While using large-scale Web Information Systems (WISs) customers sometimes get confused and experience difficulties in solving their business problems. We propose context modelling as a conceptual tool for aiding customers to regain the possibility of using the respective WIS efficiently. We integrate context modelling into the co-design methodology, identify some losing track patterns and propose respective customer aid. Finally we formalise our approach based on the theory of media types and the model of contextual information systems developed by Teodorakis et al.
The Web is evolving from an “eyeball web”, where cognitive processing of presented information is done by humans, into an “agent web” where such processing is fully automated, leaving man-system interaction only to a presentation layer. (In fact we could posit that the so-called Semantic Web would -strictly speaking of course- be wholly unnecessary if its users would be “merely” humans.)
Online purchase and delivery of goods and services requires an electronic contracting process. Formalization of contractual content enables automatic delivery of services and monitoring of the terms and conditions of the contract at service runtime. The Simple Obligation and Right Model (SORM) provides an abstract, domain-independent model of contractual content. Model instances can be interpreted and managed by applications involved in checking contractual entitlements and delivering and supervising a service in compliance with contractual rights and obligations. It captures the main types of rights and obligations and deals with their dynamics during the life-time of a contract.
This paper looks at how the use of ontologies to describe businesses and systems may allow a move away from standardization, as a basis for Enterprise Business Integration in favor of mediation between different standards. It proposes the Supply Chain Councils SCOR [1] model as a possible base for an ontology to describe businesses and systems. A workbench is described that would allow automatic configuration of orchestration systems to manage business to business and system to system integration. It also shows how the Semantic Web [2] could be used by agents to identify beneficial changes in a company's supply chain.
This paper describes a framework for flexible workflows based on events, states, and a new kind of process called a meta-workflow. Meta-workflows have five kinds of meta-activities and facilitate control over other workflows. We describe the framework and illustrate it with examples to show its features. The paper gives an architecture for incorporating it into existing workflows and also provides a formal semantics of execution. This framework can be used in web services, supply chains, and inter-organizational applications where coordination requirements are complex, and flexible and adaptable workflows are needed. It is also useful for handling, not just failure recovery, but also other kinds of exception situations, which arise frequently in web-based applications.
This paper proposes the concept of business events as the cornerstone to web service description and coordination. First, a web service architecture is introduced as the result of an event based analysis & design phase. Then, it is advocated how the event concept can be used for semantically rich web service description. A distinction is made between two web service interfaces: a non-transactional query interface and a transactional event notification interface. Furthermore, a web service composition model is proposed, based on event broadcasting and event preconditions, instead of traditional one-to-one method invocations. The composition model is presented in a static variant and in a version with dynamic subscription. Throughout the paper, it is shown how the event based approach fits entirely within the current standard SOAP/WSDL/UDDI web services stack.
The research community has begun an effort to investigate foundations for the next stage of the Web, called Semantic Web [1]. Current efforts include the Extensible Markup Language XML, the Resource description Framework, Topic Maps and the DARPA Agent Markup Language DAML+OIL. A rich domain that requires special attention is the semantics of geospatial information. In order to approach the Semantic Geospatial Web, a mediation system for querying spatial and non-spatial information is presented in this paper. The spatial information is represented in the Geographical Markup Language (GML). GML is an XML encoding developed by the Open-GIS Consortium for the transport and storage of spatial/geographic information, including both spatial features and non-spatial features. In order to integrate spatial information from several spatial XML documents (GML), we have based our work on the Community Web Portal concept with RDF and RQL, a declarative language to query both RDF descriptions,and related schemas.
Web Services hold the promise of a standards-based platform for automating the integration of applications over diverse networks, operating systems and programming languages. Reliable messaging is critical in this context; many enterprise systems require a messaging infrastructure that guarantees message delivery even in the presence of software and network failures. Using existing message-oriented middleware (MOM) for reliable Web services messaging seems natural. However, a variety of implementation challenges, including the support for specific reliable Web services messaging protocols, must be addressed. In this paper, we discuss the options for and implications of employing MOM to implement reliable messaging for Web services. In doing so, we contribute to the understanding of reliability for Web services in general.
To be able to monitor contracts at contract fulfillment stages is a key ingredient for a reliable, flexible, efficient, realistic and acceptable e-market. In this paper, we explore monitoring requirements of different e-market infrastructures, and define the monitorability of various e-market infrastructure approaches. For avoidance and anticipation of imminent contract violations, and detection and compensation of actual violations, a two-level framework is presented, a reference architecture of the two-level framework is demonstrated finally.
Traditional methodology for web application development can not fully satisfy the requirement raised by web services. Generally, distributed web applications are built on top of 3-tier client/server model, which is a relatively static environment that can provide reliable static service binding. However, in the web service-oriented environment, service binding is dynamic and just-in-time. How to enable the composition among the web services has become a key area in the software engineering research. In this paper, we present a new methodology for web application development, which is a framework that facilitates the visual design, validation and development of web service composition. The framework is mainly based on Web Service Composition Graph (WSCG), the underlying formalism for web service compositions. Using graph grammar and graph transformation defined on WSCG, the static topological structure of a web service composition can be described and the automation of the constructed web service composition is also facilitated.
In this paper we propose a foundational vision of e-Services, in which we distinguish between the external behavior of an e-Service as seen by clients, and the internal behavior as seen by a deployed application running the e-Service. Such behaviors are formally expressed as execution trees describing the interactions of the e-Service with its client and with other e-Services. Using these notions we formally define e-Service composition in a general way, without relying on any specific representation formalism.
The Web Service Offerings Language (WSOL) is a novel language for the formal specification of classes of service, various types of constraint, and management statements for Web Services. Compared with recent competing works, WSOL has several unique characteristics. One of them is a diverse set of reusability constructs: service offerings, constraint groups, constraint group templates, extension, inclusion, applicability domains, and operation calls. These constructs enable sharing parts of WSOL specifications between classes of service of different Web Services and development of libraries of reusable WSOL specifications. Consequently, they can help in alleviating heterogeneity of Web Services. In addition, reusability constructs are useful for easier development of new WSOL specifications from existing ones, for easier selection of Web Services and their classes of service, and for dynamic (run-time) adaptation of relationships between provider and consumer Web Services. Integration of WSOL reusability constructs into the works competing with WSOL would be beneficial.
The ability to rapidly locate useful on-line services (e.g. software applications, software components), as opposed to simply useful documents, is becoming increasingly critical in many domains. Current service retrieval technology is, however, notoriously prone to low precision. This paper describes a novel service retrieval approached based on the sophisticated use of process ontologies. Our preliminary evaluations suggest that this approach offers qualitatively higher retrieval precision than existing (keyword and table-based) approaches without sacrificing recall and computational tractability/scalability.
In this paper, we present the architecture of XRL/Flower. XRL/Flower is a software tool, which benefits from the fact that it is based on both XML and Petri nets. Standard XML tools can be deployed to parse, check, and handle XRL documents. The Petri-net representation allows for a straightforward and succinct implementation of the workflow engine. XRL constructs are automatically translated into Petri-net constructs. On the one hand, this allows for an efficient implementation. On the other hand, the system is easy to extend: For supporting a new routing primitive, only the translation to the Petrinet engine needs to be added and the engine itself does not need to change. Last, but not least, the Petri net representation can be analyzed using state-of-the-art analysis techniques and tools.
E-services are services that can be invoked over the Internet. One likely use of e-services would be to build business applications that can employ e-services from different service providers. This potential use of composite services in business settings highlights the issues of payment mechanisms, reliability, trust, inter-operability and service guarantees between different service providers. It also becomes essential to choose e-services that best fulfil the requirements of a particular business application. We investigate how patterns can be used in service composition to help in the development of business applications based on e-services.
We study the verification problem for e-service (and workflow) specifications, aiming at efficient techniques for guiding the construction of composite e-services to guarantee desired properties (e.g., deadlock avoidance, bounds on resource usage, response times). Based on e-service frameworks such as AZTEC and e-FLow, decision flow language Vortex, we introduce a very simple e-service model for our investigation of verification issues. We first show how three different model checking techniques are applied when the number of processes is limited to a predetermined number. We then introduce pid quantified constraint, a new symbolic representation that can encode infinite many system states, to verify systems with unbounded and dynamic process instantiations. We think that it is a versatile technique and more suitable for verification of e-service specifications. If this is combined with other techniques such as abstraction and widening, it is possible to solve a large category of interesting verification problems for e-services.
The Semantic Web uses formal distributed ontologies for representing relationships among concepts in the real world. A structured framework such as this allows agents to peruse and reason about published knowledge without the need for scrapers, information agents, and centralized ontologies. However, in order to process any information, an agent must be familiar with the underlying ontology used to markup that information. However, no single agent can be expected to be familiar with all possible ontologies that may be available on the Semantic Web. Therefore, translation services that transform concepts defined within previously unknown ontologies into known concepts allow agents to understand the available information and hence achieve their goal. This transformation may be achieved by invoking specific markup translation services or by logical reasoning through other shared ontologies. The RETSINA Calendar Agent (RCal) is a Distributed Meeting Scheduling Agent that processes schedules marked up on the Semantic Web, and imports them into the user's Personal Information Manager. Translation services, which are used to translate unknown concepts into known concepts, which are located using a DAML-S based service discovery mechanisms. In this paper, we present RCal, and demonstrate how it extracts and uses meaningful knowledge from the semantic markup. In addition, we describe how web-service discovery mechanisms are used when new concepts are encountered.
In an E-service environment, workflow involves not only a single organization but also a number of business partners. Therefore, workflow interoperability in such an environment is an important issue for enacting workflows. In this paper, we introduce our approach of using workflow views as a fundamental support for E-service workflow interoperability and for controlled (sub-) workflows visibility to external parties. We present a meta-model of workflow views and their semantics with example usage. We develop an interoperation model based on workflow views, with a supply-chain E-service cross-organization workflow example. We also propose an implementation of workflow view and cross-organizational interoperability based on contemporary Web service [14] technology, with respect to our E-ADOME workflow engine.
Ontologies are set to play a key role in the "Semantic Web", ' extending syntactic interoperability to semantic interoperability by providing a source of shared and precisely defined terms. DAML+OIL is an ontology language specifically designed for use on the Web; it exploits existing Web standards (XML and RDF), adding the familiar ontological primitives of object oriented and frame based systems, and the formal rigor of a very expressive description logic. The logical basis of the language means that reasoning services can be provided, both to support ontology design and to make DAML+OIL described Web resources more accessible to automated processes.
The ability to rapidly locate useful on-line services (e.g. software applications, software components, process models, or service organizations), as opposed to simply useful documents, is becoming increasingly critical in many domains. Current service retrieval technology is, however, notoriously prone to low precision. This paper describes a novel service retrieval approached based on the sophisticated use of process ontologies. Our preliminary evaluations suggest that this approach offers qualitatively higher retrieval precision than existing (keyword and table-based) approaches without sacrificing recall and computational tractability/scalability.
