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 ...

12.07.2015 Views

Chapter 3. Architectural Patterns 38Figure 3.3: Lazy Acquisition design patternRole of particular elements:1. Resource proxy – simulates requested resource by providing an interfacethat is identical with interface of the requested resource. provider.2. Resource provider –provides resource to resource proxy.3. Resource –contains resources that are obtained through the resource proxy.It is possible to make a whole system implemented using this pattern. Theelements of design pattern have to be converted into subsystems. Additionally,an access interface is needed. Resource provider becomes a subsystem responsiblefor providing resources. It is invoked by access interface. This subsysteminvokes Resource Proxy subsystem. Resource Proxy is responsible for convertingobtained resources into proxies. The system also lazy initiates the proxies if it isneeded. Resource subsystem is responsible for providing required resources. Thesubsystem maintains also connections to database and executes other databaserelated operations. The overview of architecture of this system is determined bya design pattern what in this case makes it an architectural pattern because thepattern does not affect only particular subsystem as definition of Design Patternsays. It defines the subsystems and interactions between them (see figure3.4). Application of the design pattern matches to previously stated definition ofArchitectural Pattern.Applying design patters as architectural pattern is not the only problem inpattern distinguishing. How close are those two types of patterns can be seenin literature [34], where Model View Controller (MVC) pattern is described as

Chapter 3. Architectural Patterns 39Figure 3.4: Lazy Acquisition as architectural patterna composed design pattern, while Bushman for instance presents MVC as anarchitectural pattern [22]3.1.3 Sources of Architectural PatternsFilter 1: Selection of Literature SourcesThe idea of Architectural Patterns in Software Engineering is relatively old andpopular thus there are a number of publications about this particular type ofpattern. Unfortunately, there is no standardized set of architectural patterns.Different authors present their own definitions of architectural patterns and proposetheir own categorisation of those patterns. The process of selection of anarchitectural pattern for migration to SOA requires a number of patterns to revisein order to select the most appropriate pattern. Due to a significant numberof publications, it is impossible to identify all Architectural Patterns in SoftwareEngineering. The initial list of patterns has to be created based on a sized downlist of publication. The initial list of patterns bases on three sources:

Chapter 3. <strong>Architectural</strong> <strong>Pattern</strong>s 39Figure 3.4: Lazy Acquisition as architectural patterna composed design pattern, while Bushman for instance presents MVC as anarchitectural pattern [22]3.1.3 Sources <strong>of</strong> <strong>Architectural</strong> <strong>Pattern</strong>sFilter 1: Selection <strong>of</strong> Literature SourcesThe idea <strong>of</strong> <strong>Architectural</strong> <strong>Pattern</strong>s in S<strong>of</strong>tware Engineering is relatively old andpopular thus there are a number <strong>of</strong> publications about this particular type <strong>of</strong>pattern. Unfortunately, there is no standardized set <strong>of</strong> architectural patterns.Different authors present their own definitions <strong>of</strong> architectural patterns and proposetheir own categorisation <strong>of</strong> those patterns. The process <strong>of</strong> selection <strong>of</strong> anarchitectural pattern for migration <strong>to</strong> SOA requires a number <strong>of</strong> patterns <strong>to</strong> revisein order <strong>to</strong> select the most appropriate pattern. Due <strong>to</strong> a significant number<strong>of</strong> publications, it is impossible <strong>to</strong> identify all <strong>Architectural</strong> <strong>Pattern</strong>s in S<strong>of</strong>twareEngineering. The initial list <strong>of</strong> patterns has <strong>to</strong> be created based on a sized downlist <strong>of</strong> publication. The initial list <strong>of</strong> patterns bases on three sources:

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