My First Take on SignalR

My First Take on SignalR

Below are some of my notes and reference on SignalR


What is SignalR?

ASP.NET SignalR is a library for ASP.NET developers that simplifies the process of adding real-time web functionality to applications. Real-time web functionality is the ability to have server code push content to connected clients instantly as it becomes available, rather than having the server wait for a client to request new data.

SignalR provides a simple API for creating server-to-client remote procedure calls (RPC) that call JavaScript functions in client browsers (and other client platforms) from server-side .NET code. SignalR also includes API for connection management (for instance, connect and disconnect events), and grouping connections.


How does SignalR work?

Uses the following technology in the following order. You can also specify which technology to use.

  • WebSockets – real-time application
  • Event Source – real-time application
  • Forever Framing – real-time application
  • Long Polling – simulate real-time application

SignalR Security Concepts

Authentication and authorization

SignalR does not provide any features for authenticating users. Instead, you integrate the SignalR features into the existing authentication structure for an application. You authenticate users as you would normally in your application, and work with the results of the authentication in your SignalR code. For example, you might authenticate your users with ASP.NET forms authentication, and then in your hub, enforce which users or roles are authorized to call a method. In your hub, you can also pass authentication information, such as user name or whether a user belongs to a role, to the client.

SignalR provides the Authorize attribute to specify which users have access to a hub or method. You apply the Authorize attribute to either a hub or particular methods in a hub. Without the Authorize attribute, all public methods on the hub are available to a client that is connected to the hub. For more information about hubs, see Authentication and Authorization for SignalR Hubs.

You apply the Authorize attribute to hubs, but not persistent connections. To enforce authorization rules when using a PersistentConnection you must override the AuthorizeRequest method. For more information about persistent connections, see Authentication and Authorization for SignalR Persistent Connections.

Connection token

SignalR mitigates the risk of executing malicious commands by validating the identity of the sender. For each request, the client and server pass a connection token which contains the connection id and username for authenticated users. The connection id uniquely identifies each connected client. The server randomly generates the connection id when a new connection is created, and persists that id for the duration of the connection. The authentication mechanism for the web application provides the username. SignalR uses encryption and a digital signature to protect the connection token.


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