Reviewing source code in Vapor boilerplate

The following diagram gives you an overview of the boilerplate generated from Vapor's default template:

The Package.swift is used by Swift Package Manager during build time to configure your project's package. The package description comprises essential information such as application name, dependencies on other packages, and different build targets supported in your project.

There are three modules in the project: helloWorld, App, and AppTests. (The diagram only shows the helloWorld and App modules, but the AppTests module will be soon reviewed in the next chapter.) The functions and classes in the files in helloWorld and App modules are invoked in the following order:

1. The helloWorld executable contains a single entry point in main.swift that calls app() to create an application instance and invokes the instance's run...