Exhibit 9.4 illustrates an
SOA layered architecture formation. Note the bidirectional interaction between the top and the
bottom layers.
Endpoints Access Layer
Core Business Products -Services Layer
ESB Layer
Repository Policy Layer
UDDI Registry Layer
EXHIBIT 9.4 SOA LAYERED ARCHITECTURE FORMATION EXAMPLE
Business Model Perspectives 181
Distributed Architectures. The distributed architecture paradigm advocates the partitioning of
functionalities into disparate software components and dispersing them over a network. While
these separated autonomous software executables operate simultaneously, they collectively provide
viable remedies to organizational problems. So why should they be discerned? There are
many reasons for decoupling software logic into smaller parts. The chief reason is to facilitate a
higher level of component and service reusability. Tightly coupled systems limit the mobility of
their components and services and reduce reusability factors.
Furthermore, interoperability is another vital aspect of core business products. Distributed
architectures thus enable collaboration of systems, services, and consumers that operate in mixed
technological environments, platforms, or operating systems. Organizations that encourage distribution
of assets, however, must be aware of coordination disadvantages when it comes to
executing transactions. Andrew S. Tanenbaum, in his book Modern Operating Systems, argues
that a fine balance must be maintained between centralized and distributed systems.
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