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Eclipse Gemini Blueprint is the reference implementation for the OSGi Alliance Blueprint Service (chapter 121 of the OSGi 4.2 Compendium Specification). Gemini Blueprint project makes it easy to build Java applications that run in an OSGi framework. By using Gemini Blueprint, applications benefit from using a better separation of modules, the ability to dynamically add, remove, and update modules in a running system, the ability to deploy multiple versions of a module simultaneously (and have clients automatically bind to the appropriate one), and a dynamic service model. Gemini users may also be interested in Eclipse Virgo, an open source, completely modular, OSGi-based Java application server. Its documentation is considered a supplement to Gemini Blueprint as it explains in detail, how OSGi can be used in various development and production scenarios.

By applying the Model-View-Controller (MVC) architecture to a JavaTM 2 Platform, Enterprise Edition (J2EETM) application, you separate core business model functionality from the presentation and control logic that uses this functionality. Such separation allows multiple views to share the same enterprise data model, which makes supporting multiple clients easier to implement, test, and maintain.

Java BluePrints Model-View-Controller

Many interactive Web applications are composed of brittle collections of interdependent Web pages. Such applications can be hard to maintain and extend. The Front Controller pattern defines a single component that is responsible for processing application requests. A front controller centralizes functions such as view selection, security, and templating, and applies them consistently across all pages or views. Consequently, when the behavior of these functions need to change, only a small part of the application needs to be changed: the controller and its helper classes.

Many interactive Web applications are composed of brittle collections of interdependent Web pages. Such applications can be hard to maintain and extend. The Front Controller pattern defines a single component that is responsible for processing application requests. A front controller centralizes functions such as view selection, security, and templating, and applies them consistently across all pages or views. Consequently, when the behavior of these functions need to change, only a small part of the application needs to be changed: the controller and its helper classes.

An interface is a blueprint of a class. It has static constants and abstract methods. The interface is a mechanism to achieve fully abstraction in java. There can be only abstract methods in the interface. It is used to achieve fully abstraction and multiple inheritance in Java. Interface also represents IS-A relationship.