Migration of a Chosen Architectural Pattern to Service Oriented ...

Chapter 4. Service Oriented Architecture 824.3.2 ActivitiesActivities are building blocks of methodologies [13].Each activity derives from amethod principle, constrains or good practices applied in this particular approach.This section discusses a set of common activities required to create Service OrientedArchitecture [13]. The activities are presented in sequence so the firstdescription matches the first activity that should be executed and so on.Service Identification – The goal is to identify services by using supportingtechniques like Input Analysis, Top–down Analysis, Bottom -up Synthesis orTaxonomy Building. However all those techniques can be used separately andguarantee useful output, the best result is achieved by mixing the approaches.This step creates a baseline for further analysis and modelling. The supportingtechniques can be defined as follows:1. Input Analysis [13] requires documentation or business models of the systems,therefore it is applicable to legacy system analysis. According to [13],Input Analysis may be driven answers to following questions:(a) Are the business drivers and goals for the SOA project articulated andquantifiable in terms of key business performance indicators?(b) Have the business processes to be realized been named and described ata level of detail that is sufficient for architectural decision–making atthe IT level?(c) Have the existing and future non–functional requirements been documentedwith any unresolved pain points?2. Top–identifies high-level business concerns in order to capture and modelrequirements [13]. There is no “best solution” for this type of analysis,however it can be implemented using even very basic elicitation techniqueslike interview. The main benefit of this technique is that it does not gointo details on object level. Object level analysis may lead to impossible tomanage “net” of classes and their relationship.3. Taxonomy Building uses semantic of word used within the company takinginto consideration both technical and business aspects[13].As the result, adictionary is elaborated. The dictionary describes all the processes and dependenciesbetween them and this is a good starting point for service identification.Creation of services depends on terms in the elaborated dictionaryand relations between those terms. The most frequent used words identifyentities, rules, processes or others elements of the system that shouldbe encapsulated in a service. Successful realization of taxonomy buildingestablishes also unified vocabulary that improves communication betweenteams.