What configuration parameters do we pass to the HTTP client (RestTemplate/WebClient/Feign) for calling an external service?

When calling an external service via HTTP clients (RestTemplate, WebClient, Feign), the following parameters are usually configured:

• URL and request path — the address of the called service.
• HTTP method — GET, POST, PUT, DELETE, etc.
• Headers — for example, Authorization for tokens, Content-Type, Accept.
• Request body — for POST/PUT requests, serialized into JSON, XML, etc.
• Query parameters — for GET requests.
• Timeouts — connection and response wait times to prevent hanging.
• Error handling and retries — policy in case of failures.
• Encoding and serialization/deserialization — data format settings.

Example of configuring RestTemplate with timeouts and headers:

HttpHeaders headers = new HttpHeaders();
headers.set("Authorization", "Bearer token");
headers.setContentType(MediaType.APPLICATION_JSON);

HttpEntity<String> entity = new HttpEntity<>(jsonBody, headers);

RestTemplate restTemplate = new RestTemplate();
restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory() {{
    setConnectTimeout(5000);
    setReadTimeout(5000);
}});

ResponseEntity<String> response = restTemplate.exchange(
    "https://api.example.com/resource",
    HttpMethod.POST,
    entity,
    String.class
);

For WebClient and Feign, timeouts, headers, and serialization are configured similarly.