Tutorial

This tutorial consists of a series of examples using the three most commonly used exchange types - Direct, Fanout and Topic
exchanges. These examples show how to write applications that use the most common messaging paradigms.

• direct
  In the direct examples, a message producer writes to the direct exchange, specifying a routing key. A message consumer reads messages from a named queue. This illustrates clean separation of concerns - message producers need to know only the exchange and the routing key, message consumers need to know only which queue to use on the broker.
• fanout
  The fanout examples use a fanout exchange and do not use routing keys. Each binding specifies that all messages for a given exchange should be delivered to a given queue.
• pub-sub
  In the publish/subscribe examples, a publisher application writes messages to an exchange, specifying a multi-part key. A subscriber application subscribes to messages that match the relevant parts of these keys, using a private queue for each subscription.
• request-response
  In the request/response examples, a simple service accepts requests from clients and sends responses back to them. Clients create their own private queues and corresponding routing keys. When a client sends a request to the server, it specifies its own routing key in the reply-to field of the request. The server uses the client's reply-to field as the routing key for the response.

Running the Examples

Before running the examples, you need to unzip the file Qpid.NET-net-2.0-M4.zip, the following tree is created:

<home>
  |-qpid
     |-lib (contains the required dlls)
     |-examples
          |- direct
          |    |-example-direct-Listener.exe
          |    |-example-direct-Producer.exe
          |- fanout
          |    |-example-fanout-Listener.exe
          |    |-example-fanout-Producer.exe
          |- pub-sub
          |    |-example-pub-sub-Listener.exe
          |    |-example-pub-sub-Publisher.exe
          |- request-response
               |-example-request-response-Client.exe
               |-example-request-response-Server.exe

Make sure your PATH contains the directory <home>/qpid/lib
The examples can be run by executing the provided exe files:

$ cd <home>/qpid/examples/examplefolder
$ example-...-.exe

Creating and Closing Sessions

All of the examples have been written using the Apache Qpid .NEt 0.10 API. The examples use the same skeleton code to initialize the program, create a session, and clean up before exiting:

using System;
using System.IO;
using System.Text;
using System.Threading;
using org.apache.qpid.client;
using org.apache.qpid.transport;

...

        private static void Main(string[] args)
        {
            string host = args.Length > 0 ? args[0] : "localhost";
            int port = args.Length > 1 ? Convert.ToInt32(args[1]) : 5672;
            Client connection = new Client();
            try
            {
                connection.connect(host, port, "test", "guest", "guest");
                ClientSession session = connection.createSession(50000);

                //--------- Main body of program --------------------------------------------

                connection.close();
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: \n" + e.StackTrace);
            }
        }
...

Writing Direct Applications

This section describes two programs that implement direct messaging using a Direct exchange:
• org.apache.qpid.example.direct.Producer (from example-direct-producer) publishes messages to the amq.direct exchange, using the routing key routing_key.
•org.apache.qpid.example.direct.Listener (from example-direct-Listener) uses a message listener to receive messages from the queue named message_queue.

Running the Direct Examples

1) Make sure your PATH contains the directory <home>/qpid/lib

2) Make sure that a qpid broker is running:

$ ps -eaf | grep qpidd

If a broker is running, you should see the qpidd process in the output of the above
command.

3) Publish a series of messages to the amq.direct exchange by running direct producer, as follows:

$ cd <home>/qpid/examples/direct

With cygwin:

$ ./example-direct-Producer.exe  

or with mono:

$ mono ./example-direct-Producer.exe

This program has no output; the messages are routed to the message queue, as instructed by the binding.

4) Read the messages from the message queue using direct consumer or listener, as follows:

$ cd <home>/qpid/examples/direct

With cygwin:

$ ./example-direct-Listener.exe  

or with mono:

$ mono ./example-direct-Listener.exe

You should see the following output:

Message: Message 0
Message: Message 1
Message: Message 2
Message: Message 3
Message: Message 4
Message: Message 5
Message: Message 6
Message: Message 7
Message: Message 8
Message: Message 9
Message: That's all, folks!
Shutting down listener for message_queue

Now we will examine the code for each of these programs. In each section, we will discuss only
the code that must be added to the skeleton shown in Section "Creating and Closing Sessions".