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Friday, April 15, 2011

What are different types of design patterns?

The Composite View Design Pattern
- The context of composite view pattern is that it allows the development of the view more manageable through the creation of a template to handle common page elements for a view.
- The problem comes in modifying and managing the layout of multiple views.
- The solution is to use this pattern when a view is composed of multiple atomic sub-views. Each component of the template may be included into the whole and the layout of the page may be managed independently of the content.
- A benefit of using this pattern is that interface designer can prototype the layout of the page, plugging in static content on each component.
- The drawback is that there is a runtime overhead associated with it.

The Front Controller Design Pattern
- It provides a centralized controller for managing requests.
- The problem is that the system needs a centralized access point for presentation-tier request handling to support the integration of system data retrieval, view management, and navigation.
- The solution to the above problem is that a controller is used as an initial point of contact for handling a request. It centralizes decision-making controls.

Data Access Object Design Pattern
- It separates resource's client interface from its data access mechanisms.It allows data access mechanism to change independently of the code that uses the data.
- The problem is that data will be coming from different persistent storage mechanism and access mechanism varies based on the type of storage.
- The solution to the above problem is to use the Data Access Object to abstract and encapsulate all access to the data source. It implements the access mechanism required to work with the data source.

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