Interfaces

Abstract

We can now start with our example application. The World Cookery website will store information about recipes from around the world. Thus the first thing we need is a component to store recipe information in. As we have discussed in Chapter 2, components that store data are content components. Before we are going to write such a component, we need to define what kind of data it shall store and provide: we need to write an interface!

Interfaces are contracts that define how components work together. They describe the methods and attributes provided by an object. Interfaces describe the what of a component, they do not describe the how. The modelling of interfaces can be tackled many different ways. As we look at these possibilities we will improve the example implementation with each iteration. This process of refactoring occurs a number of times in this book to constantly improve and adjust the code.