Migration of a Chosen Architectural Pattern to Service Oriented ...
Migration of a Chosen Architectural Pattern to Service Oriented ...
Migration of a Chosen Architectural Pattern to Service Oriented ...
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Chapter 4. <strong>Service</strong> <strong>Oriented</strong> Architecture 754.1 Definition <strong>of</strong> <strong>Service</strong> <strong>Oriented</strong> ArchitectureThere are many definitions <strong>of</strong> SOA in literature. The definitions differ in terms<strong>of</strong> scope and details. In general, the definitions underline business or technicalaspects <strong>of</strong> SA. An example <strong>of</strong> business-focused definition is provided by ThomasErl [31]:“SOA establishes an architectural model that aims <strong>to</strong> enhance the efficiency,agility, and productivity <strong>of</strong> an enterprise by positioning services as the primarymeans through which solution logic is represented in support <strong>of</strong> the realisation <strong>of</strong>strategic goals associated with service–oriented computing.”Other business focussed definition says that SOA is [13]: “A set <strong>of</strong> business,process, organizational, governance, and technical methods <strong>to</strong> reduce or eliminatefrustrations with IT and <strong>to</strong> quantifiably measure the business value <strong>of</strong> IT whilecreating an agile business environment for competitive advantage.”While business view on SOA is important and cannot be neglected, the thesisfocuses on architectural aspect <strong>of</strong> <strong>Service</strong> <strong>Oriented</strong> Architecture. “Architecture”or more precisely on “S<strong>of</strong>tware Architecture”. S<strong>of</strong>tware Architecture [39]:”is nota project plan that describes activities and staffing for designing the architectureor developing the product. Instead it is a structural plan that describes the elements<strong>of</strong> the system, how they fit <strong>to</strong>gether and how they work <strong>to</strong>gether <strong>to</strong> fulfil thesystem’s requirements. It is used as a blueprint during the development process,and it is also used <strong>to</strong> negotiate system requirements(...)”The definition <strong>of</strong> SOA from architectural point <strong>of</strong> view must align <strong>to</strong> the definition<strong>of</strong> S<strong>of</strong>tware architecture presented above. A strict definition <strong>of</strong> <strong>Service</strong><strong>Oriented</strong> Architecture, which includes aspects <strong>of</strong> the S<strong>of</strong>t- ware Architecture ispresented by Krafzig [46]:A <strong>Service</strong>–<strong>Oriented</strong> Architecture (SOA) is a s<strong>of</strong>tware architecture that is basedon the key concepts <strong>of</strong> an application frontend, service, service reposi<strong>to</strong>ry, andservice bus. A service consists <strong>of</strong> a contract, one or more interfaces, and an implementation.The definition <strong>of</strong> SOA presented by Krafzig is the definition used in this thesis.Each time the term SOA is recalled, it refers <strong>to</strong> this definition unless it is statedexplicitly that other definition is applied. The definition as presented by Krafzigincludes structural aspects <strong>of</strong> an architecture using several other terms. Theexplanation those terms is presented in the section below.
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