SignalR difference between On and Subscribe of IHubProxy

Question

What are the differences between On and Subscribe methods available in IHubProxy interface. When should one use one over the other

Answer 1

Subscribe is lower level and you should really never have to use it. On provides friendlier overloads that allow for strong typing of arguments. Here's an example:

Server

public class MyHub
{
    public void Send(string message, int age)
    {
        Clients.All.send(message, age);
    }
}

Client

Subscribe pattern

public void Main()
{
    var connection = new HubConnection("http://myserver");
    var proxy = connection.CreateHubProxy("MyHub");

    var subscription = proxy.Subscribe("send");
    subscription.Received += arguments =>
    {
        string name = null;
        int age;
        if (arguments.Count > 0)
        {
            name = arguments[0].ToObject<string>();
        }

        if (arguments.Count > 1)
        {
            age = arguments[1].ToObject<int>();
        }

        Console.WriteLine("Name {0} and age {1}", name, age);
    };
}

"On" Pattern

public void Main()
{
    var connection = new HubConnection("http://myserver");
    var proxy = connection.CreateHubProxy("MyHub");

    proxy.On<string, int>("send", (name, age) =>
    {
        Console.WriteLine("Name {0} and age {1}", name, age);
    });
}

Answer 2

I hate to necro, but this thread lead me down a bit of a dark alleyway. It is in fact possible to use Reactive Extensions (Rx) to handle the subscriptions and in many cases this is preferable as it allows composition.

A decent enough article explaining the basics. The formatting is sadly a bit botched in the code examples but you can get there. https://www.safaribooksonline.com/blog/2014/02/10/signalr-rx-framework/