Unity was designed to achieve the following goals:

• Promote the principles of modular design through aggressive decoupling.
• Raise awareness of the need to maximize testability when designing applications.
• Provide a fast and lightweight dependency injection container mechanism for creating new object instances and managing existing object instances.
• Expose a compact and intuitive API for developers to work with the container.
• Support a wide range of code languages, with method overrides that accept generic parameters where the language supports these.
• Implement attribute-driven injection for constructors, property setters, and methods of target objects.
• Provide extensibility through custom and third-party container extensions.
• Provide the performance required in enterprise-level line of business (LOB) applications.

Operation

The public methods of the UnityContainer that developers use fall into two main categories:

• Methods that register mappings or types. The methods RegisterType and the RegisterInstance create the appropriate entries within the current container context.
• Methods that retrieve objects. These include overrides of the Resolve, ResolveAll, and BuildUp methods. These methods retrieve the required instances of the objects.