sandbox / mbed-http

HTTP and HTTPS library for Mbed OS 5

Dependents:   MQTTGateway2 MQTTGatewayK64 http-example-wnc GuardRoom ... more

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Table of Contents

  1. HTTP Request API
  2. HTTPS Request API
  3. Dealing with large body
  4. Tested on

For the example program, see: sandbox/http-example.

This library is used to make HTTP and HTTPS calls from mbed OS 5 applications.

HTTP Request API

NetworkInterface* network = /* obtain a NetworkInterface object */

const char body[] = "{\"hello\":\"world\"}";

HttpRequest request(network, HTTP_POST, "http://httpbin.org/post");
request.set_header("Content-Type", "application/json);
HttpResponse* response = request.send(body, strlen(body));
// if response is NULL, check response->get_error()

printf("status is %d - %s\n", response->get_status_code(), response->get_status_message());
printf("body is:\n%s\n", response->get_body().c_str());

HTTPS Request API

// pass in the root certificates that you trust, there is no central CA registry in mbed OS
const char SSL_CA_PEM[] = "-----BEGIN CERTIFICATE-----\n"
    /* rest of the CA root certificates */;

NetworkInterface* network = /* obtain a NetworkInterface object */

const char body[] = "{\"hello\":\"world\"}";

HttpsRequest request(network, SSL_CA_PEM, HTTP_GET "https://httpbin.org/status/418");
HttpResponse* response = request.send();
// if response is NULL, check response->get_error()

printf("status is %d - %s\n", response->get_status_code(), response->get_status_message());
printf("body is:\n%s\n", response->get_body().c_str());

Dealing with large body

By default the library will store the full request body on the stack. This works well for small responses, but you'll run out of memory when receiving a large response body. To mitigate this you can pass in a callback as the last argument to the request constructor. This callback will be called whenever a chunk of the body is received. You can set the request chunk size in the HTTP_RECEIVE_BUFFER_SIZE macro (see mbed_lib.json for the definition).

void body_callback(const char* data, size_t data_len) {
    // do something with the data
}

HttpRequest req(network, HTTP_GET, "http://pathtolargefile.com");

Tested on

  • K64F with Ethernet.
  • NUCLEO_F411RE with ESP8266.
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