SOA Web Services

1. A Novel Robust & Fault tolerance Framework for
Webservices using WS-I
*
Specification
Akhilesh Kumar Pandey
1,3
, Abhishek Kumar
1,4
and Farahnaz Rezaeian Zade
2,5
1
School of Computer Engineering , KIIT University, Bhubaneswar, Orissa, India
2
Fooland Institute Of Technology, Fooland Shahr, Isfahan, Iran
infoakhileshpandey@gmail.com
3
, abhikumar695@gmail.com
4
, fr.rezaeeian@gmail.com
5
Abstract— Fault handling never became trivial task for the
applications since decades as it is abnormal situation that may
occur when application running in a production environment. So
coming to the distributed application component such as
webservice also fault handling needs more sophisticated
approach to ensure QoS of service. Recently, Webservices has
become a defacto standard for developing loosely coupled
distributed application component due to the support of
interoperability irrespective of the platform and language
however still webservice architecture fails to provide robustness
and fault tolerance so that business organizations can provide
services to the consumer more accurately and effectively without
failing 24*7 hours. This work proposes a robust and fault
tolerance framework to handle faults in webservices and repair
the faults in webservices in order to provide smooth and efficient
services. A set of diversity and repair actions are also proposed
that provides normal resolution of services from manual
breakdown of services. In the framework all the stack of
webservice standards are used along with fault tolerance
capability in existing webservice architecture. Mainly, proposed
framework uses two base component that is Agent for
maintaining replicas and Controller for fault detection, fault
notification and fault confinement in order to provide robustness
and fault tolerance in existing webservice architecture.
Keywords—SOA; Robust; Fault Handling; Webservices;
SOAP; Interoperability; Fault tolerance; SCA.
I. INTRODUCTION
SOA(Service-Oriented Architecture) is an architectural
paradigm that improves accuracy, correctness & efficiency of
business organizations in order to fulfill business requirement
[1]. Service is a self contained interoperable loosely coupled
distributed component. There is a set of technologies to
implement Service Oriented Architecture (SOA) but
webservices is the best way to realize SOA. Web service
technology follows some stack of standards such as WSDL,
SOAP, which uses XML to provide interoperability [2-4].
SOA also can be implemented through SCA (Service
Component Architecture) [5].
Usually, Service oriented systems are made by
heterogeneous webservices that are distributed across network
and provided by business organizations . Developing highly
reliable, actuate and efficient service oriented system is tedious
task due to the dynamic behavior of webservices. Webservices is
the technology that allows us to build interoperable, loosely
coupled, distributed software component, It also allows a
application to expose complex business logic over the network.
Webservice software component are not only platform
independent, these are even language independent which means it
allows to develop software component using Perl, Python, C,
C++, Java or .NET . In order to access this consumer component
can be developed in any one of technology like C, C++, Java or
.NET.
To build interoperable distributed component, every
software vender started defining their own stack of standards
such as transport protocol, language for exchanging data and
description. In such cases interoperability will never become
reality. Later, it was realized by every software vendor present
in the market that the fact that they can't build interoperable
component.
Currently, Webservice have become very important part of
critical application due to this availability of application
becomes dependent on the webservices used by the
applications. QoS & availability is a very important part of
critical application. However, there is no stack of standards for
robustness and fault tolerance in webservices. Considering
robustness and fault tolerance as an critical issue , there many
attempt have been taken place by the industry and academic
researchers but still their proposal lacks to provide enough
support for robustness and fault tolerance as their work don't
take the advantage of specification given by WS-I [6] .
The proposed work focuses on the robustness and fault
tolerance(FT) in webservices. The main idea in this paper is to
propose framework that can provide high QoS (quality of
service) and availability. Proposed framework takes an
advantage of existing webservice architecture and WS-I
specification in order to ensure compatibility with stack of
webservice standards[6]. The proposed framework takes an
advantage of webservice architecture along with two new
major components that is Controller and Agent.
The rest of paper is organized as follows , related work on
fault tolerance in distributed technologies and Webservices is
described in section 2. A basic idea about the technology is
presented in section 3. A novel robust and fault tolerance

2. framework using WS-I specification is proposed in section 4,
it also includes the description about two major components of
proposed framework. Description of proposed framework with
step by step presented in section 5. In section 6 conclusion and
future work have been described.
II. RELATED WORK
With the help of related data and information, it is a
universally accepted fact that fault tolerance can be achieved
with duplicating hardware and software resources [7] [8]. For
instance, if services are duplicated and one of them fails, the
remaining one can still ensure the desired output.
Due to the high demand of web services, issues related to
Fault Tolerance are becoming critical. Therefore an
appropriate solution is needed to solve such type of issues. In
the recent years, several fault handling methodologies and
frameworks have been proposed for web services and SOA.
But due to a high demand of web services it still requires a
more theatrical background and robust and fault tolerant
framework to provide high availably and quality of service .
Vijay Dialani et al.[9] have proposed a transparent fault
tolerance for Web services based architectures which provide
capacity for monitoring the individual instance and service
host. Chen Liu et al.[10] have proposed a rule-based exception
handling approaches in SOA, in which they introduced some
basic rules, categories of exception with strategies to handle it.
Huang et al.[11] have proposed a runtime monitoring
composite web service through stateful aspect extension where
they followed stateful aspect extension approach to monitor
web service at runtime. Roman Vaculfn et al.[12] have
proposed exception handling model with appropriate recovery
actions for semantic web services that is purely based on
OWL-S. Wen jiajia et al.[13] have proposed a system for
handling exception in BPEL process through multi-policy, but
proposed work lacks to provide reliability and extensibility of
web services. M.G. In [14] author proposed the mechanism of
recovering faulty Web apps using Service discovery in which
they described the mechanism for handling faults using
various kinds of the recovery mechanism. In their work they
introduced a self healing architecture for identifying faults and
taking appropriate actions based on faults. In [15], service
oriented architecture(SOA) based service recovery framework
has been proposed. In this work's author introduced an
algorithm to select recovery action based on exception
servility but it still needs various recovery actions and
compatibility based on web service stack of standards such as
WSDL, SOAP and UDDI. M. Panahi et al.[16] have defined
the a middleware architecture to support an accountable
service oriented architecture that consists of three components
ASB, AA and Agent. Their work mainly focuses to mange
web service faults that to only those are closely related to
performance. But in their work various kinds of faults in
services are not considered. B. Pernici et al.[17] proposed a
work for identifying the fault type and methodologies to fix
various types of faults. They categorized the various types of
faults based on state such as permanent, transient, which are
determined by Bayesian classification. However, their work
requires more concrete emphasis to identify the type of fault
related to fault duration and criteria to choose methodologies.
Tamir et al. [18] proposed a fault tolerance model for
webserver which detects server errors and forwards requests to
a replica server to avoid service failures. In [19], Author
proposed a fault tolerant architecture for grid applications.
This model takes a help of a passive replication approach in
order to provide fault tolerance.
III. TECHNOLOGY BACKGROUND
This section contains basic concepts of web services
related to the fault handling in distributed technologies and
web services.
Initially We have applications which are designed to run on
one machine. Like when we develop applications in 'C' language ,
it can execute on a box and can talk to other applications which
are running on the same box. But now distributed technology
solves the above problems and allows to build applications which
is not only executed on a machine and talk to other applications
on the same machine, these applications should also be able to
access or communicate with other applications which are running
on a different machine.
The web service is technology that allows us to build an
interoperable distributed application component. To build
interoperable distributed application component, every
software vendor in the industry started defining their own
standards. In such case interoperability never will become
reality. With a time it was realized by every software vendor
that we can't build independently an interoperable distributed
application component, unless everyone has agreed upon same
standards. There comes a WS-I[6] organization which is
formed to build open standards for building interoperable
distributed application component. WS-I released BP1.0
specification document, the document contains a set of
guidelines or standards that must be used to develop a
distributed interoperable component .
Web services have three main parts in its architecture [1-
3,5] that is a service provider, service consumer and UDDI
registry [21].In order to achieve interoperability in
webservices common language for exchange data is used that
is XML but having XML is not enough to exchange data
between two systems. We need a layer on top of it to classify
the information. For instance, We don't send only business
data for communication, along with business data, we may
need to send transport specific data or some helper data. So
using XML we can't differentiate such kind of information.
Hence in such cases SOAP is used that can differentiate
business data and helper data . In the proposed framework we
use a SOAP binding protocol for interaction.
This paper focuses in the field of robustness and FT(Fault
Tolerance) in webservices. The key idea is to provide a
framework that can offer QoS with high availability of web
services. Proposed framework uses the existing webservice
architecture to ensure compatibility with stack of webservices
standards.

3. IV. PROPOSED FRAMEWORK
Our framework is based on the existing web service
architecture and WS-I organization specification with fault
tolerance and robust capability in order to provide QoS and
achieve interoperability up to the mark.
A. Avizienis et al.[20] given basic concept and dependable
and secure computing in which different types of faults are
discussed that may arise during service invocation.
The proposed framework includes two major components
that are responsible to mange replica for diversity actions,
fault diagnosis and appropriate recovery actions.
In our proposed framework, configuration stage is
responsible for publication of web services where the provider
of service uses the UDDI registry for registering web service
replica.
On execution stage, an Agent module is used to create
web-service replicas. Once the web - service replica is created
Agent performs different test to ensure the service that has to
be used. In this stage Controller job is to detect the faults. It
also does the verification of the web service during its
execution. If a fault gets propagated, the Controller
communicates with Agent for selection of appropriate web
service that is replicated across various nodes.
There are two major modules of proposed framework that is
Controller and Agent .
1. Controller: Controller module in framework
provides QoS to consumers by taking different kind
of necessary actions. It also gives facility to provide
for detecting faults and taking actions based upon
faults.
Figure 1: A Novel Robust & Fault tolerance Framework for Webservices using WS-I* Specification

4. The main responsibility of Controller for fault
detection, notification and confinement. It gives
notification to the Agent if webservice renders with a
fault during the service execution. For example, if
webservice gets a fault during its execution, then
Controller gives fault notification to the Agent in
order to assign appropriate web service replica to
continue normal execution from manual breakdown.
In the framework Controller gets a request from
consumer with an appropriate web service type,
including operations and parameters for service
execution. Then Controller takes an help of Agent in
order to perform mapping of service type in
available webservice replica.
2. Agent: The main job of the agent is to manage replicas
across the nodes. It creates service replica using
UDDI registry [21]. The Agent also checks presence
of replica during replica selection stage.
V. DESCRIPTION OF PROPOSED FRAMEWORK
In the figure 1.0, There can be a separate Controller for
each and every web service consumer. In diagram Agent and
UDDI can be located remotely at different locations. Here
multiple Agent can be deployed in different locations with the
Controller. The proposed framework work as presented in
following steps:-
1. During execution of application, the consumer sends
a request of required type.
2. Consumer request passes to Agent through
Controller.
3. Agent searches web-service of required service type
from UDDI registry [21].
4. Now Agent performs an availability test for
choosing the appropriate web service replica that has
to be used.
5. Next, Agent returns web-service address of the
controller. Now the consumer can invoke the needed
operation/ method in the selected service through the
returned access point.
6. The Controller does the verification of service
execution. During execution, if any, faults occur,
then controller takes an help of replica and continues
the manual execution of the application.
7. Now, when service execution is completed results
are reported back to the consumer.
Here, the replica creation takes an advantage of UDDI
standards [21]. The extended UDDI allows a refined web-
service replica selection that is based on the availability,
interoperability and response time .
VI. CONCLUSION AND FUTURE WORK
In this paper a robust and fault tolerant framework for web
services using WS-I
*
specifications is proposed. Our
framework uses existing web service architecture, including
two more major component Controller and Agent to ensure
robustness and fault tolerance in web services. The main
benefit of web-service technology is interoperability
irrespective of the language and platform through open stack
of web service standards such as SOAP, WSDL, XML etc.
In future work, the idea is to propose a load balancing
algorithm for avoiding from consumer to forward multiple
requests to the same web service replica. Further work is also
to propose fault tolerance framework for mobile web services
in which proposed work may use REST instead of SOAP as
smart devices will have very less resources in terms of
memory. So by keeping hardware as well as software
resources as an issue, the idea is there to use a REST
interaction style of web services for mobile devices instead of
traditional SOAP.
ACKNOWLEDGMENT
This work is provisionally supported by KIIT University,
Bhubaneswar, India. Our sincere thanks to KIIT University,
Bhubaneswar, India for providing resources to complete this
work.
REFERENCES
[1] E. Thomas. SOA Principles of Service Design. Prentice Hall
International, 1st edition, 2007.
[2] W3C. Simple Object Access Protocol (SOAP)
1.1. http://www.w3.org/TR/soap/.
[3] W3C. Web Services Description Language (WSDL).
http://www.w3.org/TR/wsdl.
[4] OASIS. Universal Description, Discovery and Integration(UDDI).
http://uddi.org/.
[5] B. Margolis and J. Sharpe. SOA for the Business Developer - Concepts,
BPEL, and SCA. MC Press, 1st edition, 2007.
[6] WS Interoperability Organization. Web Service Interoperability (WS-I),
2005.
[7] B. Kim, “Reliability analysis of real-time controllers with dual-modular
temporal redundancy,” Proc. of the Sixth International Conference on
Real-Time Computing Systems and Applications (RTCSA)1999, pp.364-
371, 13-15 Dec. 1999.
[8] B. Kim, “Reliability analysis of real-time controllers with dual-modular
temporal redundancy,” Proceeding of the 6th International Conference
on Real-Time Computing Systems and Applications (RTCSA) 1999,
pp.364-371, 13-15 Dec. 1999.
[9] V. Dialani, S. Miles, L. Moreau, D. D. Roure, and M. Luck.
"Transparent fault tolerance for Web services based architectures". In
Proceedings of the 8th International Euro-Par Conference on Parallel
Processing, pages 889–898. Springer, 2002.
[10] Chen Liu, Yanting Xu, D., and Xaiyu, L. “A rule- based exception
handlings approach in SOA”. International Conference on Computer
Application and System Modeling (2010).

5. [11] Huang T, Wu GQ, Wei J, "Runtime Monitoring Composite Web
Services Through Stateful Aspect Extension", Journal Of Computer
Science And Technology, vol. 24, pp. 294- 308, 2009.
[12] Roman Vaculfn, Kevin Wiesner, Katia Sycara "exception handling and
recovery of semantic web services", 4th International Conference on
Networking and Services, ICNS 2008, Pages 217-222 ,2008.
[13] Wen Jiajia, Chen Junliang, Peng Yong and Xu Meng. "a multi policy
exception handling system for bpel process", First Intl. Conf. on
Communications and Networking in China, ChinaCom '06, 2007.
[14] M.G. Fungini and E. Mussi, “recovery of faulty web applications
through service discovery,” Proc. First International Workshop Semantic
Matchmaking and Resource Retrieval: Issues and Perspectives (SMR
2006), Sept. 2006, pages. 67-80.
[15] C. Jie-Ying, W. Yong-Jun, and X. Yi, “soa-based service recovery
framework,” Proceeding the 9th International Conference. Web-Age
Information Management (WAIM 2008), July 2008, pages. 629-635.
[16] M. Panahi, K.J. Lin, Y. Zhang, S.H. Chang, J. Zhang, and L. Varela,
“The LLAMA Middleware Support for Accountable Service-Oriented
Architecture,” Proceeding the 6th International Conference Service
Oriented Computing (ICSOC 2008), Lecture Notes in Computer Science
5364, Springer- Verlag, Dec. 2008, pp. 180-194.
[17] B. Pernici, and A.M. Rosati., “Automatic Learning of Repair Strategies
for Web Services,” Proceeding. 5th IEEE European Conf. Web services
(ECOWS 2007), IEEE Computer Society, Nov. 2007. Pages. 119-128.
[18] N. Aghdaie and Y. Tamir. "Client transparent fault-tolerant web
service". In Proceedings of the IEEE International Conference on
Performance, Computing, and Communications, pages 209-216. IEEE
Computer Society, 2001.
[19] D. Zagorodnov, X. Zhang, M. Hiltunen, K. Marzullo and R. D.
"Schlichting. Fault-tolerant grid services using primary backup:
feasibility and performance". In Proceedding IEEE International
Conference. on Cluster Computing, pages 105-114. IEEE-CS, 2004.
[20] A. Avizienis, J. C. Laprie, B. Randell, C. Landwehr. Basic concepts
and taxonomy of dependable and secure computing. IEEE Transactions
on Dependable and Secure Computing, pages 11–33, 2004.
[21] UDDI specifications,
http://uddi.org/pubs/uddiv3.0.2-20041019.html