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Design Principle

by Dinh Khoa Nguyen last modified Apr 26, 2012 11:13
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Design Principles
Domain: Cross-cutting issues
Engineering and Design
Adaptation and Monitoring
Quality Definition, Negotiation and Assurance
(domain independent)

Business Process Management

Service Composition and Coordination
In order to design useful and reliable business processes that are developed on the basis of existing or newly coded services we need to apply sound design principles that guarantee that services are self-contained and come equipped with clearly defined boundaries and service end-points to allow for service composability. Two key principles serve as the foundation for service design: service coupling and cohesion. The purpose of these two principles is to create services that encompass the right amount of functionality to be useful and to encourage code reuse. Service coupling and cohesion are inextricably associated with service granularity. [Papazoglou 2007]

One way of measuring service design quality is coupling, or the degree of interdependence between two service compositions. It is important that grouping of activities in service compositions is as independent as possible from other such groupings in other service compositions. The objective is to minimize coupling, that is, to make (self-contained) service compositions as independent as possible by not having any knowledge of or relying on any other service compositions. Low coupling between service compositions indicates a well-partitioned system that avoids the problems of service redundancy and duplication.

Cohesion is the degree of the strength of functional relatedness of operations within a service. Service developers should create strong, highly cohesive service compositions; service compositions whose services and service operations are strongly and genuinely related to one another. A service composition with highly related services and related responsibilities, which also has a rather narrow scope, has high design cohesion. [Papazoglou 2007]

Service Infrastructure

(domain independent)

Design principles are a set of principles that are applied during the design of a software system. For example, a design principle that may be applied during the design of adaptable service-based applications is: one must consider which adaptation strategies satisfy the application's adaptation requirements. [CD-JRA-1.1.4]
Design principles describe fundamental ideas about the practice of good visual design that are assumed to be the basis of all intentional visual design strategies [Wikipedia].





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