Preparing for Service-Oriented Computing: A Composite Design Pattern for Stubless Web Service Invocation

Abstract

Abstract. The ability to dynamically bind to Web services at runtime is becoming increasingly important as the era of Service-Oriented Computing (SOC) emerges. With SOC selection and invocation of Web service partners will occur in software at run-time, rather than by software developers at design and compile time. Unfortunately, the marketplace has yet to yield a predominate applications programming interface for the invocation of Web services. This results in software that is deeply ingrained with vendor-specific calls. This is problematic because Web service technology is changing at a rapid pace. In order to leverage the latest developments, code often needs to be heavily refactored to account for changing invocation interfaces. This paper explores the mitigation of this problem through the application of software design patterns. Specifically, it details how a Web service architectural pattern, based upon the composition of software design patterns, provides for implementations that insulate the application code from the peculiarities of any specific vendor's interface.

Dynamic Service Composition: A Discovery-Based Approach

“…(5) SCE awards the tasks to the chosen web services. (6) The matched web services hosted on SPE begin to perform the task and return the service results to SCE. Figure 10 contains two instances of the "loop" operator, each adopted in a different way.…”

“…Buhler et al [6] developed a composite design pattern for "stubless" web service invocation, based on the Bridge and Factory Method patterns. This composite pattern provides an agile software design for decoupling the invocation services that are found and bound at run-time.…”

A Dynamic Composition and Stubless Invocation Approach for Information-Providing Services

“…Several existing Web Services invocation frameworks (e.g., Apache WSIF [8], Apache Axis 2 [9], Codehaus XFire [10], Apache CXF [11], and Java API for XML-based Web Services [12]) provide some capabilities for late binding to Web Services (e.g., via dynamic proxying). A weakness of these solutions is that the client code is highly dependent upon specific toolkit APIs [13].…”

A framework for multimedia collaborative spaces

“…Buhler, Starr, Schroder and Vidal (2004) [15] argued that such functionality requires agile software structures that support loosely coupled interactions of services that are found and bonded to at run-time. They proposed a "stubless" Web Service invocation and predicted that stubless web invocation will gain more ground as more and more SOC systems are deployed.…”

“…There are about 180 million persons, or about 3% of the world population, who are broadband subscribers around the globe as of mid-2005 with a steady growth momentum being sustained from year to year [36], According to Internet World Stats one billion or 15.7% o f the world population have Internet access [37], If we merge the two statistics together, we find that about 18% of the people with Internet access are broadband users.…”