Publications in 2002

Articles in Refereed Journals:

1. Menasce, D.A.. QoS Issues in Web Services. Internet Computing, IEEE, Vol. 6, Num. 6, pages 72-75, November/December 2002.
   Abstract: Quality of service (QoS) is a combination of several qualities or properties of a service, such as: availability is the percentage of time that a service is operating; security properties include the existence and type of authentication mechanisms the service offers, confidentiality and data integrity of messages exchanged, nonrepudiation of requests or messages, and resilience to denial-of-service attacks; response time is the time a service takes to respond to various types of requests; Response time is a function of load intensity, which can be measured in terms of arrival rates (such as requests per second) or number of concurrent requests. QoS takes into account not only the average response time, but also the percentile of the response time; and throughput is the rate at which a service can process requests. QoS measures can include the maximum throughput or a function that describes how throughput varies with load intensity. The QoS measure is observed by Web services users. These users are not human beings but programs that send requests for services to Web service providers. QoS issues in Web services have to be evaluated from the perspective of the providers of Web services and from the perspective of the users of these services.

Articles in Refereed Conferences:

1. Massimo Mecella, Francesco Parisi Presicce an Barbara Pernici. Modeling E -service Orchestration through Petri Nets . Technologies for E-Services, Lecture Notes in Computer Science, Vol. 2444, pages 109-134, Springer Verlag, July 2002.
   Abstract: B2B interaction requires new forms of coordination between participating organizations. Indeed, the main requirement is that the autonomy of each participating partner is preserved during the interaction, guaranteeing at the same time that the overall goals of the common process are reached. Mechanisms for regulating distributed workflow evolution when the workflow is composed of the invocation of E-services of different organizations are needed. The E-service orchestration model proposed in this paper provides a mechanism for supporting control of process evolution in terms both of control and data flows, and for distributing and assigning process responsibilities.

2. Srini Narayanan, Sheila A. McIlraith. Simulation, verification and automated composition of web services. WWW '02: Proceedings of the 11th international conference on World Wide Web, pages 77-88, ACM, 2002.
   Abstract: Web services - Web-accessible programs and devices - are a key application area for the Semantic Web. With the proliferation of Web services and the evolution towards the Semantic Web comes the opportunity to automate various Web services tasks. Our objective is to enable markup and automated reasoning technology to describe, simulate, compose, test, and verify compositions of Web services. We take as our starting point the DAML-S DAML+OIL ontology for describing the capabilities of Web services. We define the semantics for a relevant subset of DAML-S in terms of a first-order logical language. With the semantics in hand, we encode our service descriptions in a Petri Net formalism and provide decision procedures for Web service simulation, verification and composition. We also provide an analysis of the complexity of these tasks under different restrictions to the DAML-S composite services we can describe. Finally, we present an implementation of our analysis techniques. This implementation takes as input a DAML-S description of a Web service, automatically generates a Petri Net and performs the desired analysis. Such a tool has broad applicability both as a back end to existing manual Web service composition tools, and as a stand-alone tool for Web service developers.

3. Vladimir Tosic, Kruti Patel, Bernard Pagurek. WSOL - Web Service Offerings Language. CAiSE '02/ WES '02: Revised Papers from the International Workshop on Web Services, E-Business, and the Semantic Web, pages 57-67, Springer-Verlag, 2002.
   Abstract: WSOL (Web Service Offerings Language) is an XML (Extensible Markup Language) notation compatible with the WSDL (Web Services Description Language) standard. While WSDL is used for describing operations provided by Web Services, WSOL enables formal specification of multiple classes of service for one Web Service. A service offering is a formal representation of one class of service for a Web Service. As classes of service for Web Services are determined by combinations of various constraints, WSOL enables formal specification of functional constraints, some QoS (a.k.a., non-functional) constraints, simple access rights (for differentiation of service), price, and relationships with other service offerings of the same Web Service. Describing a Web Service in WSOL, in addition to WSDL, enables selection of a more appropriate Web Service and service offering for particular circumstances. Further, it supports dynamic adaptation and management of Web Service compositions using manipulation of service offerings.

Books and Monographs:

1. J. Cardoso. Quality of Service and Semantic Composition of Workflows. Ph.D. Thesis, University of Georgia, 2002.
   Abstract: Workflow management systems (WfMSs) have been used to support a variety of business processes. As organizations adopt new working models, such as e-commerce, new challenges arise for workflow systems. These challenges include support for the adequate management of quality of service (QoS) and the development of new solutions to facilitate the composition of workflow applications involving Web services. The good management of QoS directly impacts the success of organizations participating in e- commerce activities by better fulfilling customer expectations and achieving customer satisfaction. To enable adequate QoS management, research is required to develop mechanisms that specify, compute, monitor, and control the QoS of the products or services to be delivered. The composition of workflows to model e-service applications differs from the design of traditional workflows due to the number of Web services available during the composition process and to their heterogeneity. Two main problems need to be solved: how to efficiently discover Web services and how to facilitate their interoperability. To enhance WfMSs with QoS management, we have developed a QoS model that allows for the description of nonfunctional aspects of workflow components, from a quality of service perspective. To automatically compute the overall QoS of a workflow, we have developed a mathematical model and implemented an algorithm (SWR algorithm). Our QoS model and mathematical model have been validated with the deployment and execution of a set of production workflows in the area of genetics. The analysis of the collected data proves that our models provide a suitable framework for estimating, predicting, and analyzing the QoS of production workflows. To support, facilitate, and assist the composition of workflows involving Web services, we present a solution based on ontologies. We have developed an algorithm that workflow systems and discovery mechanisms can use to find Web services with desired interfaces and operational metrics, and to assist designers in resolving heterogeneity issues among Web services. Our approach provides an important solution to enhance Web service discovery and interoperability.

Publications in Refereed Workshops:

1. S. Nakajima. Model-Checking Verification for Reliable Web Service. OOPSLA Workshop on Object-Oriented Web Services, 2002.
   Abstract: Model-checking is a promising technique for the verification and validation of software systems. Web service, an emerging technology in the Internet, is an autonomous server that may offer an individual service. It sometimes requires to combine more than one to meet our requirements. WSFL(Web Services Flow Language) is proposed as a language to provide means to describe Web service aggregation. We are interested in how much the software model-checking technique can be used as a basis for raising reliability of Web service, Web service flow descriptions in particular. Our experience shows that faulty flow descriptions can be identified with the proposed method. The method is also very helpful in studying an alternative semantics of the WSFL in regard to the handling of dataflows.

Technical Reports and Manuals:

1. Akhil Sahai, Anna Durante, Vijay Machiraju. Towards Automated SLA Management for Web Services. Num. HPL-2001-310, HP Laboratories, July 2002.
   Abstract: In order to automate SLA management it is essential to specify SLAs in precise and unambiguous manner as well as keep the specification flexible. While precision will help automate the process of monitoring and metric collection, flexibility will enable extending it to unforeseen service level agreement specifications.

2. Anbazhagan Mani, Arun Nagarajan. Understanding quality of service for Web services. IBM, 2002.
   Abstract: With the widespread proliferation of Web services, quality of service (QoS) will become a significant factor in distinguishing the success of service providers. QoS determines the service usability and utility, both of which influence the popularity of the service. In this article, we look at the various Web service QoS requirements, bottlenecks affecting performance of Web services, approaches of providing service quality, transactional services, and a simple method of measuring response time of your Web services using the service proxy.