NServiceBus and SignalR

Background

Having the distributed possibilities with NServiceBus in an event driven architecture and not taking it all the way to the client in a web application is just not good enough. We know that we can rely on NServiceBus for the messaging between servers and processes. SignalR is really an amazing candidate of enabling that next step. It is a bit rough but it is maturing every day and has an active community. I felt it was time to sort things out regarding NServiceBus and SignalR and how they interact. And to provide an example as well. I needed to do this for myself, but I hope that other people can find this useful as well.

Points of interest

This is a really simple sample and no detail has gone into any of the parts. The purpose to provide easy understanding of configuration of the two frameworks and the interactions between them.

Web Application

This is a ASP.NET MVC 4 Web Site from the basic template. The Web App has a simple page where three scenarios are demonstrated:

Hub

This is a standard Hub in SignalR. What I do in one browser gets sent to all the others (in this case). There's nothing special with this case.

From outside of the Hub

This scenario is used when code outside of the Hub want to make use of the Hub connection and call methods on the client. This is our first step towards letting an NServiceBus handler calling clients.

NServiceBus handler using Hub

This scenario completes the circle. There are two ways to send messages. The first sends messages to the Console App where they are diplayed. The console app can also send messages to the client. It's like a chat. The second way is a loopback mechanism where the web sends a message to itself. This is in case you don't want to use the Console App at all.

Added packages:

• NServiceBus 3.3.5
• SignalR 1.0.0-rc2-130116 (from here)
• jQuery 1.9.1

ConsoleApp

This is a very simple Console Application. The purpose is just to show that it is possible to send messages from a separate (server) process to the client (GUI even).

Added packages:

• NServiceBus 3.3.5

Other interesting things

Dependency injection

I wanted to add dependency injection to this as that is what I use myself. I have used Structuremap for this. The use case is simple. I want to be able to inject whatever component into Hubs.

Calling the Hub from another process.

Say you want to call a Hub from a different process. [NotifyMessageReceived] (src/NServiceBusSignalR.ConsoleApp/NotifyReceivedMessage.cs) does this using a [HubProxy] (src/NServiceBusSignalR.ConsoleApp/MessageHubProxy.cs).

Installation

You should be able to just fork the project and run the solution. But here are some things off the top of my head:

• If you haven't run NServiceBus on the machine before, go to NServiceBus.com and download it and then run the 'runmefirst.bat' from the package. It will setup Message Queueing and the DTC and some other magical things. Don't forget to unblock the file before unzipping it.
• The message queues are supposed to be created automatically, but NServiceBus might have a bad day (in terms of permissions) and fail to install them. The queues you need are (oh, and they are transactional):
  • NServiceBusSignalR.Web
  • NServiceBusSignalR.Web.Retries
  • NServiceBusSignalR.Web.Timeouts
  • NServiceBusSignalR.ConsoleApp
  • NServiceBusSignalR.ConsoleApp.Retries
  • NServiceBusSignalR.ConsoleApp.Timeouts
  • NServiceBusSignalR.Error
• You should run SignalR on an IIS or an IIS Express or a late version. Like 7.5.

Questions, Thoughts?

Contact me on twitter @MikaelOstberg