What methods exist for sending data from client to…

At the HTTP protocol level, the main methods for sending data from client to server:

GET: Sends data in the URL as parameters. Suitable for requests that do not change the server state (retrieving information). Data size is limited and can be cached.
POST: Sends data in the request body. Suitable for sending large volumes of data and data that change the server state (creation, update). Data is not visible in the URL and is not cached by default.
PUT: Sends data to create or update a resource at the specified URL. It is idempotent (multiple calls have no side effects after the first successful one).
DELETE: Sends a request to delete a resource at the specified URL. It is idempotent.
PATCH: Sends data for partial update of a resource. It is not idempotent.

At the implementation level in Java:

HTML forms (POST, GET): Traditional way of sending data from web pages. <form method="POST" action="/submit">...</form>

AJAX (Asynchronous JavaScript and XML): Allows sending HTTP requests from the browser without reloading the page. Uses XMLHttpRequest objects or Fetch API.

// Example with Fetch API
fetch('/submit', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({ data: 'some data' })
})
.then(response => response.json())
.then(data => console.log(data));

Java API: Java applications can use various libraries to send HTTP requests:

java.net.HttpURLConnection (standard API)
Apache HttpClient
OkHttp
Spring RestTemplate / WebClient

// Example with HttpURLConnection
URL url = new URL("http://example.com/submit");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true); // Allow sending data in the request body
try (OutputStream os = con.getOutputStream()) {
    byte[] input = "data=some data".getBytes("utf-8");
    os.write(input, 0, input.length);
}
// ... reading response

REST APIs: Widely used approach for interaction between client and server based on HTTP methods.
WebSocket: Provides a full-duplex connection between client and server, allowing data to be sent in both directions at any time. Suitable for real-time data exchange applications.
gRPC: High-performance RPC (Remote Procedure Call) framework using HTTP/2 and Protocol Buffers.
MQ (Message Queues): Asynchronous way of sending messages between applications (e.g., RabbitMQ, Kafka). The client sends a message to the queue, and the server consumes it.

The choice of method depends on the type of application, data size, speed requirements, and how data is processed on the backend (synchronously/asynchronously).

What methods exist for sending data from client to server?