SignalR - Set ClientID Manually

Question

I want to be able to have individual users send messages to each other using SignalR, therefore I need to send to a Specific Client ID. How can I define the client ID for a specific user at the start of the session - say a GUID Primary Key for the user?

Answer 1

Replace the IConnectionIdFactory with your own https://github.com/SignalR/SignalR/wiki/Extensibility.

Sample usage: http://www.kevgriffin.com/maintaining-signalr-connectionids-across-page-instances/

EDIT: This is no longer supported in the latest versions of SignalR. But you can define a user id for a specific connection using the new IUserIdProvider

Answer 2

In SignalR version 1, using the Hubs approach, I override the Hub OnConnected() method and save an association of a .NET membership userId with the current connection id (Context.ConnectionId) in a SQL database.

Then I override the Hub OnDisconnected() method and delete the association between the .NET membership userId and the current connection id. This means, on a page reload, the userId/connectionId association will be up-to-date.

Something along the lines of:

public class MyHub : Hub
{
    private MembershipUser _user
    {
        get { return Membership.GetUser(); }
    }

    private Guid _userId
    {
        get { return (Guid) _user.ProviderUserKey; }
    }
    
    private Guid _connectionId
    {
        get { return Guid.Parse(Context.ConnectionId); }
    }

    public override Task OnConnected()
    {
        var userConnectionRepository = new UserConnectionRepository();
        userConnectionRepository.Create(_userId, _connectionId);
        userConnectionRepository.Submit();

        return base.OnConnected();
    }

    public override Task OnDisconnected()
    {
        var userConnectionRepository = new UserConnectionRepository();
        userConnectionRepository.Delete(_userId, _connectionId);
        userConnectionRepository.Submit();

        return base.OnDisconnected();
    }
}

Then when I need to trigger a SignalR event for a specific user, I can work out the connectionId from the database association(s) with the current userId - there may be more than one association if multiple browser instances are involved.