SignalR vs CometD: What are the differences?
What is SignalR? A new library for ASP.NET developers that makes developing real-time web functionality easy. SignalR allows bi-directional communication between server and client. Servers can now push content to connected clients instantly as it becomes available. SignalR supports Web Sockets, and falls back to other compatible techniques for older browsers. SignalR includes APIs for connection management (for instance, connect and disconnect events), grouping connections, and authorization.
What is CometD? WebSocket & HTTP, highly scalable and clustered web messaging framework. It is a web server to push data to a browser, without the browser explicitly requesting it. It is an umbrella term, encompassing multiple techniques for achieving this interaction.
SignalR and CometD can be primarily classified as "Realtime Backend / API" tools.
SignalR is an open source tool with 7.81K GitHub stars and 2.19K GitHub forks. Here's a link to SignalR's open source repository on GitHub.