One of the most relevant issue in software architecture is how to separate the implementation of cross-cutting concerns from the implementation of the core-concerns.
A cross-cutting concern is a concern that affects multiple components in a system, such as logging, security, and exception handling.
Microsoft's Unity Application Block (Unity for short), that is part of the Microsoft Enterprise Library 5.0, enable you to effectively capture calls to objects and add additional functionality to the target object. More...

The factory design pattern is a creational pattern that favor the abstraction of the objects creation's process.
The creation of an object can be a complex process where many properties must be setted and other nested objects must be created.
To reduce the code duplication and the coupling between classes, is better to put the creation code in a unique place (the factory), where you can access to get the instance of the objects.
A "factory" therefore, is an object for creating other objects. More...

Another way to implement the Inversion of Control (IoC) principle, in addition to the Dependency Injection, is the plug-in design pattern.

The pattern consists in to load an assembly that implements a common interface at runtime. In this way, a class that depends from an object in an other assemby is completely decoupled from it, or rather, it has no reference to dependent assembly. More...

In the observer design pattern an object (the observable) mantain a list of its dependents (the observers) and notifies them when its state changes by calling a method on each registered subscribers. More...

The Separated Interface pattern addresses the problem of separating the interface that describes the functionalities from its implementation. The pattern prescribes that you use different packages (assemblies in the .NET Framework) for the interface and any of its implementations. The packages that need to consume the functionalities know only the definition of the interface and are completely unaware of the implementation. More...

Dependency Injection (DI) is a design pattern that strive to reduce the dependency between components. Dependency Injection is often referred as Inversion of Control (IoC). In fact dependency injection is an application of the Inversion of Control principle.

A class that depends from an other object, receive the reference of the dependent object from the outside world instead of create the instance itself. More...

The singleton design pattern force to have only one instance of a class.
The implementation require a mechanism to access the same instance of the class without recreate it every time. It can be achieved creating a class with a method that creates a new instance of the class if one does not exist. If an instance already exists, it simply returns a reference to that object. To make sure that the object cannot be instantiated any other way, the constructor is made protected. More...