JWSR, Volume 2, Number 4, October-December 2005
Official Publication of the Information Resources Management Association
Published: Quarterly in Print and Electronically

Editor-In-Chief: Liang-Jie Zhang, IBM, USA

EDITORIAL PREFACE:

"The Lifecycle of Services Computing Innovations"
Liang-Jie Zhang, IBM T.J. Watson Research Center, USA

RESEARCH PAPERS

PAPER ONE:

"NAM: A Network Adaptable Middleware to Enhance Response Time of Web Services" (pp. 1-21)

Ghandeharizadeh, S.; Papadopoulos, C.; Cai, M.; Zhou, R. & Pol, P.
University of Southern California, USA

Web Services is an emerging software technology that is based on the concept of software and data as a service. Binary and XML are two popular encoding/decoding mechanisms for network messages. A Web Service may employ a loss-less compression technique (e.g., Zip, XMill, etc.) in order to reduce message size prior to its transmission across the network, minimizing its transmission time. This saving might be outweighed by the overhead of compressing the output of a Web Service at a server and decompressing it at a client. The primary contribution of this paper is NAM, a middleware that strikes a compromise between these two factors in order to enhance response time. NAM decides when to compress data, based on the available client and server processor speeds and network characteristics. When compared with today’s common practice to transmit the output of a Web Service uncompressed always, our experimental results show NAM either provides similar or significantly improved response times (at times, more than 90% improvement) with Internet connections that offer bandwidths ranging from 80 to 100 Mbps.

PAPER TWO:

"On Feature Interactions Among Web Services" (pp. 22-47)

Weiss, M. & Esfandiari, B.
Carleton University, Canada

Web Services promise to allow businesses to adapt rapidly to changes in the business environment and to the needs of customers. However, the rapid introduction of new services paired with the dynamicity of the business environment also leads to undesirable interactions that negatively impact service quality and user satisfaction. In this paper, we propose an approach for modeling such undesirable interactions as feature interactions. As each functional feature ultimately is motivated by non-functional requirements, we make an explicit distinction between functional and non-functional features. We then describe our approach for detecting and resolving feature interactions among Web Services. The approach is based on goal-oriented analysis and scenario modeling. It allows us to reason about feature interactions in terms of goal conflicts and feature deployment. Three case studies illustrate the approach. The paper concludes with a discussion of our findings and an outlook on future research.

PAPER THREE:

"AND/OR Graph and Search Algorithm for Discovering Composite Web Services" (pp. 48-67)

Liang, Q.A., Singapore Management University, Singapore
Su, S.Y.W., University of Florida, USA

This paper presents a formalization of the Web Service composition problem as a search problem in an AND/OR graph, and a search algorithm for searching the graph to identify composite service(s) that satisfies a Web Service request. Given a service request that can only be satisfied by a composition of Web Services, we identify the service categories that are relevant to the request and dynamically construct an AND/OR graph to capture the input/output dependencies among the Web Services of these service categories. The graph is modified, based on the information provided in the service request. The search algorithm is then used to search the modified AND/OR graph for a minimal and complete composite service template that satisfies the service request. The algorithm can be applied repeatedly to the graph to search for alternative templates until the result is approved by the service requester. We have evaluated the algorithm both analytically and experimentally, and the experiment results are presented.

PAPER FOUR:

"Realizability of Conversation Protocols with Message Contents" (pp. 68-93)

Fu, X., Georgia Southwestern State University, USA
Bultan, T. & Su, J., University of California, Santa Barbara, USA

A promising way to model the global behavior of a Web Service composition is to characterize the set of conversations among the participating Web Services. A conversation protocol specifies the desired global behaviors of a Web Service composition. The realizability problem is to decide whether, given a conversation protocol, a Web Service composition can be synthesized that generates exactly the same set of conversations specified by the protocol. This is a key problem in the top-down specification of the Web Service compositions. In our earlier work, we developed sufficient conditions for realizability of conversation protocols based on a model that abstracts the contents of the messages. The present paper extends our earlier work by allowing message contents to be used in the realizability analysis. We show that taking the message contents into account yields more accurate analysis. To overcome the state-space explosion caused by the message contents, we propose symbolic analysis techniques for the realizability conditions. In addition, we show that the analysis of one of the realizability conditions ? the autonomy condition ? can be done using an iterative refinement approach.

PAPER FIVE:

"Authorization Service for Web Services and its Application in a Health Care Domain" (pp. 94-119)

Indrakanti, S., Varadharajan, V. & Hitchens, M.
Macquarie University, Australia

In this paper, we discuss the design issues for an authorization framework for Web Services. In particular, we describe the features required for an authorization policy language for Web Services. We briefly introduce the authorization service provided by Microsoft .NET MyServices and describe our extended authorization model that proposes extensions to the .NET MyServices authorization service to support a range of authorization policies required in commercial systems. We discuss the application of the extended authorization model to a health care system built using Web Services. We use the XML Access Control Language (XACL) in our implementation to demonstrate our extended authorization model. This also enables us to evaluate the range of authorization policies that XACL supports.

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For full copies of the above articles, check for this issue of the International Journal of Web Services Research (JWSR) in your Institution's library.
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