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nng_http_client_transact(3http)

NAME

nng_http_client_transact - perform one HTTP transaction

SYNOPSIS

#include <nng/nng.h>
#include <nng/supplemental/http/http.h>

void nng_http_client_transact(nng_http_client *client, nng_http_req *req,
    nng_http_res *res, nng_aio *aio);

DESCRIPTION

The nng_http_client_transact() function is used to perform a complete HTTP exchange. It creates a new connection using client, performs the transaction by sending the request req (and attached body data) to the remote server, then reading the response res, and finally closes the connection that it created. The entire response is read, including any associated body, which can subsequently be obtained using nng_http_res_get_data().

This function is intended to make creation of client applications easier, by performing multiple asynchronous operations required to complete an entire HTTP transaction.

A similar function, nng_http_conn_transact(), exists. That function behaves similarily, but uses an existing connection, which can be reused.

Note
 This function does not support reading data sent using chunked transfer encoding, and if the server attempts to do so, the underlying connection will be closed and an NNG_ENOTSUP error will be returned. This limitation is considered a bug, and a fix is planned for the future.
Warning
 If the remote server tries to send an extremely large buffer, then a corresponding allocation will be made, which can lead to denial of service attacks. Client applications should take care to use this only with reasonably trust-worthy servers.

This function returns immediately, with no return value. Completion of the operation is signaled via the aio, and the final result may be obtained via nng_aio_result(). That result will either be zero or an error code.

RETURN VALUES

None.

ERRORS

NNG_ECANCELED

The operation was canceled.
NNG_ECLOSED

The connection was closed.
NNG_ECONNRESET

The peer closed the connection.
NNG_ENOMEM

Insufficient free memory to perform the operation.
NNG_ENOTSUP

HTTP operations are not supported, or peer sent chunked encoding.
NNG_EPROTO

An HTTP protocol error occurred.
NNG_ETIMEDOUT

Timeout waiting for data from the connection.