azure/azure-signalr

Purpose and deliverables

This is the .NET SDK for Azure SignalR Service: provider integrations for ASP.NET Core and legacy ASP.NET SignalR, a direct management SDK, shared service protocols, and a local serverless emulator. The build entry is AzureSignalR.sln; distributable package APIs are tracked under api/.

Provider entry points

ASP.NET Core applications register the Azure SignalR provider through DI and hosting/startup extensions, which replace or route SignalR lifetime and negotiate behavior through Azure SignalR. Legacy OWIN/ASP.NET SignalR has a separate integration surface.

• src/Microsoft.Azure.SignalR/DependencyInjectionExtensions.cs

• src/Microsoft.Azure.SignalR/Startup/AzureSignalRStartupFilter.cs

• src/Microsoft.Azure.SignalR.AspNet/OwinExtensions.cs

Core service-connection transport

The provider maintains outbound service connections, serializes application hub operations into service messages, and dispatches inbound messages back to local SignalR connections/hubs. Connection containers support multiple Azure endpoints and strong/weak connection modes, with acknowledgements, reconnection, shutdown, and routing boundaries.

• src/Microsoft.Azure.SignalR.Common/ServiceConnections/ServiceConnectionBase.cs

• src/Microsoft.Azure.SignalR.Common/ServiceConnections/MultiEndpointServiceConnectionContainer.cs

• src/Microsoft.Azure.SignalR/ServerConnections/ServiceConnectionManager.cs

Endpoint selection and authentication

Connection strings/configuration produce service endpoints; endpoint routers choose targets for negotiation and messages. Tokens are generated from access keys or Microsoft Entra credentials, forming the authorization boundary for service WebSocket and REST traffic.

• src/Microsoft.Azure.SignalR.Common/Endpoints/ServiceEndpoint.cs

• src/Microsoft.Azure.SignalR/EndpointRouters/DefaultEndpointRouter.cs

• src/Microsoft.Azure.SignalR.Common/Auth/MicrosoftEntra/MicrosoftEntraTokenProvider.cs

Protocol and message boundary

Microsoft.Azure.SignalR.Protocols defines the SDK-to-service message model and MessagePack-oriented service protocol. Common formatting/parsing supports binary and text frames; serverless JSON/MessagePack messages are separated into a dedicated protocol package.

• src/Microsoft.Azure.SignalR.Protocols/ServiceProtocol.cs

• src/Microsoft.Azure.SignalR.Protocols/ServiceMessage.cs

• src/Microsoft.Azure.SignalR.Serverless.Protocols/MessagePackServerlessProtocol.cs

Management SDK path

Non-hosted applications (including serverless workloads) create service hub contexts/managers to broadcast, manage clients/groups/users, negotiate clients, and perform health checks. It can use REST or WebSocket lifetime-manager transports, with resilient HTTP handlers around REST calls.

• src/Microsoft.Azure.SignalR.Management/ServiceManager.cs

• src/Microsoft.Azure.SignalR.Management/ServiceHubContextImpl.cs

• src/Microsoft.Azure.SignalR.Management/RestHubLifetimeManager.cs

Local emulator runtime

The emulator is a .NET 8 host and Docker-capable local substitute for serverless scenarios. It exposes service-like web APIs, dynamically manages hub connections/groups, proxies hub operations, and triggers configured HTTP upstreams.

• src/Microsoft.Azure.SignalR.Emulator/Program.cs

• src/Microsoft.Azure.SignalR.Emulator/Controllers/SignalRServiceEmulatorWebApi.cs

• src/Microsoft.Azure.SignalR.Emulator/HubEmulator/HubProxyHandler.cs

Runtime and external boundaries

The libraries target .NET Standard plus modern .NET variants; legacy ASP.NET support targets .NET Framework 4.6.2. Primary external systems are Azure SignalR Service (persistent WebSocket service connections and REST management APIs), Microsoft Entra authentication, ASP.NET Core SignalR/ASP.NET SignalR hosting, and optional HTTP upstream endpoints. CI is cross-platform GitHub Actions, with Azure release automation.

• src/Microsoft.Azure.SignalR/Microsoft.Azure.SignalR.csproj

• src/Microsoft.Azure.SignalR.Emulator/Dockerfile

• .azure/pipelines/release.yml