Information Technology Reference
In-Depth Information
8.1
The service-oriented paradigm continues to gain traction in grid comput-
ing. Open-grid services architecture (OGSA) has dei ned a service-oriented
grid-computing environment based on existing Web service standards
and technologies. As more and more grid resources are made available
as grid services in practice, it has become commonly understood that a
solution that can combine and coordinate existing services into useful
application logic is needed. Considered to be a key element toward a fully
integrated service-oriented architecture, business process execution lan-
guage (BPEL) is the
de facto
standard for Web service orchestration in
industry, providing the models and language specii cation for dei ning
executable application workl ows based on service invocations. It is in our
interest to explore the applicability of using BPEL in grid applications.
Use of workl ows allows the abstraction of process logic in a more
human-friendly manner. To a certain extent, consideration of implementa-
tion details will no longer be required. Instead, people can focus on the
development of a process model and the specii c workl ow interpretation.
In grid computing, workl ows are useful for the manner in which they
facilitate the modeling and the automation of large-scale concurrent pro-
cesses. A variety of workl ow systems, or similar, exists, targeting different
technologies, levels of abstraction, application domains, formalisms, and
so on. A service-oriented paradigm is deemed to change the mindset of
distributed computing in general and will provide us with new possibili-
ties for problem solving with architectural approaches.
OMII-BPEL contributes to the initial attempts of using BPEL for grid
workl ows modeling and execution. The project studied the language
expressiveness for grid-specii c requirements, looked at existing BPEL
resources and how they may be leveraged in a grid environment. An inte-
grated BPEL development toolkit has been developed under the OMII
(Open Middleware Infrastructure Institute) stack for the UK e-Science
community. Through user feedback and conducted research, the project is
devoted to improving user experiences on working with BPEL in scientii c
grid computing.
In the rest of this chapter, we will i rst get to learn some important features
of BPEL and focus on how they are related to grid workl ow modeling. This
is then followed by an introduction to the OMII-BPEL software bundle,
through which we highlight the specii c requirements and characteristics
of grid service orchestration and how users are supported by the tools and
Introduction
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