Rollback Recovery Approach for Complex Composite Web Services to Enhance Reliability of Service

Rollback Recovery Approach for Complex Composite Web Services to Enhance Reliability of Service

B. Muruganantham(1), Dr. K. Vivekanandan(2), Dipayan Mondal(1)

(1)Department of Computer Science and Engineering

SRM University, Kattankulathur 603203, Chennai, Tamilnadu, India (2)Department of Computer Science and Engineering Pondichery Engineering College, Puduchery, India

Abstract–The composition of existing services plays an important role to fulfill user requirement which creates an attention towards Web Service Composition technology in current era. Existing works focus on the rollback recovery process incomposingweb services in a complex way;but the limitations of those works lie on the methods or operators which are used for composing web services and execute them in serial parallel manner. By implementing complex operator for composing web services, proposed method increase throughput of service composing process and at the same time provide more choice in front of service consumer. Use of ANDoperator and OR operatormay lead failure possibilities.To overcome that failure possibilities, an auto checkpoint creation algorithm is used which serves both as rollback recovery mechanism and enhancing the reliability of service.

Keywords: Service Composition, Rollback Recovery, Checkpoint, Quality of service.

1. INTRODUCTION

   Web service is a self-contained, modular application that can be described, published, located, and invoked over the Web [1]. It is platform-neutral and based on open standards. Web services can be combined with each other in different ways to create business processes that enable us to interact with consumer, developer, and provider [2] [3].

   Web service is a technology that allows applications to communicate with each other in a platform-independent and programming language-independent manner [4]. It is a software interface that describes a collection of operations that can be accessed over network through standardized XML messaging. It uses protocols based on the XML language to describe an operation to execute or exchange of data with another Web service.

   The web services are described using the Web Service Description Language (WSDL) and the described web services are stored in the repository called Universal Description, Discovery and Integration (UDDI) [5].

   Web as a platform is used to establish integration among applications by web services. Web Service gives input to the

   business process and receives output after performing interaction between those processes. A Web Service can be invoked by any application, irrespective of language, platform, and operating systems due to its standalone characteristic [6][7].

   To reduce the complexity,Web Service encapsulates business processes into reusable components.Also improves interoperability by working as a wrapper around platform- specific applications. Web Servicecan improve developing process of application much faster than before [4][5]. A Web Service provides simple and reliable way to accustomexisting systems with new applications and services.

   Syntax based searchworks on phrase matching concept, which will produce result by comparing given phrase or words with documents or services exists in repository, which may produce some irrelevant output to the users request. Semantic based search [8] produce appropriate output, because searching procedure performed according to users intention.

2. RELATEDWORK

   H. Elfawal Mansour and T. Dillon has developed a service- oriented reliability model that dynamically calculates the reliability of composite webservices with rollback recovery based on the real-time reliabilities of the atomic web services of the composition. They have performed web service composition using OR, XOR operator separately and used rollback recovery approach for that composed model [1].

   WitoldAbramowicz, Monika Kaczmarek andDominikZyskowski, describe in detail about the composition structure or Web services and parameters required to measure Quality of Service of any web service composition [2].

   Jia Zhang and Liang-Jie Zhang, describe criteria of reliability of Web services-oriented systems,and discuss

   how to design and generate test cases toconduct tests over Web services. They developed prototype system to test the effectiveness and efficiency of their algorithms. The preliminary results show that their approach facilitates the testing of services-orientedsystems [7].

   Jiannong Cao, G.H. Chan andTharam S. Dillon and Weijia.Jia,propose anovel approach to designing Checkpointing and rollbackalgorithms using mobile agents as an aid. Using mobileagent leads to a reduction of the total amount ofcommunication and allows us to design algorithms thattake the advantage of the most up to date systeminformation for decision making. It also allows developing algorithms to implement flexible and adaptivepolicies. A mobile agent enabled hybrid algorithmcombining independent and coordinated Checkpointingis proposed. A prototype of the algorithms is developedusing IBMs Aglets [9].

3. METHODOLOGY

   Proposed method implementsrollback recovery approach on web service composition [1][9], which composed web

   In the Fig-1, three web services namely web service A, web service B and web service C, are participated in the composition. Web service B has its three substitutes B1, B2 and B3. If any one of them fails then other replaced that failed one. So, according to proposed composition process, AND operator used to combined web service A with web service B, but web service B has three substitutes, among those services any one successful one selected using OR operator and then combined with next web service C.

   The use of AND operator may lead failure possibility. This problem solved by developing an auto checkpoint creation algorithm [1][9], which used to mark previous successful web service of current one. If current web service fails to execute then no need to go for new composition, rather it will ask user to choose an alternative for that failed one, and start execution form that checkpoint. Using this concept proposed method save execution time, execution cost, increase performance, and enhanced reliability of web services. Fig-2 describes implementation of auto checkpoint creation algorithm in proposed method.

   WEB SERVICE

   services using complex operators [2][3]. An algorithm namely auto checkpoint creation developed to implement

   CHECKPOINT MARK

   B1 CHECKPOINT MARK

   rollback recovery approach. Proposed work mainly concentrates on the reliability of web service composition to enhance reliability of service [2][7].

   Web services defined and published in the repository or UDDI (Universal Descriptive Discovery and Integration).

   WEB SERVICE A

   AND

   WEB SERVICE B2

   WEB SERVICE B3

   WEB

   OR SERVICE C

   When a service consumer requests for a web service, a semantic based search performed in the UDDI to find out related web services. It generates appropriate services to fulfill user requirement because of semantic based search

   [8] rather than syntactic search.

   Matched web services (based on user request) are composed using AND operator and OR operator [2][3]. AND operator is used because proposed system work on the principle that if we need to combined more than one web services together to process an users request then all web service must be executed successfully. If any one of them fails to execute then total composition must stop execution. OR operator is used to provide flexibility of the web service. If on of the services in the composition fails to execute then it will replace that service with its substitute. Fig-1 describes over all web service composition process.

   WEB SERVICE B1

   WEB

   Fig 2: Implementation of auto checkpoint creation algorithm in web service composition method.

   Lets assume thatthe whole composition includes air ticket booking, taxi booking and a hotel booking of a consumer. The whole composition needs a proper execution process which must be carried out sequentially, that means without booking of air tickets, the process of booking a taxi or hotel should not be performed by the service provider.This type of functional behaviour of each web service is called the web service choreography.

4. ARCHITECTURE OF PROPOSED METHOD

   The overall architecture mainly divided into three processes. First one deals with describing and publishing web services by the service provider. In this process a service provider describe a web service using WSDL and then publish it or stored that web service in the repository or UDDI.

   Second process deals with service discovery. In this work we use semantic based [8] service discovery method. Based

   WEB

   SERVICE A

   AND

   WEB SERVICE

   B2

   WEB SERVICE B3

   OR SERVICE C

   on service consumer request for web service this module finds out appropriate matched services from the repository. Due to use of semantic based search procedure it will generate result according to consumer intension.

   Fig 1: Web service composition process using AND operator and OR operator.

   Finally the third process performs composition web services discovered in second process to meets consumer

   requirement. In this process composition of web services performed using AND operator and OR operator [2][3]. To make this composition consistent and fault tolerant, a rollback recovery mechanism [1][9] used which basically worked based on auto checkpoint creation algorithm [9]. Fig-3 describes over all architecture of proposed work.

   Table1: Airlines services retrieved from repository.

   SERVICE PROVIDER

   DEFINE/DESCIRBE (WSDL)

   WEB SERVICE

   Flight No.	Flight Name	Time of Departure	Price Per Person
   IA024	Indian Airlines	10:05	5800
   KA428	Kingfisher Airlines	13:20	4200
   JA768	Jet Airways	18:10	3750

   PUBLISH

   REPOSITORY (UDDI)

   1. If the consumer wants to book a taxi from airport to the hotel the following information will be displayed by fetching taxi service from the repository which is shown in

      SERVICE CONSUMER

      SERVICE REQUEST (FIND)

      SERVICE DISCOVERY

      SEMANTIC BASED MATCHING

      MATCHED SERVICE

      WEB SERVICE

      SEMANTIC BASED CLASSIFICATION OF WEB SERVICES

      the Table 2.

      Table2: Taxi services retrieved from repository.

      COMPOSE WEB SERVICES USING AND & OR OPERATOR

      SERVICE COMPOSER

      WEB

      SWERVICE

      ROLLBACK RECOVERY UNIT BASED ON CHECKPOINTING ALGORITHM

      COMPOSED WEB SERVICES

      Car Name	Price Per KM
      Scorpio	30
      Audi	45
      Mercedes Benz	60

   2. Further, if the consumer wants to book hotel then he/she can choose the feasible hotel form the list generated by the service discovery unit (Table 3).

   Table3: Hotel services retrieved from repository.

   Hotel Name	St ar	Facility	Price Per Day
   The Taj Bengal	5	In the heart of the city	2000
   The Grand Oberoy	7	Near to Airport	3000
   Hotel Kohinoor	3	Near to Temple	1800

   Fig 3: System Architecture for Web service composition.

5. EXPERIMENTALRESULT

   To implement our work practically, mainly three services namely airline booking, taxi booking and hotel booking are defined in the repository. According to the consumer requirement,using these three services main composition performed. The main focus of this composition technique is: if a web service of the composition, execute successfully then only it will go for execution of next service. Otherwise it will ask consumer to select an alternative service of the failed one and then processed with execution of that new web service.

   For example a service consumer want to travel from Chennai to Kolkata, the following are the steps involved in the web service composition:

   (i) At first the service consumer goes for required airline booking service by selecting one airline service from the given list of service. The list generated based on flight's departure time and the cost per person i.e. by default cheapest airline comes first in the list.The user also can go with either cost constraint or time constraints according his/her need.Service discovery unit generated list shown in Table 1.

   After completion of selecting web services by the service consumer, the service composer performed service composition by booking all the services selected by the consumer.

6. CONCLUSION

   Finally conclude that proposed work concentrated on semantic based service discovery and complex composite web services composition using two operators: AND operator and OR operator. Use of these two complex operators may responsible for failure in composition; we have introduced the rollback recovery mechanism based on auto checkpoint creation algorithm to avoid it.Basically, we are concentrating on a flawless service composition to enhance reliability of service.

7. FUTURE WORK

As a future enhancement of this work more parameters regarding QoS issues, more parameters like latency time, robustness, charging method etc. may take in account in this system and implemented to enhance QoS. Moreover, other complex operators can be used to compose web services to produce accurate result.

REFERENCES

1. H. Elfawal Mansour,T. Dillon,Dependability and RollbackRecoveryfor Composite Web Services, 1939- 1374/2011 IEEE.

2. WitoldAbramowicz, Monika Kaczmarek, DominikZyskowski, Duality in Web Services Reliability, 0-7695-2522-9/2006, IEEE.

3. Kiepuszewski B., terHofstede A.H.M., van der Aalst W.M.P., Fundamentals of control flow in workflows, ActaInformatica 39, 143209 (2003).

4. Xiaona Wu, Bixin Li, Rui Song, Cuicui Liu, Shanshan Qi, Trust-based Service Composition and Optimization, 2012 19th Asia-Pacific Software Engineering Conference, 1530-1362/ 2012 IEEE.

5. Joe M. Tekli, Ernesto Damiani, Richard Chbeir, and Gabriele Gianini, SOAP Processing Performance and Enhancement, IEEE Transaction on Services Computing, Vol. 5, No. 3, July-September 2012.

6. Hongxia Tong, Jian Cao, Shensheng Zhang, and Minglu Li, A Distributed Algorithm for Web Service Composition Based on Service Agent Model, IEEE Transaction on Services Computing, Vol. 22, No. 12, December 2011.

7. Jia Zhang, Liang-Jie Zhang, Criteria Analysis and Validation of the Reliability of Web Services-oriented Systems, 0-7695-2409-5/05,IEEE.

8. Hongjiang Cao, GuihuaNie, Donglin Chen, Research on the Web Service Composition Based on Semantic, 978-1-4244-6349-7/2010 IEEE.

9. Jiannong Cao, G.H. Chan, Tharam S. Dillon, Weijia. Jia,Checkpointing and Rollback of Wide-Area Distributed Applications Using Mobile Agents, 0- 7695-0990-8/200 IEEE.