Overview

The controller is a Java program that is used to glue UI (view) and Data (model) together.

A simple UI does not require any controllers. For example, the data of a Listbox could be abstracted by implementing ListModel.

For typical database access, the glue logic (i.e., control) can be handled by a generic feature called Data Binding. In other words, the create, read, update and delete operations (CRUD) can be handled automatically by a generic Data Binding, and you don't need to write the glue logic at all.

In this section we will discuss how to implement a custom controller (which is called a composer in ZK terminology).