Chapter 4. Examples

This chapter demonstrates the use of AMQ C++ through example programs.

See the Qpid Proton C++ examples for more sample programs.

Note

The code presented in this guide uses C++11 features. AMQ C++ is also compatible with C++03, but the code will require minor modifications.

4.1. Sending messages

This client program connects to a server using <connection-url>, creates a sender for target <address>, sends a message containing <message-body>, closes the connection, and exits.

Example: Sending messages

#include <proton/connection.hpp>
#include <proton/container.hpp>
#include <proton/message.hpp>
#include <proton/messaging_handler.hpp>
#include <proton/sender.hpp>
#include <proton/target.hpp>

#include <iostream>
#include <string>

struct send_handler : public proton::messaging_handler {
    std::string conn_url_ {};
    std::string address_ {};
    std::string message_body_ {};

    void on_container_start(proton::container& cont) override {
        cont.connect(conn_url_);
    }

    void on_connection_open(proton::connection& conn) override {
        conn.open_sender(address_);
    }

    void on_sender_open(proton::sender& snd) override {
        std::cout << "SEND: Opened sender for target address '"
                  << snd.target().address() << "'\n";
    }

    void on_sendable(proton::sender& snd) override {
        proton::message msg {message_body_};
        snd.send(msg);

        std::cout << "SEND: Sent message '" << msg.body() << "'\n";

        snd.close();
        snd.connection().close();
    }
};

int main(int argc, char** argv) {
    if (argc != 4) {
        std::cerr << "Usage: send <connection-url> <address> <message-body>\n";
        return 1;
    }

    send_handler handler {};
    handler.conn_url_ = argv[1];
    handler.address_ = argv[2];
    handler.message_body_ = argv[3];

    proton::container cont {handler};

    try {
        cont.run();
    } catch (const std::exception& e) {
        std::cerr << e.what() << "\n";
        return 1;
    }

    return 0;
}

Running the example

To run the example program, copy it to a local file, compile it, and execute it from the command line. 

$ g++ send.cpp -o send -std=c++11 -lstdc++ -lqpid-proton-cpp
$ ./send amqp://localhost queue1 hello

4.2. Receiving messages

This client program connects to a server using <connection-url>, creates a receiver for source <address>, and receives messages until it is terminated or it reaches <count> messages.

Example: Receiving messages

#include <proton/connection.hpp>
#include <proton/container.hpp>
#include <proton/delivery.hpp>
#include <proton/message.hpp>
#include <proton/messaging_handler.hpp>
#include <proton/receiver.hpp>
#include <proton/source.hpp>

#include <iostream>
#include <string>

struct receive_handler : public proton::messaging_handler {
    std::string conn_url_ {};
    std::string address_ {};
    int desired_ {0};
    int received_ {0};

    void on_container_start(proton::container& cont) override {
        cont.connect(conn_url_);
    }

    void on_connection_open(proton::connection& conn) override {
        conn.open_receiver(address_);
    }

    void on_receiver_open(proton::receiver& rcv) override {
        std::cout << "RECEIVE: Opened receiver for source address '"
                  << rcv.source().address() << "'\n";
    }

    void on_message(proton::delivery& dlv, proton::message& msg) override {
        std::cout << "RECEIVE: Received message '" << msg.body() << "'\n";

        received_++;

        if (received_ == desired_) {
            dlv.receiver().close();
            dlv.connection().close();
        }
    }
};

int main(int argc, char** argv) {
    if (argc != 3 && argc != 4) {
        std::cerr << "Usage: receive <connection-url> <address> [<message-count>]\n";
        return 1;
    }

    receive_handler handler {};
    handler.conn_url_ = argv[1];
    handler.address_ = argv[2];

    if (argc == 4) {
        handler.desired_ = std::stoi(argv[3]);
    }

    proton::container cont {handler};

    try {
        cont.run();
    } catch (const std::exception& e) {
        std::cerr << e.what() << "\n";
        return 1;
    }

    return 0;
}

Running the example

To run the example program, copy it to a local file, compile it, and execute it from the command line. 

$ g++ receive.cpp -o receive -std=c++11 -lstdc++ -lqpid-proton-cpp
$ ./receive amqp://localhost queue1