Ru Fang

A Version-aware Approach for Web Service Directory

In real-world scenarios, the evolution of Web services to meet functional and non-functional changes ultimately leads to multiple versions of the same original service. Thus, design and implementation of version management techniques, such as version description, directory, etc, play a critical role in realizing the full promise of SOA. To address the version management issues in Web services, we propose a version-aware service model based on some architectural extensions to WSDL and UDDI. WSDL would be enhanced to describe the attributes of the service versions. UDDI would be augmented to use versions in a service directory with an event-based notification/subscription mechanism. We also design a proxy, residing in the service consumer side which can dynamically update the client application instance at runtime. We have implemented a prototype to demonstrate these models and used a weather forecast web service as an example to illustrate the usefulness of the proposed architecture.

Using an Interface Proxy to Host Versioned Web Services

Web services have become important building blocks of distributed applications and have matured to the point where service lifecycle issues such as version management are now paramount. However, there is a lack of versioning support in relevant standards and tools. We present an approach which leverages the existing WSDL service definition model to build a versioned service hosting solution. We distinguish between a Web service interface (published) version and its implementation version (private). We introduce the concept of a service interface proxy. This proxy, which can be generated automatically, implicitly defines the service interface version, and is published as the logical service endpoint. Client requests are routed dynamically by the proxy to appropriate implementation versions. We have implemented a prototype of our approach to demonstrate its applicability.

Dynamic Support for BPEL Process Instance Adaptation

Rapidly changing market conditions and IT systems are forcing companies to adapt their business processes more dynamically than in the past. Most current commercial BPMS products lack the full capability to support changing processes. To address this challenge, we discuss three aspects of dynamic adaptation in a BPM system: model-level, instance-level, and runtime environment changes. We focus on analyzing the patterns of the instance-level navigation changes, including the preconditions, actions and consequences of each change. Based on this analysis, we propose a system design for the runtime environment to support dynamic instance-level changes. We have implemented a prototype of such a system with the motivating scenarios to demonstrate the usefulness of our proposal.

On Synchronizing with Web Service Evolution

To catch up with todays fast changing business markets, web services has never slowed down its paces for evolution. As a consequence, service consumers have to employ in-time upgrades to guarantee continuous business integrity and avoid unnecessary runtime errors in their IT systems. However, a new web service release can involve hundreds of changes, and thus it is non-trivial for the service consumer to rapidly track and adopt relevant changes. This paper proposes a framework for facilitating the service consumer to keep synchronized with the web service evolution. On the service side, a Service Invocation Monitor is installed to monitor the interaction history of the client, a Service Delta Analyzer exports the service delta into well-formatted document, and a Release Note Customizeris configured to customize the full release note produced using the monitored interaction history and exported service delta. On the client side, the Consumer Code Customizer is used by the consumer developer to highlight the code fragments to be changed and provide facilitation linkages between the code fragments and the customized release note. An example is shown to demonstrate the usefulness of our proposal.

A Version-aware Approach for Web Service Client Application

An increasing number of enterprises demonstrate that successful adoption of service oriented architecture (SOA) using Web services technologies enables them to build enterprise applications quickly and effectively. To align with changing business requirement, services need to adapt quickly, and eventually multiple versions of the same original service would coexist. To manage all these versions and ensure continuous availability to the service consumers, innovative techniques of version management for Web services become critical to realizing the full promise of SOA. To address the version management issues in Web services, we propose to include version-awareness to various aspects of Web services as an extension to the current SOA In particular, to minimize the impact of service changes on the service consumer side, we design a version-aware Web service client model (via an enhancement to the current JAX-RPC client model) which provides both consumer-aware and consumer-transparent invocation styles at build-time and dynamic service proxy generation at runtime. Leveraging the present implementation of the JAX-RPC service model, the versioned client APIs based on the new client model is designed to make the development process easy and intuitive. A prototype of this client model, implemented in Eclipse with an exemplary weather-forecast application, is introduced to demonstrate the usefulness of the proposed approach.

A comprehensive semantic-based resource allocation framework for workflow management systems

Resource allocation that targets to assign the appropriate resource to the dynamically generated work item has always been a critical issue in the workflow management system research. However, todays workflow systems almost still depend on the static literal-based matchmaking mechanism to support the resource allocation, which would suffer greatly from the diversity and mutability of resources in current open and dynamic network environment. In this paper, we propose a comprehensive semantic-based resource allocation framework to enhance the matchmaking process. The essential contributions of this framework are: firstly, an OWL ontology is provided to describe available resources based on their semantic information. Secondly, based on the ontology, effective semantic reasoning techniques are used to select the eligible resource candidates. Thirdly, a bidding approach is adopted to further optimize the resource selection according to runtime conditions such as duration, cost and etc., which would typically overcome the inaccurate assignment based on pure static information in previous study.

Process Guided Service Composition in Building SoA Solutions:A Data Driven Approach

Solution design has been more of an art than an engineering discipline. Lots of researchers and practitioners have proposed and exercised different kinds of approaches with varied success. Most of these methods seem to have focused on building new solutions from scratch. However, enterprise solutions today are mostly built on top of an existing IT infrastructure. The notion of SoA is trying to pave a way to integrate heterogeneous components together to meet new business needs. When a new requirement is given to a system developer in the form of business processes, it would be ideal if she/he can make the best of existing services for many reasons. In this paper we propose a data driven approach to provide service composition guidance to implement the given requirement. Based on the relations among business domain data and service domain data, we can generate additional data mediations according to three composition rules. With these data relations and composition rules, we give a formal approach to devise choreography of services from current service portfolio, plus additional data mediation artifacts to realize a given requirement. Our work can be seen as an effort to bridge the gap between business and service domain