Atomicity Analysis for Service Composition

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Atomicity Analysis for Service Composition"

By

Mr. Chunyang Ye


Abstract

Service Oriented Architecture (SOA) is an emerging software engineering
paradigm for developing distributed applications in the Internet era. In
this paradigm, web services from different organizations are composed to
realize business goals. To safeguard application consistency in such an
environment, atomicity is a desirable property for a service composition,
in the sense that the service composition could either terminate
successfully or abort without any side effects. However, conventional
database transactions are inapplicable in such an environment due to the
long-running, distributed, autonomous and heterogeneous nature of web
services. Instead, exception handling, a weak consistency approach, is
often adopted to resolve application inconsistency based on the concept of
atomicity sphere, a structured criterion for the atomicity property of
service compositions.

In this thesis, we propose a process algebraic framework to study the
atomicity property in a service composition using the exception handling
approach. We discuss the following three research issues:

1) The global analysis of atomicity sphere for a service composition. In a
service composition, service providers usually provide only abstract
public views of their services to service consumers. These public views
expose only partial information of their services. Therefore, it is
difficult to analyze the atomicity sphere of a service composition using
existing work because full comprehensive information about the provided
services is needed. To address this issue, we propose an approach to
publishing the atomicity information of services in their public views.
Service consumers could then use these public views to check the atomicity
sphere in a service composition instead of using the services.

2) The local analysis of atomicity sphere in a service composition. In
some situations, besides the details of their services, organizations may
also not be willing to share information about their collaborators with
the other collaborators in a service composition due to privacy concerns
or business reasons. To check the atomicity sphere of a service
composition in such scenarios, the global analysis approach is
incompetent. To address this issue, we propose an alternative way to check
the atomicity sphere of a service composition using a local analysis
approach.

3) The detection and resolution of atomicity violations caused by implicit
interactions in a service composition. Concurrent execution of services
may lead to implicit interactions between services (i.e., resource
sharing). Such implicit interactions may also cause atomicity violations
at runtime even if a service composition satisfies the atomicity sphere.
To address this issue, we propose an approach to identify only afflicted
implicit interactions in a service composition, and suppress their threats
to the atomicity property with extra behaviour constraints.

We evaluate the framework of our proposal based on examples modeled after
a couple of real life applications and the associated experimental
results.


Date:			Monday, 28 July 2008

Time:			10:00a.m.-12:00noon

Venue:			Room 3501
			Lifts 25-26

Chairman:		Prof. Bing Zeng (ECE)

Committee Members:	Prof. Shing-Chi Cheung (Supervisor)
			Prof. Lei Chen
			Prof. Charles Zhang
			Prof. Mitchell Tseng (IELM)
			Prof. Michael Lyu (Comp. Sci. & Engg., CUHK)


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