Feature Request: SignalR Protocol Binding

[bielu]

Description

I'd like to propose adding support for ASP.NET Core SignalR through a dedicated AsyncAPI binding specification.

SignalR is a widely adopted real-time communication framework in the .NET ecosystem. While SignalR commonly uses WebSockets as a transport, it introduces higher-level concepts that are not represented by existing WebSocket bindings, including:

• Hubs
• Client-to-server method invocation
• Server-to-client method invocation
• Streaming
• Groups
• User-targeted messaging
• Negotiation and transport fallback

Because of these concepts, documenting SignalR APIs using generic WebSocket bindings loses important semantic information that code generators and documentation tools could otherwise leverage.

Motivation

Many organizations use AsyncAPI to document event-driven and real-time systems. SignalR applications currently require custom extensions or incomplete WebSocket representations.

A dedicated SignalR binding could:

• Improve documentation quality
• Enable code generation for SignalR clients and servers
• Standardize SignalR API descriptions across projects
• Better represent hub-based communication patterns

Initial Ideas

A SignalR binding might include metadata such as:

• Hub name
• Target method
• Invocation type
• Streaming configuration
• Group messaging semantics
• User-targeted delivery semantics

Example:

channels:
  notifications:
    bindings:
      signalr:
        hub: NotificationsHub
        target: ReceiveNotification

Or alternatively at the operation level:

operations:
  sendMessage:
    action: send
    bindings:
      signalr:
        hub: ChatHub
        method: SendMessage

Questions

• Would SignalR fit better as a dedicated protocol binding or as an extension of the existing WebSocket binding?
• Are there existing binding design patterns that would be appropriate for hub-based communication frameworks?
• Is there community interest in collaborating on a formal proposal (AIP)?

I'd be happy to contribute a draft specification if the maintainers believe this aligns with the AsyncAPI roadmap.

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