Building RESTful APIs with Spring Boot

Welcome to the first lesson of the course, "Building RESTful APIs with Spring Boot." This is the second course in our series, and by now, you should be comfortable with concepts like Dependency Injection and Spring Beans. In this course, you'll learn how to build a simple REST API with Spring Boot and Kotlin. If you're unfamiliar with the term REST, don't worry; we’ll explain everything step by step. In this specific lesson, you'll get acquainted with REST, understand its benefits, and see how Spring Boot supports it. You'll also learn about a significant building block of Spring Boot called the controller, and you'll create your first one. Let's dive in!

REST stands for Representational State Transfer. Although it may sound complex, let’s simplify it with a digital recipe book as an example. In our digital recipe book, the most important aspect is the data—the recipes.

Each recipe is a distinct piece of information that you can access, read, modify, or delete. For instance, "Chocolate Chip Cookies" or "Spaghetti Bolognese" are examples of resources within your digital recipe book. In a RESTful web service, resources are identified by URIs (Uniform Resource Identifiers), which act like addresses in your recipe book.

Examples:

• /recipes/cookies could point to the "Chocolate Chip Cookies" recipe.
• /recipes/spaghetti could refer to the "Spaghetti Bolognese" recipe.

When you view or share a recipe, you're interacting with its representation. This could be a list of ingredients and instructions formatted in a specific way. For instance, requesting the "Chocolate Chip Cookies" recipe might yield:

{
  "title": "Chocolate Chip Cookies",
  "ingredients": ["flour", "sugar", "chocolate chips", "butter", "eggs"],
  "instructions": "Mix ingredients, bake at 350°F for 12 minutes."
}

The actual recipe resides on the server, but you work with its representation.

In REST, you manage resources using various HTTP methods, which correspond to actions you want to take on the recipes:

• GET: Retrieve a specific recipe.
  • Example: GET /recipes/cookies retrieves the "Chocolate Chip Cookies" recipe.
• POST: Add a new recipe.
  • Example: POST /recipes could create a new recipe, like "Banana Bread."
• PUT: Update an existing recipe.
  • Example: PUT /recipes/cookies updates the "Chocolate Chip Cookies" recipe.
• DELETE: Remove a recipe.
  • Example: DELETE /recipes/cookies removes the "Chocolate Chip Cookies" recipe from your collection.