Continuous Time
Markov Chains (CTMCs) and perform steady
state and transient analysis
Performance Indices

Formalisms may be characterized by
performance indices calculated by using State
Rewards and Impulse Rewards;
<RESULTS>
<SPNS>
<SPN>
<ID>Serv2br</ID><BOUNDED>false</BOUNDED>
<PLACE>P1<MEANTOKENS>3.0000000000000004</MEANTOKENS></PLACE>
<PLACE>P2<MEANTOKENS>2.0 </MEANTOKENS></PLACE>
<TRANSITION>T1<THROUGHPUT>4.163336342344338E-06</THROUGHPUT></TRANSITION>
</SPN>
</SPNS>
</RESULTS>
Excerpt of a RESULT file
SIMTHESysER Architecture and
Workflow: FDL Analyzer
SIMTHESysER Architecture and
Workflow: MDL Parser
SIMTHESysER Architecture and
Workflow
Applications
1) A motivating example: closed TFCQN with
three servers;
Enrico Barbierato, Marco Gribaudo, Mauro Iacono, Defining Formalisms for
Performance Evaluation With SIMTHESys. Electr. Notes Theor. Comput. Sci. 275:
37-51 (2011);
Applications
2) A multiformalism performance oriented model
verifying some conditions;
Barbierato E, Gribaudo M, Iacono M. (2011). Exploiting multiformalism models for testing
and performance evaluation in SIMTHESys, Proceedings of 5th International ICST
Conference on Performance Evaluation Methodologies and Tools,ICST, ISBN:978-1-93696809-1, DOI:10.4108/icst.valuetools.2011.245727
Applications
3) A formal definition of an
exception handling
mechanism for
multiformalism models;
Enrico Barbierato, Marco Gribaudo, Mauro Iacono, Stefano Marrone:
Performability Modeling of Exceptions-Aware Systems in Multiformalism
Tools. ASMTA 2011: 257-272;
Applications
4-5) Two approaches (of increasing complexity) adding
software rejuvenation features to performance models;
- Enrico Barbierato, Marco Gribaudo, Mauro Iacono, The SIMTHESys multiformalism
modeling framework. Computers & Mathematics with Applications 64(12): 3828-3839
(2012);
- Enrico Barbierato, Andrea Bobbio, Marco Gribaudo, Mauro Iacono: Multiformalism to
Support Software Rejuvenation Modeling. ISSRE Workshops 2012: 271-276
Applications
6) A performance evaluation of SOA-based
applications;
Enrico Barbierato, Mauro Iacono, Stefano Marrone (2012): PerfBPEL: A graphbased approach for the performance analysis of BPEL SOA applications.
VALUETOOLS 2012: 64-73
Applications
7) A case study showing how product-form solution
theory can couple with multiformalism compositional
modeling techniques.
Barbierato E., Dei Rossi G., Gribaudo M., Iacono M., Marin A. (2012).
Exploiting product forms solution techniques in multiformalism
modeling. Electr. Notes Theor. Comput. Sci, to appear;
Applications

8) Modeling applications

based on the mapreduce paradigm
E. Barbierato, M. Gribaudo, M. Iacono, A
Performance Modeling Language For Big Data
Architectures. 27th European conference on
modelling and simulation (ECMS 2013). IEEE
Soc. German Chapter, ISBN: 978-0-9564944-6-7,
DOI: 10.7148/2013-0511
9) Language for what-if
analysis for Big Data
application designers
E. Barbierato, M. Gribaudo, M.
Iacono, Performance Evaluation of NoSQL BigData applications using multi-formalism models.
Future generation computer systems, Elsevier,
ISSN: 0167-739X, DOI:
10.1016/j.future.2013.12.036
Originality of SIMTHESys
SIMTHESys separates the component defining
the formalism from the component solving the
model;
Originality of SIMTHESys

Flexibility:
– new formalisms (or extension of the existing
ones) can be easily added to the framework
by creating a new FDL file;

Solution integration:
– SIMTHESys derives the underlying CTMC
from the analyzed model; in this way, it is not
necessary to consider mechanisms sharing
results between sub-models.
Conclusions

SIMTHESys is an ongoing project that
defines a framework for the design of
multiformalism performance evaluation
models:
Future Work
– The definition of Formalisms and Models
by using the concept of inheritance;
– The definition of a Proprietary Language
for Behaviors;
– New formalism families and applications.
Publications

Journals:
[2014] Enrico Barbierato, Marco Gribaudo, Mauro Iacono, Modeling
and evaluating the effects of Big Data storage resource allocation
in global scale cloud architectures. International Journal of Data
Warehousing and Mining, ISSN: 1548-3924, DOI: (to appear);
[2014] E. Barbierato, M. Gribaudo, M. Iacono, Performance
Evaluation of NoSQL Big-Data applications using multi-formalism
models. Future generation computer systems, Elsevier, ISSN:
0167-739X, DOI: 10.1016/j.future.2013.12.036;
Publications
[2012] M. Iacono, E. Barbierato, M. Gribaudo, The SIMTHESys
Multiformalism Modeling Framework. Computer & mathematics with
applications, vol. 64, num. 12, pp. 3828-3839 (December 2012),
Elsevier, ISSN: 0898-1221, DOI: 10.1016/j.camwa.2012.03.009
[2011] E. Barbierato, M. Gribaudo, M. Iacono, Defining formalisms for
performance evaluation with SIMTHESys. Electronic notes in
theoretical computer science, vol. 275, pp. 37-51, Elsevier, ISSN:
1571-0661, DOI: 10.1016/j.entcs.2011.09.004
Publications

Contributions in edited print books:
[2014] Enrico Barbierato, Mauro Iacono, Marco
Gribaudo, Multiformalism and multisolution strategies for system
performances evaluation. QUADS, (to appear)2012: 271-276
[2014] E. Barbierato, Multiformalism modeling composability in
SIMTHESys, IGI-Global, ISBN: 978-1-4666-4659-9, DOI: 10.4018/9781-4666-4659-9
[2011] E. Barbierato, M. Gribaudo, M. Iacono, S.
Marrone, Performability modeling of exceptions-aware systems in
multiformalism tools. Analytical and Stochastic Modeling Techniques
and Applications, LNCS 6751, pp. 257-272, Springer-Verlag, ISBN:
978-3-642-21712-8, DOI: 10.1007/978-3-642-21713-5_19
Publications

Conferences:
[2013] E. Barbierato, M. Gribaudo, M. Iacono, Modeling Apache Hive based
applications in Big Data architectures. VALUETOOLS 2013, 7th
International Conference on Performance Evaluation Methodologies and
Tools, Torino, Italy, December 10-12, 2013
[2013] E. Barbierato, M. Gribaudo, M. Iacono, A Performance Modeling
Language For Big Data Architectures. 27th European conference on
modelling and simulation (ECMS 2013). IEEE Soc. German Chapter, ISBN:
978-0-9564944-6-7, DOI: 10.7148/2013-0511
Publications
[2012] E. Barbierato, A. Bobbio, M. Gribaudo, M. Iacono, Multiformalism
to Support Software Rejuvenation Modeling. IEEE 23rd International
Symposium on Software Reliability Engineering Workshops (ISSREW),
27-30 Nov. 2012, pp.271-276, IEEE, ISBN: 978-0-7695-4928-6, DOI:
10.1109/ISSREW.2012.92
[2012] E. Barbierato, M. Iacono, S. Marrone, PerfBPEL: a graph-based
approach for the performance analysis of BPEL SOA applications.
Proceedings of Valuetools 2012, 6th International Conference on
Performance Evaluation Methodologies and Tools. Carg�se (France),
October 9-12, 2012, ISBN: 978-1-936968-63-3, DOI:
10.4108/valuetools.2012.250340
Publications
[2011] E. Barbierato, M. Gribaudo, M. Iacono, Exploiting multiformalism
models for testing and performance evaluation in SIMTHESys. Proceedings
of 5th International ICST Conference on Performance Evaluation
Methodologies and Tools - VALUETOOLS 2011, Cachan (France), May 1620, 2011, ICST, ISBN: 978-1-936968-09-1, DOI:
10.4108/icst.valuetools.2011.245727
[2011] E. Barbierato, D. Cerotti and M. Gribaudo, A tool suite for modelling
spatial interdependencies of distributed systems with Markovian Agents, in
Proceedings of the 8th European conference on Computer Performance
Engineering, ser. EPEW 2011. Berlin, Heidelberg: Springer-Verlag, 2011,
pp. 280 - 294.