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Service reusability and other principles
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 Service reusability and its relationship with
other service-orientation principles.
When a service encapsulates logic that is useful to more than one service requestor, it can be considered reusable. The concept of reuse is supported by a number of complementary service principles, as follows.
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Service autonomy establishes an execution environment that facilitates reuse because the service has independence and self-governance. The less dependencies a service has, the broader its reuse applicability.
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Service statelessness supports reuse because it maximizes the availability of a service, and typically promotes a generic service design that defers activity-specific processing outside of service logic boundaries.
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Service abstraction fosters reuse because it establishes the black box concept, where processing details are completely hidden from requestors. This allows a service to simply express a generic public interface.
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Service discoverability promotes reuse, as it allows requestors (and those that build requestors) to search for and discover reusable services.
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Service loose coupling establishes an inherent independence that frees a service from immediate ties to others. This makes it a great deal easier to realize reuse.
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Additionally, the principle of service reuse itself enables the following related principle:
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Service composability is primarily possible because of reuse. The ability for one service to compose an activity around the utilization of a collection of services is feasible when those services being composed are built for reuse. (It is technically possible to build a service so that its sole purpose is to be composed by another, but reuse is generally emphasized.)
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This page contains excerpts from:
Service-Oriented Architecture:
Concepts, Technology, and Design
by Thomas Erl
(ISBN: 0131858580, Prentice Hall/PearsonPTR, Hardcover, 792 pages).
For more information, visit www.soabooks.com.
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