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Component-Based Software Development (CBSD) is an approach that has many benefits, such as improving application developer productivity, reducing costs and complexity by reusing of existing codes. Programming within this approach is like assembly (i.e. composing software out of prefabricated components) rather than development, which reduces skill requirements, and allows expertise focuses on domain problems. The foundation of any CBSD methodology is its underlying component model, which defines what components are, how they can be constructed, and specifies the standards and conventions that are needed to enable composition of independently developed component. The current component models do not support composition in both design and deployment phase. They also focus on the specification and packaging of components but provide almost no support for the easy composition of components. Component in these models uses either direct or indirect message passing as connection schemes, which leads to tightly coupling (i.e. components mix computation with control). It is conclude that this research has proposed an effective way for component composition which provides loosely coupling between composed components. For system maintenance and evolution, this decoupling should make it simpler to manage changes in the components, and also changes in the connector separately. This research has resulted in the proposed of mediator connector which is similar to a communication hub. It initiates method calls and manages the returns, and also provides total loosely coupling between components and also itself. Mediator connector is a framework and can be reused without any modification. The components composition using mediator connector belongs to the deployment phase. Our approach is based on interactions between components as a subset of behavior in a system. In order to minimize coupling between components and mediator connector, we have designed and developed an XML-based language, called Component Interaction Markup Language (CIML), where components as well as their interactions are described in a CIML document which are used by mediator connector. For evaluation of mediator connector in order to measure the loosely coupling it provides, four case studies have been tested. To measure coupling we applied Coupling Between Object (CBO) software metric. The result shows that mediator connector provides totally loosely coupling between software components composing in the deployment phase. |
