A Quantitative Model-based Selection of Web Service Reconfiguration
Honghao Gao
1
, Huaikou Miao
2
1
Computer Center, Shanghai University, 200444 Shanghai, P.R. China
2
School of Computer Engineering and Science, Shanghai University, 200444 Shanghai, P.R. China
E-mail: gaohonghao@shu.edu.cn
Abstract — Web service reconfiguration plays a critical role in
Service-Oriented Software (SOS), which provides a self-
adaptation technique to ensure the business-critical
application can be correctly worked when an SOS system is
deployed in the uncertain Internet environment. To address
this problem, the primary task is to select substitution services
for handling the current failure service, such as the atomic
service or composite service. In this paper, the service process
of Web service is initially formalized in the form of a
probabilistic timed model PTWSB at both of the behavior
level and QoS level. Then it gives two model-based
reconfigurations with different service selection demands,
mainly the single-source service reconfiguration and multi-
source service reconfiguration. Our approach has a good
potential application prospect in Service-Oriented Software.
Keywords-service selection; quantitative model checking;
synchronous product; task-oriented solution strategy
I. INTRODUCTION
Web service is considered to be the most promising
technique for Service-Oriented Software (SOS) in Service-
Oriented Computing (SOC) and Service-Oriented
Architecture (SOA), which works as plugin mode to
provide the value-added applications in which required
services can be flexibly used on demand. Since the single
service has limited functionality, complex business logic
calls for composing and integrating different kinds of cross-
domain services, utilizing not only atomic service but also
composite service. Thus, services composition approaches,
such as Orchestration and Choreography languages [1] (e.g.,
BPEL4WS, WS-Choreography, and WSCL), have been
used in commercial applications and open source research.
It contributes to business and software development. For e-
commerce, the service-oriented solution provides processes
to maximize business benefits that companies can easily
employ the existing third-party services and their interfaces
to realize inter-organizational cooperation and collaboration.
For software, the service-based architecture supporting a
rapid reuse mode and low-cost way to software
implementation has completely changed the traditional
software life cycle. However, running under the
heterogeneous, open, and collaborative Internet
environment, Web services may become faulty occasionally.
SOS is required to respond to the changes in order to avoid
service interruptions, including varying user requirements
and unstable Internet runtime environments. If the service
failure is not processed in a timely manner, it may seriously
impact the correctness and reliability of business processes
of a service-oriented software. Thus, effectively executing a
reconfiguration ensures the business-critical application is
trustworthy. One of the most challenging problems is to
select candidate Web services [6-15, 17-23].
The first issue is how to guarantee core functions will
work after deploying the selected service in service
reconfiguration. This refers to the behavior matching
requirement. The service process of business logic may
have complex dependencies. Thus, the functional
requirement verification of a Web service needs to be
executed by the temporal logic for checking the behavior
consistency. The second issue is how to ensure the
candidate service has equivalent (or similar) non-
functionality to the failure one. This refers to the
quantitative requirement. From the respect of consumers,
satisfaction relies on their user experiences and on judging
the quality of service when invoking a service, such as
timing-response, cost and reliability. The real-time property
of a Web service depends on input/output and the timing of
input/output [2]. The cost property of a Web service refers
to utilize Web service at little expense. The probability
property of a Web service provides a robustness mechanism
when users invoke service-based software. In short, a
response should provide correct values, and the value
should be output at the right time-points with lower cost
and high reliability.
The process of manually selecting a composite Web
service or replacement for the failure one is time consuming
and error-prone. Thus, in this paper, a novel model-based
approach is proposed for quantitatively selecting Web
services during service reconfiguration. It aims to employ
automata to select a suitable candidate set of services. The
service process of Web service is formalized into a
probabilistic timed
model (PTWSB) and the quantitative
reconfiguration requirement is specified in the form of
probabilistic timed computation tree logic (PTCTL). The
quantitative reconfiguration based on model checking is
divided into two patterns when considering service
selection, mainly the single-source service reconfiguration
method and multi-source service reconfiguration method.
The former tries to select a single service to replace the
failure service. If no suitable service exists, the latter
attempts to select multiple services to simulate the failure
service. Considering linear sequences illustrating property
violations can be produced by the model checker, the
quantitative counterexample is introduced to describe the
possible strategy for selecting and recommending services
when using the multi-source service reconfiguration method.
The remainder of this paper is organized as follows.
Section II introduces preliminary concepts. Section III
shows the ideal modeling service process and specifying
978-0-7695-5005-3/13 $26.00 © 2013 IEEE
DOI 10.1109/SNPD.2013.19
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2013 14th ACIS International Conference on Software Engineering, Artificial Intelligence, Networking and Parallel/Distributed
Computing
978-0-7695-5005-3/13 $26.00 © 2013 IEEE
DOI 10.1109/SNPD.2013.19
365