Scope & Span: Web Services, Loose Coupling & Functional Commoditization The trend towards component-based software and web services is an evolution of software to realize economies of Scope and Span.
App Servers have embraced J2EE (and MS embraced its .NET) and development frameworks have evolved to support component-based software development. XML standards provide further functional defintions of component commodities. Components can be functionally repurposed with minimal transaction costs, realizing economies of Scope and significant risk reduction
Web Services goes beyond scope by leveraging XML standard interfaces and common Internet protocols to realize span in distributed architectures. With standard definitions and interfaces, essentially becoming commoditized, components can be efficiently sequenced with low transaction costs to realize Economies fo Span.
The value of this model is the functional commoditization. Functional, in that the technology can be repurposed at a low transaction cost. Commoditization, in that it has a standard definition and interface. Add a contract and business processes to the underlying functionality and commodity and you have a service. Functional commoditization is another way to describe Loose Coupling.
We are a long way from the vision of portfolio management of distributed software components. Unlike managing a portfolio of financial securities, technology assets posess systemic characteristics. A portfolio of technology assets realizes diversification benefits from both being diverse and the properties of Scope technologies. The combinatorial value of Span technologies realizes network effects within the portfolio.
Today's evolution in software architecture towards Service Oriented Architectures marks a shift from more static systems that emphasized Speed and Scale towards dynamic systems that realize Scope and Span. The shift is made possible by the adoption of standards, but is driven by change requirements of competitive turbulence.
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