Networking: Sockets and HTTP

Socket provides a TCP client endpoint; ServerSocket accepts connections. Protocols need message framing, encoding, size limits, timeouts, authentication, and clean shutdown.

Modern HTTP

HttpClient client = HttpClient.newBuilder()
    .connectTimeout(Duration.ofSeconds(3)).build();
HttpRequest request = HttpRequest.newBuilder(URI.create(url))
    .timeout(Duration.ofSeconds(5)).GET().build();
HttpResponse<String> response = client.send(
    request, HttpResponse.BodyHandlers.ofString(StandardCharsets.UTF_8));

Validate status, content type, redirects, and response size. Async sending returns CompletableFuture. Bound retries with backoff and idempotency awareness. Treat remote input as untrusted, use TLS verification, avoid SSRF by constraining destinations, and close socket streams deterministically.