# nng_http_conn_transact(3http) Manual Page

## NAME

nng_http_conn_transact - perform one HTTP transaction on connection

## SYNOPSIS

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

    void nng_http_conn_transact(nng_http_conn *conn, nng_http_req *req,
        nng_http_res *res, nng_aio *aio);

## DESCRIPTION

The `nng_http_conn_transact()` function is used to perform a complete HTTP exchange over the connection conn, sending the request req (and attached body data) to the remote server, and reading the response res. 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.

If an error occurs, the caller should close conn with `nng_http_conn_close()`, as it may not necessarily be usable with other transactions.

A similar function, `nng_http_client_transact()`, exists. That function behaves similarily, but creates a connection on demand for the transaction, and disposes of it when finished.

| 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.

| A given connection conn should be used with only one operation or transaction at a time as HTTP/1.1 has no support for request interleaving.

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.
`NNG_EPROTO` | An HTTP protocol error occurred.
`NNG_ETIMEDOUT` | Timeout waiting for data from the connection.

## SEE ALSO

nng_aio_alloc(3), nng_aio_result(3), nng_strerror(3), nng_http_client_connect(3http), nng_http_client_transact(3http), nng_http_conn_read_res(3http), nng_http_conn_read_all(3http), nng_http_conn_write_req(3http), nng_http_res_get_data(3http), nng(7)