Emerging Web Services Technology

In former days Tim Berners-Lee proposed a soon breakthrough of the Semantic Web. As a breakthrough he considered every second web page to be connected to an ontology. In the mean time we have seen a lot of applications of semantic technologies, like semantic web services, semantic information integration, and ontology based search for documents. However it seems also clear that the forecast of TBL did not (yet) arrive. While in the last years there has always been great academic interest in Semantic Web and in semantic technologies and even first industrial products appeared, we did not see the industrial breakthrough of Semantic Web technologies. On the other hand there was a strong increasing interest in other trends like SOA architectures, Web 2.0 etc. which ruled out Semantic Web in publicity and in connected activities like new product developments, foundations of new companies, and money involved. The question arises what are the reasons for that and which of these newer trends could have an influence on the further development of semantic technologies. While so far the Semantic Web was driven to a large extent from the academic side, its future acceptance and relevance to the industrial world heavily depends on whether the future development of Semantic Web technologies is influenced by industry needs rather than pure academic ones. This becomes essential and will decide whether semantic technologies are considered as relevant technology and will be used in future industrial applications and products. In actual industry applications, it was proved that the combination of trendy topics like SOA and Web 2.0 with intelligent features of semantic technologies generates large impact for the industrial and business world and thereof - the breakthrough of the Corporate Semantic Web.

Web Services have become the de-facto standard for architecting and implementing business collaborations within and across organization boundaries. Web service composition refers to the creation of new (Web) services by combining the functionalities provided by existing ones. A process-oriented language for service composition has been proposed as BPEL4WS. BPEL4WS specification defines an XML based formal language and provides a general overview of the framework. However no design and implementation issues are described in it. Most of the available BPEL4WS compliant process engines are heavy weight, complex and not extensible. This paper describes the design and implementation of an embeddable, scalable and extensible BPEL4WS compliant process engine. This paper highlights the concepts and strategies that were followed during the design and implementation. Primary contribution of this paper is the design of stateless process model and the design of run time core engine using a multi-processor scheduler.

An increasing amount of applications are currently built as Web Service compositions based on the TCP/IP+HTTP protocol stack. In case of any deviations from desired runtime-behavior, problematic Web Services have to be substituted and their execution plans have to be updated accordingly. One challenge is to detect deviations as early as possible allowing timely adaption of execution plans. We advocate a cross-layer approach to detect bad performance and service interruptions much earlier than by waiting for their propagation through the full protocol stack. This position paper describes an approach to gain detailed real-time information about Web Service behavior and performance based on a cross-layer analysis of the TCP/IP+HTTP protocols. In this paper we focus especially on TCP. The results are used to make decisions supporting service selection and replanning in service-oriented computing scenarios. Furthermore, generic architectural components are proposed implementing the functionality needed which can be used in different web-based scenarios.

Service Level Agreements (SLAs) are commonly prepared and signed agreements that form the contracts between a service provider and its customers, defining the obligations and liabilities of the parties. Naturally, SLAs should reflect the business needs of both customer and supplier. SLAs are usually formed through either the adoption of a boilerplate agreement from the provider, or through a mediation/negotiation process between the parties. With the increasing adoption of software supply being implemented as a network service, such schemes are rigid or slow and costly, This paper proposes a system that the parties can use to facilitate both fast and flexible agreements. It proposes automation of SLA creation from a set of Service Level Objectives (SLOs), making use of software agents and adopting a social order function by incorporating it into the decision process.

In order for service-oriented architectures (SOAs) to deliver their true value for the business, e.g. flexibility and transparency, a holistic service management needs to be set up in the enterprise. To perform all the service management tasks efficiently heavy support by automated processes and tools is necessary. This article describes a service description approach that is based on OWL-S (Web Ontology Language for Services) and focuses on nonfunctional criteria. It starts with the necessary service management tasks and explains non-functional data elements and statements for its automated support. After covering related work it explains the proposed flexible extension to OWL-S. This extension is twofold. Firstly, simple service lifecycle elements are added using the normal extension mechanism. Secondly for adding QoS (Quality of Service) capabilities, the approach combines this extension mechanism with UML (Unified Modeling Language) Profile for QoS. A prototype delivers the proof-of-concept.

The development of composite Web Services is being specified in a more declarative way than imperative programming. In this context, conceptual modeling has been the most accepted solution. Conceptual modeling of Web services has been done using behavioral models (like activity diagrams) considering mainly the dynamic view. We believe that, besides the dynamic aspects, the models should capture structural requirements between web service operations. In this way, behavioral models could be complemented with a structural model. In this paper we introduce a Web service composition modeling solution, following the MDA approach, considering both -structural and dynamic properties-enriched with semantic constraints in order to automatically generate composite Web services implemented in BPEL.

The design of Web Services is nowadays emerging as one of the most important tasks in the development of a Service Oriented Application. Web service designers need some guidelines to achieve a design of quality. In this paper we provide a methodological guide in the context of a Web engineering method called OOWS. Our approach allows identifying the operations of Web services following a model driven approach, taking the OO-Method / OOWS conceptual models as the source. To document our approach, we apply our ideas to a real case study of a Web application to manage University Research Groups.

Web service discovery given a user request becomes a fundamental challenge in a service-oriented world. The overall success of Service Oriented Architectures (SOA) however will very much depend on automatic and accurate solutions for the discovery problem. Furthermore such solutions need to be efficiently integrated with other service related tasks (e.g. service composition). In this paper we propose a logic based approach for service discovery with composition support. First, we provide a formal model for service discovery based on semantic description of services and then we show how such an approach can be integrated with service composition. Furthermore we provide a prototype implementation that validates our theoretical solution.

Making mobile phones capable of consuming Web services over wireless networks is a challenging task because of the different issues to be addressed and the limited resources of mobile devices. In this paper, we focus on the issue of how to perform dynamic discovery and invocation of Web services from mobile phones when a J2ME wireless middleware is used. In order to solve the limitations of the middleware platform when mobile phones act as Web services requestor we propose a Web service based dynamic proxy between service providers and mobile consumers. With this approach, we provide the following features to mobile devices: (1) support of dynamic binding, (2) support of UDDI specification, (3) support of SOAP messages with encoded representation and (4) handling of complex data types. The paper includes the description of the dynamic proxy, implementation and experimental results with the performance of the approach proposed.

This paper presents a suite of software code metrics, developed specifically for service-oriented systems with a well-defined methodology, which can be used as indicators of runtime efficiency. Existing literature on software metrics is mainly focused on centralized systems, while work in the area of distributed systems, particularly in service-oriented systems, is scarce. Firstly, a critical analysis of the problem domain identifies a number of software attributes which are likely to have an impact on efficiency. Secondly, concrete metrics are defined and evaluated (theoretically and empirically) for all identified attributes, with results showing that these software metrics are strongly correlated to typical efficiency metrics. Finally, a simple algorithm, which facilitates the runtime adaptation of service-oriented systems via service redeployment, illustrates a practical application of the metrics.

Web Services are the fitted technical solution which provides the required loose coupling to achieve Service Oriented Architecture (SOA). However, there is still much to be done in order to increase flexibility and adaptability to SOA-based applications. In previous researches, we proposed approaches based on Aspect Oriented Programming (AOP) and Process Algebra (PA) to address flexibility and client generation issues in the Web Service context. In this paper, we extend these works in order to automatically create extended BPEL processes and generate clients which dynamically adapt themselves to the service changing.

There is a three-fold argument that there are too many overlapping Web service standards, they are not constraining enough and they exhibit too much proprietary interest. These criticisms suggest a dilemma of whether Web service standards are worth investing time in — which raises the question of whether we should use standards or not. This dichotomy raises issues critical to both software engineering and business. Deciding which standards to adhere to is difficult from the viewpoints of the software developer and the perspective of the business arm. We discuss standards’ benefits and downfalls, looking at the implications for stakeholders. For successful uptake standards need precision and flexibility in solutions to common development challenges. Whether there are enough rigorous standards, or whether there are not sufficient robust standards is at the heart of the matter. We will expose different facets of an argument pointing to a standards marshalling framework for easier adherence.