How can you use the delegation design pattern in web application development?

1 What is delegation?

Delegation is a design pattern that allows an object to delegate some of its responsibilities to another object, without exposing the details of how the delegation is done. This way, the delegating object can focus on its core functionality, while the delegate object can handle the specific tasks that vary depending on the context. For example, in a web application, you might have a controller object that delegates the rendering of the user interface to a view object, or a service object that delegates the data access to a repository object.

2 Why use delegation?

Delegation can be incredibly beneficial for web application development, as it reduces coupling and increases cohesion, thus making code more modular and easier to test, reuse, and extend. It also enhances flexibility and adaptability, allowing developers to modify the behavior of a web application by replacing or modifying delegate objects without affecting the delegating objects. Furthermore, delegation promotes separation of concerns and the single responsibility principle, leading to code that is more readable and maintainable, as each object has a clear and distinct role.

4 Example of delegation

To illustrate how the delegation design pattern works in web application development, let's look at a simple example. Suppose you have a web application that allows users to upload and download files from a cloud storage service, such as Google Drive, Dropbox, or OneDrive. A possible solution is to use the delegation design pattern. This involves creating a StorageService class that represents the common functionality of uploading and downloading files from any storage provider, as well as a StorageProvider interface that defines the methods for connecting, uploading, and downloading files from a specific storage provider. Additionally, GoogleDriveProvider, DropboxProvider, and OneDriveProvider classes should be created to implement the StorageProvider interface and provide the concrete logic for interacting with each storage provider. The appropriate StorageProvider object should then be injected into the StorageService object depending on the user's preference or configuration. This is done by calling the StorageProvider methods from the StorageService methods. In this way, you can inform and reassure stakeholders while providing valuable insights for improving your cloud security posture. Here is a simplified code example in Java demonstrating this approach.