Useful Design Patterns for Brownfield Projects

Brownfield projects are ubiquitous these days. Greenfield on the other-hand are hard to come by.
The ways to deal with both are different. In particular, design patterns that are applicable to brownfield are:

• Adapter Pattern – adapt a component to another component using a different interface.
• Proxy Pattern – useful for controlling access to some resource, especially remote ones. Allows decoupling of the client from knowledge of connecting to the service.
• (Remote) Façade Pattern – to remove the complexity of some service by providing a simplified interface
• Data Transfer Object – useful in decoupling the views from the data access codes as well as reducing the number of remote invocations to the database layer.
• Data Access Layer – used to isolate the data access from the users’ interface.