In this unit, we will delve into the world of HTTP and REST, two fundamental concepts in the realm of networking. These concepts are crucial for any developer working with web services or APIs.
HTTP, or Hypertext Transfer Protocol, is the foundation of any data exchange on the Web. It is a protocol - a set of rules that dictate how data should be exchanged. HTTP operates as a request-response protocol in the client-server computing model.
A client (a web browser or an app, for example) sends an HTTP request to the server, then the server returns a response to the client. The response contains status information about the request and may also contain the requested content.
HTTP defines a set of request methods, sometimes referred to as HTTP verbs, to indicate the desired action to be performed. The most common methods include:
- GET: Requests data from a specified resource.
- POST: Sends data to a server to create a new resource.
- PUT: Updates a current resource with new data.
- DELETE: Deletes a specified resource.
REST, or Representational State Transfer, is an architectural style for providing standards between computer systems on the web, making it easier for systems to communicate with each other.
REST-compliant systems, often called RESTful systems, are characterized by how they are stateless and separate the concerns of client and server. In a RESTful system, the client is responsible for the user interface and user experience, and the server is responsible for processing requests and sending appropriate responses.
REST has a set of constraints or principles that a system must adhere to, including:
- Client-Server: There should be a separation between the server that stores the information and the client that accesses it.
- Stateless: Each request from a client to a server must contain all the information needed to understand and process the request.
- Cacheable: Responses from the server can be cached by the client to improve performance.
- Uniform Interface: The method of communication between the client and server should be consistent and uniform.
A RESTful API (Application Programming Interface) uses HTTP and REST principles to interact with data. These APIs have become a standard method for businesses and organizations to share data with clients, customers, and partners. They allow different software systems to communicate with each other, even if they are built on different platforms.
In the next unit, we will learn how to make API calls using Swift, which will allow us to retrieve, create, update, and delete data from a server.