Qpid Proton client using the engine API not sending message to server

Question

I am trying to write an AMQP 1.0 client using Qpid Proton in C. I do not want to use messenger. I want to use the proton-c engine. I am having a little trouble figuring out how to do this. My main sticking point is setting the endpoint for the connection. The only example of a C client using the proton-c engine I can find is here.

https://github.com/apache/qpid-proton/blob/master/examples/engine/c/psend.c

However, it uses structs that are not part of the Qpid Proton C API 0.12.0. Specifically, I don’t see pn_driver_t or pn_connector_t as part of the 0.12.0 API.

I am trying to follow the general workflow defined in the AMQP 1.0 spec 1) create a connection, 2) create a session, 3) create a sender link. I am not very experienced with C and this is my first time using the non-messenger part of the Qpid Proton library so forgive me if I missed something obvious. Here is my current code. I have been trying different options and searching for days.

#include <stdio.h>
#include <unistd.h> 
#include <string.h>
#include "proton/message.h"
#include "proton/messenger.h"
#include "proton/connection.h"
#include "proton/session.h"
#include "proton/link.h"
#include "proton/delivery.h"
#include "proton/event.h"
#include "proton/engine.h"

//State integer values are defined in Connection macros
//https://qpid.apache.org/releases/qpid-proton-0.12.0/proton/c/api/group__connection.html
void print_state(char * name, pn_state_t state)
{
    printf("[%s] local: %i, remote: %i\n", name, PN_LOCAL_MASK & state, PN_REMOTE_MASK & state);
}

//Reference https://github.com/apache/qpid-proton/blob/master/examples/engine/c/psend.c
void send_engine()
{
    struct pn_connection_t * connection;
    connection = pn_connection();
    //STACKOVERFLOW - I have a feeling this is not right, but cannot find an alternative to set protocol (amqp or ws) the hostname and port. I see a way to set the hostname only
    pn_connection_set_container(connection, "amqp://amqpserver:port");
    print_state("Connection Initialized", pn_connection_state(connection));

    pn_transport_t * transport;
    transport = pn_transport();
    int r = pn_transport_bind(transport, connection);
    if (r != 0)
    {
        printf("transport bind error: %i\n", r);
    }

    pn_connection_open(connection);
    print_state("Connection Opened", pn_connection_state(connection));

    pn_session_t * sess;
    sess = pn_session(connection);
    print_state("Session Initialized", pn_session_state(sess));

    pn_session_open(sess);
    print_state("Session Opened", pn_session_state(sess));

    pn_link_t * sender;
    sender = pn_sender(sess, "c-client");
    //the queue name in "toserver"
    pn_terminus_set_address(pn_link_target(sender), "toserver");
    print_state("Sender Link Initialized", pn_link_state(sender));

    pn_link_open(sender);
    print_state("Sender Link Opened", pn_link_state(sender));

    pn_delivery_t *delivery;
    char *tagID = "uid";
    delivery = pn_delivery(sender, pn_dtag(tagID, strlen(tagID)));

    char *msg = "abc";
    printf("%zd\n", pn_link_send(sender, msg, strlen(msg)));
    pn_delivery_settle(delivery);
    printf("Delivery stettled %d\n", pn_delivery_settled(delivery));

    print_state("Connection End", pn_connection_state(connection));
    print_state("Session End", pn_session_state(sess));
    print_state("Sender Link End", pn_link_state(sender));

    //TODO free everything
}

int main (int argc, char *argv[])
{
    send_engine();
    printf("done\n");
    return 0;
}

On my AMQP server I have enable frame level tracing and do not see any communication from the client. This is not a problem with the server. It works with many other clients, including a C client using the messenger API. What am I missing in this sample? Thank you!

Note: I have tried to solve this exhaustively and provided as much context as possible.

Answer 1

The driver API was removed in Apache Qpid Proton release 0.9 in March, 2015.

commit 4b53bfca06432e440c95d60648b5e7be54ae4296 Author: Rafael Schloming Date: Fri Feb 13 08:27:23 2015 -0500

removed driver API and bindings

C code examples in Proton are Messenger based.

A lot of recent work has gone into a reactor-based C++ implementation that is not Messenger based. See release 0.12.1 documentation for more details and examples.