Christopher P. Vignola

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.

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.

MVS/ESA coupled-systems considerations

One of the most important future MVS environments will be to provide on-line transaction processing and decision support through the use of large data “warehouses” in heterogeneous networks. To provide the large capacity and high availability required for this environment, it will be necessary to use multiple, cooperating MVS systems to provide those services. The design of such coupled MVS systems must accommodate a number of factors related to both the general environment and the users needs, including availability, growth, granularity and scale, systems management, migration and coexistence, and single-system images. In this paper, we describe the system services available with MVS/ESA™ SP Version 4 that can support the coupled-systems environment, and discuss how those services can be exploited.