=Paper=
{{Paper
|id=Vol-1591/paper22
|storemode=property
|title=CSCB Tools: A Tool to Synthesize Pareto Optimal State Machine Models from Choreography Using Petri Nets
|pdfUrl=https://ceur-ws.org/Vol-1591/paper22.pdf
|volume=Vol-1591
|authors=Toshiyuki Miyamoto
|dblpUrl=https://dblp.org/rec/conf/apn/Miyamoto16
}}
==CSCB Tools: A Tool to Synthesize Pareto Optimal State Machine Models from Choreography Using Petri Nets==
https://ceur-ws.org/Vol-1591/paper22.pdf
CSCB Tools: A Tool to Synthesize Pareto
Optimal State Machine Models from
Choreography Using Petri Nets⋆
Toshiyuki Miyamoto1
Graduate School of Engineering, Osaka University,
Suita, Osaka 565-0871, Japan
miyamoto@eei.eng.osaka-u.ac.jp
Abstract. Application of service-oriented architecture, in which the en-
tire system is built by a combination of independent software compo-
nents, to a wide variety of computer systems is expected. The problem
to synthesize state machine models of the services from a communica-
tion diagram representing the overall specifications of service interaction
is known as the choreography realization problem. It should be minded
on automatic synthesis that software models should be understandable
to software engineers. We have proposed a method to synthesize hierar-
chical state machine models for the choreography realization problem in
former PNSEs. We have implemented the method as a plug-in of Rational
Software Architect. In this paper, we present the prototypical tool.
1 Introduction
In recent years, the internationalization of activities and information technol-
ogy in enterprises has intensified competition between companies. Under such
circumstances, service-oriented architecture (SOA)[13] has been attracting at-
tention as the architecture of information systems in enterprises. In SOA, an
information system is built by composing independent software units called ser-
vices.
In SOA, the problem to synthesize the concrete model from an abstract
specification is known as the choreography realization problem[12], in which the
abstract specification, called choreography, is defined as a set of interactions
among services, which are given in a dependency relation of messages sent and
received; the concrete model is called the service implementation and defines
the behavior of the service. This paper utilizes the communication diagram and
the state machine of UML 2.x[11] to describe the choreography and the service
implementation, respectively.
Bultan and Fu formally introduced the choreography realization problem in
[2]. They used collaboration diagrams of UML1.x and showed some conditions
for a given choreography to be realizable. In addition, they showed a method
⋆
This work was supported by KAKENHI (26330083).
336 PNSE’16 – Petri Nets and Software Engineering
to represent the service implementation as the state space in which a state was
defined as a set of unsent messages, and they also showed a method to map to
a set of finite state machines. However, it is not intelligible because the number
of states increases exponentially as the number of messages increases.
Cruz-Lemus et al. experimentally evaluated the relationship between some
metrics of state machines and the time needed to understand them[1]. According
to the result, state machines are intelligible the smaller the following metrics: the
number of simple states (NSS), the number of transitions (NT), and the number
of guards (NG).
Miyamoto et al. proposed the Construct State-machine Cutting Bridges (CSCB)
method, a method for synthesizing hierarchical state machines from a commu-
nication diagram[6, 8, 7]. In this method, dependency relations among sent and
received message events are represented by Petri nets[9]; state machines are then
synthesized. We have implemented the CSCB method as a plug-in of Rational
Software Architect (RSA) [3]
Recently, a new notion called re-constructible decomposition of acyclic re-
lations was introduced; a necessary and sufficient condition for a decomposed
relation to be re-constructible was shown[4]. Using the re-constructibility, we
have proposed an extended version of the CSCB method in [5]. In this paper, we
report the extension of the plug-in of RSA so as to support the extended CSCB
method.
2 CSCB Tools
2.1 CSCB method
The CSCB method synthesizes state machines for each service from choreog-
raphy defined by a communication diagram. At first, the method derives an
acyclic relation for each service. Second, the relations are transformed to Petri
nets. Third, when a Petri net has T-T bridges, it is modified by cutting bridges
while keeping the behavior. Finally, each Petri net is converted into a hierarchi-
cal state machine. We use RSA as the editor for communication diagrams and
the repository to store synthesized state machines.
2.2 Extended CSCB method
The result in [4] allows us to use any acyclic relation in some range. In the
extended CSCB method, a set of acyclic relations for each service is derived at
the first step. A set of state machines are synthesized and our tool selects more
intelligible state machines using the following metrics for intelligibility: NSS,
NT, NG, number of depths (ND), and sum of number of partners for all regions
(NP). Because we use several metrics, a set of Pareto optimal state machines is
selected.
T. Miyamoto: CSCB Tools 337
connect cbUML cbUML::grammer mPN
cbUML::cd cbUML::sm mPN::stateSpace
Fig. 1. Packages of CSCB Tools
Fig. 2. Screen shot
2.3 Architecture of CSCB Tools
We have implemented the synthesis function as a plug-in of RSA; one can down-
load the plug-in from the following URL:
338 PNSE’16 – Petri Nets and Software Engineering
Fig. 3. Purchase Order System
http://is.eei.eng.osaka-u.ac.jp/miyamoto/index.php?CSCB(Eng)
Fig. 1 shows packages of the CSCB Tools. We have proposed an UML sub-
set, called the subset of UML for formally describing choreography and behav-
ioral feature (cbUML), to discuss the choreography realization problem, and an
extended Petri net, called the message mark graph (MMG) [7]. cbUML is the
main package for cbUML models, cbUML::cd is the package for communication
diagrams, cbUML::sm is the package for state machines, and cbUML::grammer
defines the grammer of statements in cbUML models. mPN is the package for
MMGs and mPN::stateSpace is the package to generate reachability spaces of
MMGs, which is used in the projection method[2]. The package connect con-
nects cbUML model with RSA. Retrieving and storing UML models from and
to RSA are done through connect. Fig. 2 shows a screen-shot of the tool. We
use class and communication diagrams to define choreography.
2.4 Example
Fig. 3 shows an example choreography, which is taken from BPEL-WS 2.0 specifi-
cation[10]. The system is composed of five services: Customer, Vendor, Shipping,
Invoicing, and Scheduling. When Vendor receives order from Customer, it
sends requests to Shipping, Invoicing, and Scheduling.
The request to Shipping is shipReq, and the reply from Shipping is shipInfo.
The requests to Invoicing are productInfo and shipType; the reply from
Invoicing is invoice. Vendor sends productInfo after receiving order; it sends
shipType after receiving shipInfo. Invoicing does internal process to make an
invoice after receiving productInfo and shipType; then it sends invoice as a
T. Miyamoto: CSCB Tools 339
Fig. 4. State machine of Vendor service
reply. The request to Scheduling are productSchedule and shipSchedule.
Vendor sends productSchedule after receiving order; it sends shipSchedule
after receiving shipInfo. Vendor sends orderReply to Customer after receiving
shipInfo and invoice and sending shipSchedule.
From this communication diagram, twelve state machines were constructed.
Among the state machines, the tool selected the state machine shown in Fig. 4
as the best. The state machine behaves as follows. When Vendor receives order,
it sends productSchedule to Scheduling, productInfo to Invoicing, and
shipReq to Shipping. After that, it receives shipInfo, then it sends shipSchedule
to Shipping and shipType to Invoicing. Finally, when it receives invoice, it
sends orderReply to Customer.
Table 1. Intelligibility comparison
method NSS NT NG ND NP
projection 30 61 0 1 4
CSCB 5 15 1 4 7
extended CSCB 3 11 0 3 7
Table 1 shows the comparison result. Compared to the projection method[2],
CSCB and extended CSCB methods succeeded in reducing NSS and NT. Com-
pared to the CSCB method[7], the extended CSCB methods succeeded in syn-
thesizing more intelligible state machine. Specially, the state machine does not
have any guards and, thus, it has no implicit control flow.
340 PNSE’16 – Petri Nets and Software Engineering
3 Conclusions
In this paper, we extended the function for synthesizing state machines of our
tool. The function has been implemented as a plug-in of Rational Software Ar-
chitect. Currently, our tool can synthesize hierarchical state machines of services
from one communication diagram. Synthesizing state machines from multiple
communication diagrams is one of our interests. State machines may be modified
by designers; conformance checking of state machines should also be developed.
Our further interest is developing model checking and simulation functionalists
of communication diagrams or state machines for checking some properties of
the system.
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