Re: [Libevent-users] How http client can send back message to server?

[Christian Dahlqvist <acdahlqvist@xxxxxxxxx>]

I am a bit confused about your description how the flow of messages
between client and server works. It seems like the client is trying to
act as a server once the first request has been sent, which I would
expect would confuse any standard HTTP server. Should the client not
instead send a new request containing the heartbeat acknowledgement
instead of a HTTP response?

Christian

On Fri, Dec 10, 2010 at 5:18 PM, Zulfiqer Sekender <zulfiqers@xxxxxxxxx> wrote:
> Hi,
>
> I have to develop a simple http client which can communicate with a http
> server. The client is sending evhttp_make_request(). The server sends "HT:"
> heartbeat in response after certain time and when the client gets "HT:" each
> time it will send "HA:" as heartbeat acknowledgement. Transfering of "HT:" &
> "HA:" should go on.
>
> I developed the following client program. It gets "HT:" and tries to send
> back "HA:". But server never gets the "HA:".
>
> I will highly appreciate any help regarding this. Please, let me know what
> wrong I am doing and how to do it correctly.  (Intentionally I left few
> commented out lines to show what else options I tried.)
>
> Please, please help me.
>
> Thanks.
>
> Here is the code:
>
>
>
> #include <sys/types.h>
>
> #include <sys/time.h>
>
> #include <sys/queue.h>
>
> #include <stdlib.h>
>
> //#include <err.h>
>
> #include <event.h>
>
> #include <evhttp.h>
>
> #include <unistd.h>
>
> #include <stdio.h>
>
> #include <sys/socket.h>
>
> #include <netinet/in.h>
>
> #include <time.h>
>
> #include <pthread.h>
>
> #include <string.h>
>
>
>
> #define BUFSIZE 4096
>
> #define SERVERADDR "15.172.175.61"
>
> #define SERVERPORT 8070
>
> #define SLEEP_MS 10
>
>
>
> char buf[BUFSIZE];
>
>
>
> int bytes_recvd = 0;
>
> int chunks_recvd = 0;
>
> int closed = 0;
>
> int connected = 0;
>
>
>
> // called per chunk received
>
> void chunkcb(struct evhttp_request * req, void * arg)
>
> {
>
>     int s = evbuffer_remove( req->input_buffer, &buf, BUFSIZE );
>
>     printf("Read %d bytes: %s\n", s, &buf);
>
>     bytes_recvd += s;
>
>     chunks_recvd++;
>
>     if (strcmp(buf,"HT:") == 0)
>
>     {
>
>       struct evbuffer *evbuff = NULL;
>
>       evbuff = evbuffer_new();
>
>       evbuffer_add_printf(evbuff,"HA:");
>
>       evbuffer_add_printf(req->output_buffer,"HA:");
>
>      // evhttp_send_reply_start(req, HTTP_OK, "Start");
>
>       evhttp_send_reply_chunk(req, evbuff);
>
>       // evhttp_send_reply_chunk(req,"3/r/nHA:/r/n");
>
>      // evhttp_send_reply(req, HTTP_OK, "", evbuff);
>
>      // evhttp_send_reply(req, HTTP_OK, "Response","3/r/nHA:/r/n" );
>
>      // evhttp_send_reply(req, HTTP_OK, "Response",NULL);
>
>       // evhttp_send_reply_end(req);
>
>       evbuffer_free(evbuff);
>
>     }
>
> }
>
>
>
> // gets called when request completes
>
> void reqcb(struct evhttp_request * req, void * arg)
>
> {
>
>     closed++;
>
>     printf("\nClosed.\n");
>
> }
>
>
>
> int main(int argc, char **argv)
>
> {
>
>     event_init();
>
>     struct evhttp *evhttp_connection;
>
>     struct evhttp_request *evhttp_request;
>
>     char addr[16];
>
>     char path[3200]; // eg: "/test/123"
>
>     sprintf(&addr, "12.176.173.18");
>
>     evhttp_connection = evhttp_connection_new(SERVERADDR, SERVERPORT);
>
>     if (evhttp_connection == NULL)
>
>     {
>
>             printf("New connection failed\n");
>
>             break;
>
>     }
>
>     evhttp_connection_set_local_address(evhttp_connection, &addr);
>
>     evhttp_set_timeout(evhttp_connection, 864000); // 10 day timeout
>
>     evhttp_request = evhttp_request_new(reqcb, NULL);
>
>     evhttp_request->chunk_cb = chunkcb;
>
>     evhttp_request->chunked = 1; // Chunked
>
>     evhttp_add_header(evhttp_request->output_headers, "Transfer-Encoding",
> "chunked");
>
>     sprintf(&path, "/test/123");
>
>     evhttp_make_request( evhttp_connection, evhttp_request, EVHTTP_REQ_POST,
> path );
>
>     evhttp_connection_set_timeout(evhttp_request->evcon, 864000);
>
>     event_loop( EVLOOP_NONBLOCK );
>
>     usleep(SLEEP_MS*1000);
>
>     event_dispatch();
>
>     return 0;
>
> }
>
>
>
>
>
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