Showing papers on "Differentiated service published in 2007"

Reputation-Enhanced QoS-based Web Services Discovery

Abstract: With an increasing number of Web services providing similar functionalities, quality of service (QoS) is becoming an important criterion for selection of the best available service. Currently the problem is twofold. The Universal Description, Discovery and Integration (UDDI) registries do not have the ability to publish the QoS information, and the authenticity of the advertised QoS information available elsewhere may be questionable. We propose a model of reputation-enhanced QoS- based Web services discovery that combines an augmented UDDI registry to publish the QoS information and a reputation manager to assign reputation scores to the services based on customer feedback of their performance. A discovery agent facilitates QoS-based service discovery using the reputation scores in a service matching, ranking and selection algorithm. The novelty of our model lies in its simplicity and in its coordination of the above mentioned components. We present experiments to evaluate the effectiveness of our approach using a prototype implementation of the model.

Preference-based selection of highly configurable web services

Abstract: A key challenge for dynamic Web service selection is that Web services are typically highly configurable and service requesters often have dynamic preferences on service configurations. Current approaches, such as WS-Agreement, describe Web services by enumerating the various possible service configurations, an inefficient approach when dealing with numerous service attributes with large value spaces. We model Web service configurations and associated prices and preferences more compactly using utility function policies, which also allows us to draw from multi-attribute decision theory methods to develop an algorithm for optimal service selection. In this paper, we present an OWL ontology for the specification of configurable Web service offers and requests, and a flexible and extensible framework for optimal service selection that combines declarative logic-based matching rules with optimization methods, such as linear programming. Assuming additive price/preference functions, experimental results indicate that our algorithm introduces an overhead of only around 2 sec.~compared to random service selection, while giving optimal results. The overhead, as percentage of total time, decreases as the number of offers and configurations increase.

Flow-Based Service Selection forWeb Service Composition Supporting Multiple QoS Classes

Abstract: In the service oriented paradigm applications are created as a composition of independently developed Web services. Since the same service may be offered by different providers with different non-functional Quality of Service (QoS) attributes, a selection process is needed to identify the constituent services for a given composite service that best meet the users QoS requirements. In this paper, we consider a broker that offers a composite service with multiple QoS classes to several users each generating a flow of requests over time. We propose a service selection scheme which optimizes the end-to-end aggregated QoS of all incoming flows of requests by means of a simple linear programming problem which scales as the number of users, request volumes and/or services grows. This approach differs from most of the current proposals which may not scale well since: a) requests, even from the same user, are handled independently from one another; and b) the selection process often requires the solution of an NP-hard problem.

Context-based matching for Web service composition

Abstract: In this paper, we propose a novel matching framework for Web service composition. The framework combines the concepts of Web service, context, and ontology. We adopt a broad definition of context for Web services, encompassing all information needed for enabling interactions between clients and providers. Context-based matching for Web services requires dealing with three major research thrusts: context categorization, modeling, and matching. We first propose an ontology-based categorization of contextual information in Web service environments. We then define a two-level mechanism for modeling Web service contexts. In the first level, service providers create context specifications using category-specific Web service languages and standards. In the second level, context specifications are enveloped by policies (called context policies) using WS-Policy standard. Finally, we present a peer-to-peer architecture for matching context policies. The architecture relies on a context matching engine, context policy assistants, and context community services. Community services implement rule-based techniques for comparing context policies.

Combining subjective and objective QoS factors for personalized web service selection

Abstract: Web service is an emerging Internet technology to dynamically describe, discover and communicate. According to the Web Service Architecture (WSA) published by W3C, users can find services through the repository Universal Description, Discovery and Integration (UDDI). However, the UDDI may find many web services with similar functions without considering the nonfunctional quality of service (QoS) information. Under such circumstances, users may have difficulty deciding which service is suitable. This paper proposes a fuzzy-based UDDI with QoS support. Unlike many similar researches, the proposed method tries to consider not only the objective factors described by service providers but also the subjective information with trustability evaluations from users who use those services. Genetic algorithm (GA) is adapted to learn user preferences, and fuzzy logic is applied for making decisions. With a fuzzy query interface to input subjective and objective factors, users can determine the most suitable web service for personal use.

Integration of IT service management into enterprise architecture

Abstract: Enterprise architecture supports organizational engineering in many ways. Service orientation is regarded as dominant operations model for service providers -- within and beyond IT. As a consequence, it is important to integrate service management and service orientation into enterprise architecture. This paper proposes an enterprise architecture extension that achieves such an integration. IT service management is defined according to ITIL. Based on the integration of service management into enterprise architecture, the integration of Service Oriented Architecture is discussed as a further extension. The research is based on the Business Engineering approach and the guidelines of Method Engineering.

DIANE: an integrated approach to automated service discovery, matchmaking and composition

Abstract: Automated matching of semantic service descriptions is the key to automatic service discovery and binding. But when trying to find a match for a certain request it may often happen, that the request cannot be serviced by a single offer but could be handled by combining existing offers. In this case automatic service composition is needed. Although automatic composition is an active field of research it is mainly viewed as a planning problem and treated separatedly from service discovery. In this paper we argue that an integrated approach to the problem is better than seperating these issues as is usually done. We propose an approach that integrates service composition into service discovery and matchmaking to match service requests that ask for multiple connected effects, discuss general issues involved in describing and matching such services and present an efficient algorithm implementing our ideas.

Battery-efficient generic advertising service for wireless mobile devices

Abstract: In one embodiment, a method for acquiring service provider information includes querying a wireless network for service provider information, receiving an advertisement response containing advertising service scheduling information, and configuring a power conservation mode responsive to the advertising service scheduling information.

Considering suppressed packets improves buffer management in QoS switches

Abstract: The following buffer management problem arises in network switches providing differentiated services: At the beginning of each time step, one packet can be sent, and afterwards an arbitrary number of new packets arrive. Packets that are not sent can be stored in a buffer. Each packet is attributed by a deadline, and a packet is automatically deleted from the buffer if it is still stored in the buffer by the end of its deadline. The differentiated service model is abstracted by attributing each packet with a value according to its service level. A buffer management strategy determines the packet to be sent in each time step. The goal of a buffer management strategy is to maximize the sum of the values of sent packets.We introduce the concept of suppressed packets and present a deterministic strategy that is based on this concept. We show that this strategy achieves a competitive ratio of 2√2--1 a 1.828, which is the best known competitive ratio in the deterministic case. Further, we present a memoryless version of this strategy that achieves a competitive ratio of a 1.893. This is the first memoryless strategy that achieves a competitive ratio less than 2, and the competitive ratio of this strategy is even better than the ratios of all previously known deterministic strategies. This demonstrates the potential of the concept of suppressed packets. In addition, we present a simple strategy that achieves the optimal competitive ratio of min{(1 + α)/α, 2α/(α+1)} ≤ √2, if only two packet values 1 and α > 1 are possible.

Channel-Aware Scheduling for QoS and Fairness Provisioning in IEEE 802.16/WiMAX Broadband Wireless Access Systems

Abstract: In the last few years, standardization activities within the IEEE 802.16 Working Group have resulted in the publication of specifications for an air interface of Fixed broadband wireless access systems. WiMAX is the commercial name of products compliant with the approved IEEE 802.16 standard. Although the standard suggests the main principles in designing a QoS architecture to support multimedia broadband services, implementation details are left to manufacturers. This article addresses a channel-aware scheduling algorithm conceived for a point-to-multipoint WiMAX architecture. It aims at enabling downlink traffic delivery with differentiated service treatment, even in nonideal channel conditions. A technique to compensate for channel errors is proposed to preserve QoS and fairness of a WF2Q+ based scheduling algorithm. The performance behavior of the proposed algorithm is confirmed by the outputs of a comprehensive simulation campaign.

A stakeholder-driven service life cycle model for SOA

Abstract: Service-orientation is a relatively new paradigm aiming at developing software systems that are adaptive and dynamic. Service-oriented systems are developed by composing services that are shared across organizations. Because new roles and new development tasks are introduced in service-oriented development as opposed to traditional software engineering, a new approach to service life cycle management is required. In this paper, based on the observations of the state of the art in the field, we propose a stakeholder-driven service life cycle model for service oriented architecture (SOA). Horizontally, the model shows the activities that associated with the stakeholders in SOA. While vertically, the model shows the interactions and cooperation between the stakeholders. This model facilitates the researchers to gain further insight into service-oriented development and governance.

Towards a theory of web service choreographies

Abstract: A fundamental promise of service oriented architecture (SOA) lies in the ease of integrating sharable information, processes, and other resources through interactions among the shared components that are modeled as web services. It is expected that not only the participating services are complex and have observable states, but the number of interacting services may be also large. Prior work on choreographies (conversation protocols) all focuses on specifying how the interacting web services should behave globally. Studies have shown that the relationships between global and local specifications of service interactions could be rather intricate. In this paper, we formulate a framework consisting of logical and implementation levels. We survey and discuss the technical problems and known results concerning service design, analysis and verification in this framework.

A new call admission control method for providing desired throughput and delay performance in IEEE802.11e wireless LANs

Abstract: The draft IEEE 802.11e standard aims at providing quality of service (QoS) support in 802.11 wireless local area networks (WLANs). Enhanced distributed coordination function (EDCF), being the fundamental medium access control mechanism in IEEE 802.11e, can only provide service differentiation but offers no QoS guarantees. While service differentiation does not perform well under high traffic load conditions, call admission control (CAC) becomes necessary in order to provide and support the QoS of existing calls. In this paper, we first analyze the saturation throughput and mean access delay performance of differentiated service provided by EDCF. Specifically, we investigate the impact of transmission opportunity (TXOP) and wireless channel errors on the performance of the EDCF. Based on the results from this analysis, we propose a new CAC algorithm that provides the desired throughput and access delay performance. Simulated performance results demonstrate the effectiveness of the proposed CAC algorithm

Search-based testing of service level agreements

Abstract: The diffusion of service oriented architectures introduces the need for novel testing approaches. On the one side, testing must be able to identify failures in the functionality provided by service. On the other side, it needs to identify cases in which the Service Level Agreement (SLA) negotiated between the service provider and the service consumer is not met. This would allow the developer to improve service performances, where needed, and the provider to avoid promising Quality of Service (QoS) levels that cannot be guaranteed. This paper proposes the use of Genetic Algorithms to generate inputs and configurations for service-oriented systems that cause SLA violations. The approach has been implemented in a tool and applied to an audio processing workflow and to a service for chart generation. In both cases, the approach was able to produce test data able to violate some QoS constraints.

System and method for managing domain policy for interconnected communication networks

Abstract: The present invention is directed to a system and method for managing domain policy for interconnected communication networks. The present invention governs communication service policy for interconnection among remote communication services to allow users to communicate with other users in remote domains. Exemplary embodiments allow the local communication services to guarantee certain service aspects even when remote domains are involved. For example, the local service enablers can assert their local service policy across domains. A local service enabler can choose other service enablers in remote domains based on specific criteria that meets the local service enabler's settings and user preferences. The local service enabler can protect itself from connection to other service enablers that may contradict its local settings. Thus, the present invention can manage communication services across remote domains, while each domain can continue to be managed locally according to the needs and preferences of the local users.

Service-oriented architecture and methods for direct invocation of services utilizing a service requestor invocation framework

Abstract: A data processing system implementing a service-oriented architecture that efficiently provides for self-directed communications between service requesters and service providers. Service providers, operative to implement a predefined computing functions, are responsive to first service requests and operative to provide a first service responses. Service requesters executed remote from service providers are operative to provide second service requests and receive second service responses. A service invocation framework local to each service requester functions to convert between first and second service requests and first and second service responses and to establish direct invocation communications connection with a selected service provider for the exchange of first service requests responses. A service invocation manager provides configuration meta-data, upon dynamic request by a service invocation framework, to define the conversions and communications connection to be implemented by the service invocation framework with respect to a service provider.

System and method for supporting service networks in a service-oriented architecture environment

Abstract: A system and method for supporting Service Networks in a SOA environment. In accordance with an embodiment, the principles governing the topology of computer networks can be similarly applied to the service space from small federated Service Segments (or sub domains), to large public federated Service Domains. At the heart of the Service Network are one or more Service Routers, that are themselves responsible for transparently bridging between federated Service Segments. The Service Routers determine where services reside in the Service Network and, based on routing information gathered through interaction with other Service Routers, Network Routers and other mechanisms, deliver service requests, using optimal routes, from a source Service Segment to the target Service Segment. Working in concert with the Service Router, an Enterprise Service Bus (ESB) can abstract the location of services, and hide the existence of the Service Network from service requestors.

A network pricing game for selfish traffic

Abstract: The success of the Internet is remarkable in light of the decentralized manner in which it is designed and operated. Unlike small scale networks, the Internet is built and controlled by a large number of disparate service providers who are not interested in any global optimization. Instead, providers simply seek to maximize their own profit by charging users for access to their service. Users themselves also behave selfishly, optimizing over price and quality of service. Game theory provides a natural framework for the study of such a situation. However, recent work in this area tends to focus on either the service providers or the network users, but not both. This paper introduces a new model for exploring the interaction of these two elements, in which network managers compete for users via prices and the quality of service provided. We study the extent to which competition between service providers hurts the overall social utility of the system.

On ISOA: intentional services oriented architecture

Abstract: Despite the growing acceptance of SOA, service-oriented computing remains a computing mechanism to speed-up the design of software applications by assembling ready-made services. We argue that it is difficult for business people to fully benefit of the SOA if it remains at the software level. The paper proposes a move towards a description of services in business terms, i.e. intentions and strategies to achieve them and to organize their publication, search and composition on the basis of these descriptions. In this way, it leverages on the SOA to an intentional level, the ISOA. We present ISM, the model to describe intentional services, and to populate the service registry. We highlight its intention driven perspective for service description, retrieval and composition. Thereafter, we propose a methodology to determine intentional services that meet business goals. Finally, we introduce agent architecture to support model driven execution of intentional services.

A Variability Modeling Method for Adaptable Services in Service-Oriented Computing

Abstract: Publish-discover-compose paradigm of service-oriented computing (SOC) presents a challenge on service applicability. Services are not just for predefined clients, rather for potentially many unknown clients. Hence, published services should be highly adaptable to various service clients and contexts. For that, service variability must carefully be modeled by considering the unique computing paradigm and requirements of SOC such as dynamic discovery and composition of services. Current SOC approaches to modeling services largely focus on defining business processes and service components without considering service variability in sufficient details. In this paper, we first compare the variability on conventional applications and the variability on SOC. Then, we identify four types of variability on services. For the types of service variability, we present a method to model service variability and design adaptable services. Using our proposed framework, we believe the applicability and reusability of such services can be greatly increased.

Network service version management

Abstract: Network service version management techniques are disclosed. Service access information, which is associated with access to a network service by a network service user, may be destined for a particular version of the network service. A determination is made as to whether a different version of the network service is accessible by the network service user. If so, then a further determination is made as to whether to select the different version of the network service to process the service access information. Any inconsistency between versions of the network service, such as different information requirements, can be handled by transforming received service access information. A replay function may also be provided, to have service access information again processed by the same or a different version of a network service. This function may be useful, for example, where a version of a service is rolled back or for debugging.

Using a model-driven transformational approach and service-oriented architecture for service delivery management

Abstract: IT (information technology) service providers often assume that efficient and effective service delivery can be achieved by migrating to a standard set of tools. This assumption is true only if the service provider has monolithic control over the scope and architecture of the customer environment. The trend, however, is toward selective outsourcing, customer control over the architecture of IT solutions, and retention of legacy tools. Target environments are extremely heterogeneous, and the ability of the service provider to control them is diminishing. Consequently, there is a need for a new approach to IT service workflow automation and a new generation of service-delivery management systems that support heterogeneity and collaboration. This paper introduces a new approach to automating complex and variable workflows, applies this approach to IT service delivery management (SDM), presents an SDM architecture based on this approach, and discusses an SDM implementation driven by this architecture. Our implementation architecture leverages service-oriented architecture (SOA) principles by defining loosely coupled service components and a service fulfillment pattern that dynamically integrates them. We discuss the modeling of performance metrics for service delivery and describe how the monitoring and management of key performance indicators (KPIs) are supported as an integral part of our SDM platform.

Model-driven Composition of Context-aware Web Services Using ContextUML and Aspects

Abstract: Service oriented architectures (SOAs) are constantly gaining ground for the provision of business to business as well as user-centric services, mainly in the form of Web services technology. SOAs enable service providers to design and deploy new,composite service offerings out of existing component services. In order to match end-user expectations with respect to personalization and ease of use, these services should be designed in a manner that allows them to exhibit a certain level of context-awareness which is a basic element towards a richer end-user experience. However, in the majority of such services, context-handling is still tightly coupled with the core functionality of the service, resulting in a design which is difficult to implement and maintain. The paper proposes the decoupling of core service logic from context-related functionality by adopting a model-driven approach based on a modified version of the ContextUML metamodel. Core service logic and context handling are treated as separate concerns at the modeling level as well as in the resulting source code where aspect oriented programming (AOP) encapsulates context-dependent behavior in discrete code modules. The design of a restaurant finder service is used to portray the modified ContextUML metamodel and the service modeling process which is covered in full. Respective code snippets belonging to the executable version of the service (part of work in progress) are also provided, illustrating the transition from model to code and the resulting separation of concerns.

Mobile communication service bridging

Abstract: A system is disclosed that provides functionality for mobile communications service bridging with distributed service gateway call managers that allow application clients running on users' communication devices to be served by any of the available service gateways, preferably in an active-active load balance configuration. Each service gateway instance may bridge the application client to a range of network services such as voice origination and termination services, IM services, messaging services, online community services, IP voice services, and premium services such as multiparty click-to-conference, directory services, and voice mail.

System and method for integrating a business process management system with an enterprise service bus

Abstract: A system and method are described for integrating a business process management (BPM) system with an enterprise service bus. The BPM system is used to model business processes which contain a set of activities linked by transitions. The BPM system is used to define, publish, deploy and execute the processes in a distributed computing environment. The service bus is used to manage web services and perform routing and transformation of messages between the web services. A transport is used to describe each process defined by the BPM system as a web service on the service bus and provide the ability to connect the BPM component to the enterprise service bus. This allows each of the processes to be exposed as a web service by injecting data retrieved from the process definition into the enterprise service bus. Furthermore, the processes defined in BPM can consume web services from the service bus.

Method and apparatus for middleware assisted system integration in a federated environment

Abstract: The present invention provides a computer implemented method, data processing system, and computer usable program code for instantiating a service on a network (100). A service infrastructure manager (524, 702) determines whether a service (718a, 718b, 718c) is available at a requested quality of service in response to receiving (802) a request for the service that specifies the quality of service. The service infrastructure manager (524, 702) performs (804) an analysis of components associated with the service (718a, 718b, 718c) to identify resources (716a, 716b, 716c) needed to create the service in response to the service (718a, 718b, 718c) being unavailable at the requested quality of service. Based on the analysis, the service infrastructure manager (524, 702) allocates resources (716a, 716b, 716c) to support the service (718a, 718b, 718c) and instantiates the service (718a, 718b, 718c) at the requested quality of service after the resources (716a, 716b, 716c) have been allocated.

Semantic Service Bus: Architecture and Implementation of a Next Generation Middleware

Abstract: In this paper we present a middleware for the service oriented architecture, called the Semantic Service Bus. It is an advanced middleware possessing enhanced features, as compared to the conventional service buses. It is distinguished by the fact that it uses semantic description of service capabilities, and requirements towards services to enable more elaborate service discovery, selection, routing, composition and data mediation. The contributions of the paper are the conceptual architecture of the Semantic Service Bus and a prototypical implementation supporting different semantic Web service technologies (OWL-S and WSMO) and conventional Web services. Since mission critical application scenarios (for SOA) involve complex orchestrations of services, we have chosen to utilize semantically annotated service orchestrations as the applications to employ this middleware.

Speeding up adaptation of web service compositions using expiration times

Abstract: Web processes must often operate in volatile environments where the quality of service parameters of the participating service providers change during the life time of the process. In order to remain optimal, the Web process must adapt to these changes. Adaptation requires knowledge about the parameter changes of each of the service providers and using this knowledge to determine whether the Web process should make a different more optimal decision. Previously, we defined a mechanism called the value of changed information which measures the impact of expected changes in the service parameters on the Web process, thereby offering a way to query and incorporate those changes that are useful and cost-efficient. However, computing the value of changed information incurs a substantial computational overhead. In this paper, we use service expiration times obtained from pre-defined service level agreements to reduce the computational overhead of adaptation. We formalize the intuition that services whose parameters have not expired need not be considered for querying for revised information. Using two realistic scenarios, we illustrate our approach and demonstrate the associated computational savings.