Sunday, October 26, 2014

Game-development Log (10. Real-time with SignalR)


On this iteration I'm adding real-time notifications to the unit movement using the (awesome) SignalR library.

The idea for this will be simple: if a player moves a unit on his browser window all the others players will see that unit move in realtime on their browsers.

I've created an ultra-simple video demoing it. I've opened three separate browser windows: one with Chrome, Firefox and Safari. The movement of the units should be synchronised in real-time across the various browsers, regardless of the one that triggered the movement.

So, how was this setup? Easy as pie.

1. Add SignalR NuGet package
install-package Microsoft.AspNet.SignalR

2. Initialise SignalR on the Startup routine of ASP.NET MVC 5 (on previous versions it's slightly different)
public partial class Startup
    public void Configuration(IAppBuilder app)
3. Create a Hub
My hub will be ultra simple. It will simply receive a movement notification and share it with all the other SignalR clients as is.
public class UnitHub : Hub
    public void SetPosition(dynamic unitdata)

4. Create Javascript code both to send a SignalR message when the player moves a unit or when a notification of another player moving a unit has been received.
//code to receive notification from server
unitUpdated = function (unit) {
 // (...)

// Code to submit to server
5. (Optional) If you're using Azure, you should enable WebSockets on your website.
And that's it.

Please note that I haven't yet added persistence nor support for different users. Thus, everyone will be moving the same units. Anyway, I don't have that many page views on my blog for it to be a problem :)

So, what's next?
- Adding a database to persist the units position
- Adding users, each with his own units.
- Authentication with Facebook, Twitter, Google, Windows, Email