Liangzhao Zeng

QoS-aware middleware for Web services composition

The paradigmatic shift from a Web of manual interactions to a Web of programmatic interactions driven by Web services is creating unprecedented opportunities for the formation of online business-to-business (B2B) collaborations. In particular, the creation of value-added services by composition of existing ones is gaining a significant momentum. Since many available Web services provide overlapping or identical functionality, albeit with different quality of service (QoS), a choice needs to be made to determine which services are to participate in a given composite service. This paper presents a middleware platform which addresses the issue of selecting Web services for the purpose of their composition in a way that maximizes user satisfaction expressed as utility functions over QoS attributes, while satisfying the constraints set by the user and by the structure of the composite service. Two selection approaches are described and compared: one based on local (task-level) selection of services and the other based on global allocation of tasks to services using integer programming.

Quality driven web services composition

The process-driven composition of Web services is emerging as a promising approach to integrate business applications within and across organizational boundaries. In this approach, individual Web services are federated into composite Web services whose business logic is expressed as a process model. The tasks of this process model are essentially invocations to functionalities offered by the underlying component services. Usually, several component services are able to execute a given task, although with different levels of pricing and quality. In this paper, we advocate that the selection of component services should be carried out during the execution of a composite service, rather than at design-time. In addition, this selection should consider multiple criteria (e.g., price, duration, reliability), and it should take into account global constraints and preferences set by the user (e.g., budget constraints). Accordingly, the paper proposes a global planning approach to optimally select component services during the execution of a composite service. Service selection is formulated as an optimization problem which can be solved using efficient linear programming methods. Experimental results show that this global planning approach outperforms approaches in which the component services are selected individually for each task in a composite service.

Dynamic composition and optimization of Web services

Process-based composition of Web services has recently gained significant momentum for the implementation of inter-organizational business collaborations. In this approach, individual Web services are choreographed into composite Web services whose integration logics are expressed as composition schema. In this paper, we present a goal-directed composition framework to support on-demand business processes. Composition schemas are generated incrementally by a rule inference mechanism based on a set of domain-specific business rules enriched with contextual information. In situations where multiple composition schemas can achieve the same goal, we must first select the best composition schema, wherein the best schema is selected based on the combination of its estimated execution quality and schema quality. By coupling the dynamic schema creation and quality-driven selection strategy in one single framework, we ensure that the generated composite service comply with business rules when being adapted and optimized.

Monitoring the QoS for Web Services

Quality of Service (QoS) information for Web services is essential to QoS-aware service management and composition. Currently, most QoS-aware solutions assume that the QoS for component services is readily available, and that the QoS for composite services can be computed from the QoS for component services. The issue of how to obtain the QoS for component services has largely been overlooked. In this paper, we tackle this fundamental issue. We argue that most of QoS metrics can be observed/computed based on service operations. We present the design and implementation of a high-performance QoS monitoring system. The system is driven by a QoS observation model that defines IT- and business-level metrics and associated evaluation formulas. Integrated into the SOA infrastructure at large, the monitoring system can detect and route service operational events systemically. Further, a model-driven, hybrid compilation/interpretation approach is used in metric computation to process service operational events and maintain metrics efficiently. Experiments suggest that our system can support high event processing throughput and scales to the number of CPUs.

Flexible Composition of Enterprise Web Services

The process-based composition of Web services is emerging as a promising approach to automate business process within and across organizational boundaries. In this approach, individual Web services are federated into composite Web services whose business logic is expressed as a process model. Business process automation technology such as workflow management systems (WFMSs) can be used to choreograph the component services. However, one of the fundamental assumptions of most WFMSs is that workflow schemas are static and predefined. Such an assumption is impractical for business processes that have an explosive number of options, or dynamic business processes that must be generated and altered on the fly to meet rapid changing business conditions. In this paper, we describe a rule inference framework called DY flow , where end users declaratively define their business objectives or goals and the system dynamically composes Web services

Policy-driven exception-management for composite Web services

Process-based composition of Web services has recently gained significant momentum in the implementation of business processes. A critical and time-consuming part of business process development is the detection and handling of exceptions that may occur during process execution. In this paper, we introduce a novel, policy-driven approach to exception management, which substantially simplifies business process development. We advocate that exception management should be implemented in the system infrastructure. Using our exception management framework, developers define exception policies in a declarative manner. Before a business process is executed, the service composition middleware integrates the exception policies with normal business logic to generate an exception-aware process schema. We argue that our policy-driven approach significantly reduces the development time of business processes through its separation of the development of the business logic and the exception handling policies.

Event-Driven Quality of Service Prediction

Quality of Service Management (QoSM) is a new task in IT-enabled enterprises that supports monitoring, collecting and predicting QoS data. QoSM solutions must be able to efficiently process runtime events, compute and pre dict QoS metrics, and provide real-time visibility and prediction of key perform ance indicators (KPI). Currently, most QoSM systems focus on moni tor ing of QoS constraints, i.e., they report what has been happened. In a way, this provides the awareness of past developments and sets the basis for decisions. However, this kind of knowledge is afterwit. For example, it cannot provide early warnings to prevent the QoS degradation or the violation of commitments. In this paper, we move one step forward to provide QoS prediction. We argue that performance metrics and KPIs can be predicted based on historical data. We present the design and implementation of a novel event-driven QoS prediction system. Integrated into the SOA infrastructure at large, the prediction system can process operational service events in a real-time fashion, in order to predict or refine the prediction of metrics and KPIs.

Model driven development for business performance management

Business process integration and monitoring provides an invaluable means for an enterprise to adapt to changing conditions. However, developing such applications using traditional methods is challenging because of the intrinsic complexity of integrating large-scale business processes and existing applications. Model Driven DevelopmentTM (MDDTM) is an approach to developing applications-from domain-specific models to platform-sensitive models-that bridges the gap between business processes and information technology. We describe the MDD framework and methodology used to create the IBM Business Performance Management (BPM) solution. We describe how we apply model-driven techniques to BPM and present a scenario from a pilot project in which these techniques were applied. Technical details on models and transformation are presented. Our framework uses and extends the IBM business observation metamodel and introduces a data warehouse metamodel and other platform-specific and transformational models. We discuss our lessons learned and present the general guidelines for using MDD to develop enterprise-scale applications.

Secure Search of Private Documents in an Enterprise Content Management System

An enterprise content management system such as an electronic contract system manages a large number of secure documents for many organizations. The search of these private documents for different organizational users with role- based access control is a challenging task. In this paper, we present a novel content-based XML-annotated secure-index search mechanism that provides an effective search and retrieval of private documents with document-level security. The search mechanism includes a document analysis framework for text analysis and annotation, a search indexer to build and incorporate document access control information directly into a search index, an XML-based search engine, and a compound query generation technique to join user role and organization information into search query. Our experiments on a pilot electronic contract system demonstrate that, by incorporating document access information directly into the search index and combining user information in the search query, search and retrieval of private contract documents can be achieved very effectively and securely with high performance.

Automatic Mash Up of Composite Applications

The need for integration of both client and server applications that were not initially designed to interoperate is gaining popularity. One of the reasons for this popularity is the capability to quickly reconfigure a composite application for a task at hand, both by changing the set of components and the way they are interconnected. Service Oriented Architecture (SOA) has become a popular platform in the IT industry for building such composite applications recently with the integrated components being provided as web services. A key limitation of such a web service is that it requires extra programming efforts when integrating non web service components, which is not cost-effective. Moreover, with the emergence of new standards, such as OSGi, the components used in composite applications have grown to include more than just web services. Our work enables progressive composition of non web service based components such as portlets, web applications, native widgets, legacy systems, and Java Beans. Further, we proposed a novel application of semantic annotation together with the standard semantic web matching algorithm for finding sets of functionally equivalent components out of a large set of available non web service based components. Once such a set is identified the user can drag and drop the most suitable component into an Eclipse based composition canvas. After a set of components has been selected in such a way, they can be connected by data-flow arcs, thus forming an integrated, composite application without any low level programming and integration efforts. We implemented and conducted experimental study on the above progressive composition framework on IBMs Lotus Expeditor which is an extension of a Service Oriented Architecture (SOA) platform called the Eclipse Rich Client Platform (RCP) that complies with the OSGi standard.