DEPENDABILITY AND ROLLBACK RECOVERY FOR COMPOSITE WEB SERVICES ARUN KUMAR.M(91708205011) KARUPPASAMYPANDIAN.S(91708205035) KARTHICK.J(91708205301) Under The Guidance Of Mrs.D.Rojaramani M.Tech., Assistant Professor Department of Information Technology, Sethu Institute of Technology.

DEPENDABILITY AND ROLLBACK RECOVERY FOR COMPOSITE WEB SERVICES

PROBLEM DEFINITION & DESCRIPTION Common mode failures are possible due to a server having multiple services residing on it failing.The service execution could be blocked or experience long delays due to congestion at a particular service or broker arising from traffic. The broker is supposed to have a built-in acceptance testing mechanism that examines the results feedback from a particular web service.Reliability models assume that the failure or error arrival times are exponentially distributed. Error arrival times will be dependent on the operating state including workload of the server where the web service resides.

Modules Description: Software Reliability of the individual Web Service Implementation of Business Transaction Protocol (BTP) Blocking of a particular service Roll Back and Recovery.

software reliability of the individual web service Reliability is the probability of success or the probability that the system will perform its intended function under specified design limits. While individual web services can be used to accomplish specific tasks, there is a growing need to integrate multiple services into complex chains of web services.

Implementation of Business Transaction Protocol (BTP) BTP is a model for long-lived business transaction structured into small atomic transactions, and using cohesion to connect these atomic operations. BTP solves problems in environments with complex business interactions with potentially unreliable infrastructure over potentially unreliable communication links.  The goal of a typical business interaction is to provide a concrete completion

Blocking of a particular service In the case of central coordination, the broker is considered to have an acceptance testing mechanism that examines the results returned from a particular web service. If, however, it is unacceptable, it will involve rollback and invoke another component web service to carry out the same function as was required from the faulty component web service. In some senses, saving the state and creating checkpoints is more straightforward, as they could be associated with initiating a web service and completion of a web service. It should be noted that the recovery block approach can address both design errors, hardware server errors and channel transmission errors.

Roll Back and Recovery: We add a check pointing mechanism; it is of special interest to analyze its overhead associated with fault-free execution. The bounded set method involves a systematic decomposition into mutually exclusive sets of states and the development of upper and lower bounds for these sets. If our client application supposed removed from the group .and the sender autonomous system will be rollback his process in which it will be returned from the intermediate proxy server and it get back his respective source.

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CONCLUSION The model dynamically calculates the reliability of composite web services with rollback recovery based on the realtime reliabilities (depending on the servers loading) of the atomic web services of the composition. we determine the reliability of composite web services using the bounded set approach to manage the states explosion in the case of complex systems.

Future Enhancements In future work, we intend to extend our model to more complicated cases including the AND, Xor, and loop structures dealing with three-state models for the bounded set due to the presence of the Xor structures.. Presently our project supports only master and maestro cards. In Future we are planning to implement the same process for Visa and Visa Electron cards as well. Other type of cards such as I-mint and sudexo cards

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