Menu Search

Chapter 2. Using the Qpid Messaging API

The Qpid Messaging API is quite simple, consisting of only a handful of core classes.

  • A message consists of a standard set of fields (e.g. subject, reply-to), an application-defined set of properties, and message content (the main body of the message).

  • A connection represents a network connection to a remote endpoint.

  • A session provides a sequentially ordered context for sending and receiving messages. A session is obtained from a connection.

  • A sender sends messages to a target using the sender.send method. A sender is obtained from a session for a given target address.

  • A receiver receives messages from a source using the receiver.fetch method. A receiver is obtained from a session for a given source address.

The following sections show how to use these classes in a simple messaging program.

2.1. A Simple Messaging Program in C++

The following C++ program shows how to create a connection, create a session, send messages using a sender, and receive messages using a receiver.

Example 2.1. "Hello world!" in C++

	#include <qpid/messaging/Connection.h>
	#include <qpid/messaging/Message.h>
	#include <qpid/messaging/Receiver.h>
	#include <qpid/messaging/Sender.h>
	#include <qpid/messaging/Session.h>

	#include <iostream>

	using namespace qpid::messaging;

	int main(int argc, char** argv) {
	std::string broker = argc > 1 ? argv[1] : "localhost:5672";
	std::string address = argc > 2 ? argv[2] : "amq.topic";
	std::string connectionOptions = argc > 3 ? argv[3] : "";

	Connection connection(broker, connectionOptions);
	try {
        connection.open();  (1)
        Session session = connection.createSession(); (2)

        Receiver receiver = session.createReceiver(address); (3)
        Sender sender = session.createSender(address); (4)

        sender.send(Message("Hello world!"));

        Message message = receiver.fetch(Duration::SECOND * 1); (5)
        std::cout << message.getContent() << std::endl;
        session.acknowledge(); (6)

        connection.close(); (7)
        return 0;
	} catch(const std::exception& error) {
        std::cerr << error.what() << std::endl;
        connection.close();
        return 1;
	}
	}

(1)

Establishes the connection with the messaging broker.

(2)

Creates a session object on which messages will be sent and received.

(3)

Creates a receiver that receives messages from the given address.

(4)

Creates a sender that sends to the given address.

(5)

Receives the next message. The duration is optional, if omitted, will wait indefinitely for the next message.

(6)

Acknowledges receipt of all fetched messages on the session. This informs the broker that the messages were transferred and processed by the client successfully.

(7)

Closes the connection, all sessions managed by the connection, and all senders and receivers managed by each session.