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P. Le Hégaret: Leading Web Services To Their Full Potential |
The World Wide Web was originally designed for people to share information. It now becomes, with the Web Services, a machine to machine interaction. A travel agent should be able to use the credit card company web service, as well as the one of the hotel or the airline. With the creation of the Web Services Activity in 2002, the W3C is now working on the architecture of Web Services, as well as XML protocols and web services description, under the W3C Royalty-Free terms. While reconciling the current goals of Web Services (mainly for XML-based RPC) and the Web Architecture (URI, HTTP GET, ...), the W3C is also working on a long term vision with its Semantic Web activity. In the meantime, routing, reliable messages, choreography or privacy of web services still need to be addressed.
S. Robak, and B. Franczyk: Modeling Web Services Variability with Feature Diagrams |
In the paper the proposal for modeling flexibility of the Web Services with feature diagrams is introduced. Feature diagrams allow presenting the commonality and above all variability of described concept. In the paper the classification of Web Services features from the users' point of view is given. The comparison of Web Services with the orthogonal component concept is also discussed.
U. Topp, P. Müller, J. Konnertz, and A. Pick: Web based services for embedded devices |
Field devices are becoming more and more 'intelligent'. This report describes how one can use this in conjunction with approved and upcoming internet technologies and standards to overcome many problems arising due to the fact that every manufacturer has at least one way to communicate to his devices. The presented case study utilizes two approaches: One is an embedded web server with CGI capability, the other is an embedded application of the SOAP protocol.
W.-J. van den Heuvel, and S. Artyshchev: Developing A Three-Dimensional Transaction Model for Supporting Atomicity Spheres |
Web Services (WSs) are touted as a new promising paradigm for developing and
deploying distributed, Internet-based business applications. Recently, we have witnessed the
emergence of web-service description and request languages as well as composition protocols.
Typically, the service composition protocols tend to provide minimal support for transaction
management in order to implement reliable and robust web-based business transactions with
cohesive web-services. This support basically mimics some of the ACID-properties, apparently in
an implicit and arbitrary way.
In conclusion, sound theoretical underpinnings for incorporating transactional acidity in webservice
composition languages is currently lacking. This paper outlines a theoretical threedimensional
framework for acid criteria of e-business transactions. This framework serves as the
foundation of a transaction model that relies on "traditional" atomicity spheres.
P. F. Pires, and M. R. F. Benevides, and M. Mattoso: Building Reliable Web Services Compositions |
The recent evolution of internet technologies, mainly guided by the Extensible Markup Language (XML) and its related technologies, are extending the role of the World Wide Web from information interaction to service interaction. This next wave of the internet era is being driven by a concept named Web services. The Web services technology provides the underpinning to a new business opportunity, i.e., the possibility of providing value-added Web services. However, the building of value-added services on this new environment is not a trivial task. Due to the many singularities of the Web service environment, such as the inherent structural and behavioral heterogeneity of Web services, as well as their strict autonomy, it is not possible to rely on the current models and solutions to build and coordinate compositions of Web services. In this paper, we present a framework for building reliable Web service compositions on top of heterogeneous and autonomous Web services.
R. Tolksdorf: A Dependency Markup Language for Web Services |
Current mechanisms for the description of Web Services and their composition are either to coarse – by specifying a functional interface only – or too fine – by specifying a concrete control flow amongst services. We argue that more adequate specifications can be built on the notion of dependency of activities and coordination activities to manage these dependencies. We propose a Dependency Markup Language to capture dependencies amongst activities and generalizations/specializations amongst processes. With that, we can describe composite services at more suited levels of abstraction and have several options to use such descriptions for service coordination, service discovery and service classification.
S. Overhage, and P. Thomas: On Specifying Web Services Using UDDI Improvements |
Web services are interoperable components that can be used in application integration and component-based application development. In so doing, the appropriate specification of Web services as the basis for discovery and configuration becomes a critical success factor. This paper analyses the UDDI specification framework, which is part of the emerging Web service architecture, and proposes a variety of improvements referring to the provided information and appropriate formal notations. The resulting framework, called WS-Specification, provides different perspectives on Web services and holds additional information on the security, performance, implemented concepts and processes, coordination, interface definitions, and assertions. It maintains backward-compatibility and is ordered using a thematic grouping that consists of white, yellow, blue, and green pages.
M. Jeckle, and B. Zengler: Active UDDI -- An Extension to UDDI to Allow Dynamic and Fault Tolerant Service Invocation |
UDDI, Universal Description, Discovery, and Integration,
represents a directory for the publication and querying of
categorized Web services. Publication and query are performed by
utilizing UDDI's Application programming interface (API), which
employs SOAP as a communication instrument.
By offering an invocation API in addition to two other types for
examination, UDDI allows clients to search for and subsequently
invoke specific Web services. Failures in invoking already sought
and, on the application side, statically cached Web
services typically result in re-querying the registry.
However, an application's reaction time in response to changes is
limited due to UDDI's replication latency, i.e. the amount of time
it takes for changes to entries stored inside the UDDI repository
to be propagated to all UDDI nodes.
This paper proposes a mechanism termed active UDDI, which
allows the extension of UDDI's invocation API in order to enable
fault-tolerant and dynamic service invocation.
B. Kalali, P. Alencar, and D. Cowan: Notification Service Provider Framework |
In this paper we extend current typical Web service architectures by providing a Web Service Notification Framework (WSNF). Besides the three standard roles found in current frameworks (i.e., the service provider, the service requestor, and the service registry), our approach introduces an additional role that we call the service notifier. The framework is designed in four layers: the Proxy Layer, the Web Server Layer, the Application Notification Server Layer, and the Application Worker Layer. Since the WSNF itself is a service provider, this framework is reflective in the sense that it checks and notifies itself about changes. The framework is documented using design patterns. The set of patterns applied in the framework design includes the following patterns: the singleton, the delegation, the factory method, the observer, the mediator, the notifier, which is a combination of the mediator and the observer, the item description, and the proxy. The notifier pattern is in fact a publisher-subscribe pattern with push semantics. The framework uses a requestor profile to support notifications related to a category of events related to changes, failures, and version control problems of Web services.
M. Montebello, and C. Abela: DAML enabled Web Services and Agents in the Semantic Web |
Academic and industrial bodies are considering the issue of Web Services as being the next step forward. A number of efforts have been made and are evolving to define specifications and architectures for the spreading of this new breed of web applications. One such work revolves around the Semantic Web. Lead researches are trying to combine the semantic advantages that a Semantic Web can provide to Web Services. The research started with the now standardized RDF (Resource Description Framework) and continued with the creation of DAML+OIL (DARPA Agent Markup Language and Ontology Inference Layer) and its branches, particularly DAML-S (where S stands for Services).
The Semantic Web's point of view, being considered in this paper presents a rich environment where the advantages of incorporating semantics in searching for Web Services can be fully expressed. This paper aims to describe an environment called DASD (DAML Agents for Service Discovery) where Web Service requesters and providers can discover each other with the intermediary action of a Matchmaking service
Z. Hu: Using Ontology to bind Web Services to the Data Model of Automation Systems |
Supplying integrated data model with multiple structures for addressing diverse requirements from different production lifecycles and control levels is the natural development of automation systems. Data processing, presentation and manipulation require well-designed computation model that consists of interrelated groups of function components or applications that can be realized in the form of web services. Binding the available web services to the designed data model becomes a challenging task if a great amount of web services is confronted. In this paper we will use ontology technology to address the binding problem. We will present the required ontology model including the formal expression of ontology, object model, mapping to XML representation and the corresponding system architecture for binding web services.
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