#SignalR.RabbitMq

#About

SignalR.RabbitMq is an implementation of an ScaleOutMessageBus using RabbitMq as the backing store. This allows a signalr web application to be scaled across a web farm.

#Installation

.Net

A compiled library is available via NuGet

To install via the nuget package console

Install-Package SignalR.RabbitMq

To install via the nuget user interface in Visual Studio the package to search for is "SignalR.RabbitMq"

RabbitMQ

For the messagebus to work you need to install a custom exchange type via the plugin - rabbitmq-stamp.

A complied version is available in the rabbitmq-plugin folder.

The plugin has been compiled using Erlang R16B.

If your installation uses a previous version of Erlang you will need to recompile the source (or raise a ticket and I'm sure I can sort you out).

To install the plugin please follow the instructions at http://www.rabbitmq.com/plugins.html.

The source of the plugin is available from https://github.com/mdevilliers/rabbitmq-stamp.

If you want to build the plugin from source details are available from https://github.com/mdevilliers/rabbitmq-stamp

#Usage

General Usage

The example web project shows how you could configure the message bus in the global.asax.cs file.

var factory = new ConnectionFactory 
{ 
	UserName = "guest",
	Password = "guest"
};


var exchangeName = "SignalR.RabbitMQ-Example";

var configuration = new RabbitMqScaleoutConfiguration(factory, exchangeName);
GlobalHost.DependencyResolver.UseRabbitMq(configuration);

The SignalR.RabbitMq message bus expects to be handed a RabbitMqScaleoutConfiguration configured with either

• an instance of a configured ConnectionFactory as produced by the RabbitMq.Client.
• an ampq connection string e.g. "host=myServer;virtualHost=myVirtualHost;username=myusername;password=topsecret" and the name of a message exchange to be used for the signalr messages
• a preconfigured EasyNetQ IBus and the name of a message exchange to be used for the signalr messages.

The message bus will then create the exchange if it does not already exist then listen on an anonymous queue for messages across the web farm. There will be one queue per server in the web farm.

It is recommended that each application should specify its own application name.

The message exchange should only be used for signalr messages.

Send to client via message bus

One benefit of using the message bus is to send messages directly to connected clients from another process.

An example -

var factory = new ConnectionFactory 
{ 
	UserName = "guest",
	Password = "guest"
};

var exchangeName = "SignalR.RabbitMQ-Example";

var configuration = new RabbitMqScaleoutConfiguration(factory, exchangeName);
GlobalHost.DependencyResolver.UseRabbitMq(configuration);

var hubContext = GlobalHost.ConnectionManager.GetHubContext<Chat>();

Task.Factory.StartNew(
	() =>
		{
			while (true)
			{
				hubContext.Clients.All.onConsoleMessage("Hello!");
				Thread.Sleep(1000);
			}
		}
	);

The onConsoleMessage method is a javascript function on the client. The message "Hello!" is put onto the message bus and relayed by the web application to the connected clients.

#Advanced

Everyone likes to be in control so if you have a specific requirements on connecting to RabbitMQ or if you need to audit connections or messages you can supply your own class that extends RabbitConnectionBase.

Your class can then be wired up using the other overload -

GlobalHost.DependencyResolver.UseRabbitMqAdvanced(...);

Please see the implementation of EasyNetQRabbitConnection for an example implementation.

#FAQ

The library uses EasyNetQ as a sane wrapper of the RabbitMQ.Client

#Contributers

Thanks to -

kevingorski

baralong

Turtlator

ibirman

dfschwabe

Kntajus

slovely

chrisdrobison

Entroper