# nghttp2_submit_data

## Synopsis

#include <nghttp2/nghttp2.h>

int nghttp2_submit_data(nghttp2_session *session, uint8_t flags, int32_t stream_id, const nghttp2_data_provider *data_prd)

  Submits one or more DATA frames to the stream stream_id. The data to be sent are provided by data_prd. If flags contains `nghttp2_flag.NGHTTP2_FLAG_END_STREAM`, the last DATA frame has END_STREAM flag set.

  This function does not take ownership of the data_prd. The function copies the members of the data_prd.

  This function returns 0 if it succeeds, or one of the following negative error codes:

  `nghttp2_error.NGHTTP2_ERR_NOMEM`

    Out of memory.

  `nghttp2_error.NGHTTP2_ERR_DATA_EXIST`

    DATA or HEADERS has been already submitted and not fully processed yet.

  `nghttp2_error.NGHTTP2_ERR_INVALID_ARGUMENT`

    The stream_id is 0.

  `nghttp2_error.NGHTTP2_ERR_STREAM_CLOSED`

    The stream was already closed; or the stream_id is invalid.

  Note

  Currently, only one DATA or HEADERS is allowed for a stream at a time. Submitting these frames more than once before first DATA or HEADERS is finished results in `nghttp2_error.NGHTTP2_ERR_DATA_EXIST` error code. The earliest callback which tells that previous frame is done is `nghttp2_on_frame_send_callback`. In side that callback, new data can be submitted using `nghttp2_submit_data()`. Of course, all data except for last one must not have `nghttp2_flag.NGHTTP2_FLAG_END_STREAM` flag set in flags. This sounds a bit complicated, and we recommend to use `nghttp2_submit_request()` and `nghttp2_submit_response()` to avoid this cascading issue. The experience shows that for HTTP use, these two functions are enough to implement both client and server.