How to: Habari Client for RabbitMQ evaluation with CloudAMQP

Habari Client for RabbitMQ is a library for Delphi and Free Pascal which provides access to the RabbitMQ open source message broker. Habarisoft offers example aplications for this client library including chat and performance tests, which need an installation of RabbitMQ. But while the RabbitMQ server installation itself is very simple, it also requires an installed Erlang run time environment, and so the preparing steps for client library evaluation take some time.

Fortunately, there is an easy way to avoid the RabbitMQ installation: CloudAMQP, a service which provides managed RabbitMQ servers in the cloud.

After a simple registration, clients can connect to the server using various standard protocols (AMQP, MQTT, STOMP). The CloudAMQ console page displays a connection URL for AMQP connections, which can be used with Habari Client for RabbitMQ chat application after small changes.

A valid URL for the Habari Chat demo application for CloudAMQP has the form stomp://<Server>?connect.host=<VHost>.

Example:

stomp://spotted-monkey.rmq.cloudamqp.com?connect.host=qwerty

Connection configuration

 

 

 

 

 

With the free CloudAMQP plan you can use up to three connections (chat applications) simultaneously.

Habari Client for RabbitMQ

ActiveMQ, Qpid, HornetQ and RabbitMQ in Comparison

An article by Thomas Beyer (also available in German language) gives a short introduction into popular messaging solutions which are available as free open source projects.

“Newer architectures and the standardized AMQP protocol have led to a flood of message brokers. All brokers take claim to be fast, robust and reliable. But what really distinguish the broker? How do I choose the right broker? Should we continue to use established brokers such as the ActiveMQ or try a more modern one? This article attempts to answer these questions and help the reader in selecting a suitable broker.”

Article URL: http://predic8.com/activemq-hornetq-rabbitmq-apollo-qpid-comparison.htm

Apache ActiveMQ 5.10.0 released

Apache ActiveMQ 5.10.0 resolves more than 234 issues, mostly bug fixes and improvements. It has the following new features:

  • Java 8 support
  • Apache Shiro Security Plugin – http://activemq.apache.org/shiro.html
  • Hardened MQTT support
  • Hardened AMQP support
  • Hardened LevelDB store
  • Improved RAR/JCA adapter
  • Improved Runtime configuration plugin
  • Improved Web console

Source: http://activemq.apache.org/activemq-5100-release.html

A Delphi and Free Pascal STOMP based client library is available from Habarisoft.

Habari Client Libraries

 

RabbitMQ use cases: NYTimes

Michael Laing, a Systems Architect at NYTimes, gave a great decription of their use of RabbitMQ and their overall architecture on the RabbitMQ mailing list, which later also appeared on High Scalability –  NYTimes Architecture: No Head, No Master, No Single Point of Failure

We use Rabbit MQ as our message passing system. Right now, the messages we handle are things like Breaking News Alerts and Live Video alerts. Our internal clients send the fabrik these messages over AMQP. We then send them around our stack, ensuring they are delivered.

We have Rabbit in all layers of our stack, with shovels connecting them. Our own internal code helps route the messages based on there services level. Some messages, like Breaking News, must go out as quickly as possible. So we spread these out over out clusters AND shovel them to clusters in other regions for processing. From there the messages get send to the front end for delivery.

We also use Rabbit for individual messages. If you are a registered NYTimes users, we can send you personally a message. Things like credit card expiring.

 

Query ActiveMQ Broker Statistics with Delphi

Broker Configuration

To configure ActiveMQ to use the statistics plugin add the following to the ActiveMQ XML configuration:

<plugins>
  <statisticsBrokerPlugin/>
</plugins>

The statistics plugin looks for messages sent to particular destinations.

Query running broker statistics

To query the running statistics of the message broker, the client sends an empty message to a Destination named ActiveMQ.Statistics.Broker, and sets the replyto field with the Destination you want to receive the result on. The statistics plugin will send a  MapMessage filled with the statistics for the running ActiveMQ broker.

Source code

program DestStatistics;

(**
  Requires ActiveMQ 5.3 or higher
  To configure ActiveMQ to use the statistics plugin, add the following to the ActiveMQ XML configuration:
  <broker>
  ...
    <plugins>
      <statisticsBrokerPlugin/>
    </plugins>
  ...
  </broker>

  Usage:
  ------
  DestStatistics [destination]
  If no destination is specified, the program returns the broker statistics

  Reference
  ---------

http://activemq.apache.org/statisticsplugin.html


https://issues.apache.org/activemq/browse/AMQ-2379


http://rajdavies.blogspot.com/2009/10/query-statistics-for-apache-activemq.html

  You can also use wildcards too, and receive a separate message for every destination matched.
*)

{$APPTYPE CONSOLE}

uses
  SysUtils,
  BTCommAdapterIndy, BTMessageTransformerXMLMapOmni,
  BTJMSInterfaces, BTJMSConnection, BTSessionIntf, BTSerialIntf,
  BTStompTypes, BTTypes,
  Classes;

var
  Connection: IConnection;
  Session: ISession;
  Producer: IMessageProducer;
  Consumer: IMessageConsumer;
  Destination, ReplyQueue: IQueue;
  JMSMessage: ITextMessage;
  Reply: IMapMessage;
  MapNames: PMStrings;
  I: Integer;
  Key: string;

begin
  Connection := TBTJMSConnection.MakeConnection;
  try
    try
      // Create and assign the message transformer
      SetTransformer(Connection, TBTMessageTransformerXMLMapOmni.Create(nil));

      Connection.Start;
      Session := Connection.CreateSession(False, amAutoAcknowledge);

      // listen on reply queue
      ReplyQueue := Session.CreateQueue('Habari' + '?' +
        BTStompTypes.SH_TRANSFORMATION + '=' + TRANSFORMER_ID_MAP_XML);
      Consumer := Session.CreateConsumer(ReplyQueue);

      // create the pseudo destination
      if ParamCount = 0 then
      begin
        Destination := Session.CreateQueue('ActiveMQ.Statistics.Broker');
      end
      else
      begin
        Destination := Session.CreateQueue('ActiveMQ.Statistics.Destination.' + ParamStr(1));
      end;

      // display destination name
      WriteLn('Request statistics for ' + Destination.QueueName + ' ...');

      // create the message and set reply queue name
      JMSMessage := Session.CreateTextMessage;
      JMSMessage.JMSReplyTo := ReplyQueue;
      Producer := Session.CreateProducer(Destination);
      Producer.Send(JMSMessage);

      // read the result message
      Reply := Consumer.Receive(1000) as IMapMessage;

      // list the map key/values
      while Assigned(Reply) do
      begin
        MapNames := Reply.GetMapNames;
        for I := 0 to Length(MapNames) - 1 do
        begin
          Key := MapNames[I];
          WriteLn(Key + '=' + Reply.GetString(Key));
        end;
        WriteLn;
        Reply := Consumer.Receive(1000) as IMapMessage;
      end;

      WriteLn('No more message on queue ' + ReplyQueue.QueueName);

      Connection.Stop;

    except
      on E: Exception do
        WriteLn(E.Message);
    end;
  finally
    Connection.Close;
  end;

  WriteLn('Press any key');
  ReadLn;
end.

 


Query Statistics for Apache ActiveMQ with Delphi

RabbitMQ 3.3.1 free open source message broker released

The RabbitMQ team announced the release of RabbitMQ 3.3.1. This release fixes a number of bugs in 3.3.0 and earlier versions, including security bugs in the MQTT and shovel plugins. Binary and source distributions of the new release can be found on the download page.

For application integration in Delphi and Free Pascal, Habarisoft offers a commercial client library for RabbitMQ 3.2.4 and newer.

Habari Web Components 2.8 released

The new release 2.8 of the web application framework for Delphi and Free Pascal is available now. Changes include:

  • FPCUnit test project
  • validation of context names and mappings
  • new tutorials with source code
  • updated Flightplan demo for jQuery Mobile
  • Log4D (logging framework) source code workarounds for Free Pascal

Flightplan Demo (using jQuery Mobile 1.4.2)

DUnit and FPCUnit Tests

FPCUnit Tests

About

Habari Web Components is a web application framework for small to medium size HTTP services, based on the popular open source TCP/IP library for Delphi and Free Pascal, Internet Direct (Indy). If you like to see it in action, download and run the off-line demo applications, or go to the on-line demo. Need more information? Browse the on-line API documentation, or read the Getting Started document.

  • supports Delphi 2009 and Free Pascal 2.6.0 or newer with Internet Direct (Indy) 10.6
  • full source code included, with DUnit/FPCUnit tests and example applications
  • redistribution with your application does not require any additional fees
  • free updates for one year

Example source code for Hello World web component

This web component answers HTTP GET requests with a hello world response (content type text/plain). The full tutorial project code is included in the demo download.

unit HelloWorldResource;

interface

uses djWebComponent, IdCustomHTTPServer;

type
  THelloWorldResource = class(TdjWebComponent)
  public
    procedure OnGet(
      Request: TIdHTTPRequestInfo;
      Response: TIdHTTPResponseInfo); override;
  end;

implementation

procedure THelloWorldResource.OnGet(
  Request: TIdHTTPRequestInfo;
  Response: TIdHTTPResponseInfo);
begin
  Response.ContentText := 'Hello world!';
  Response.ContentType := 'text/plain';
end;

end.

 

Habari Web Components