EasyNetQ.AspNetCore.SignalR 9.0.0-alpha.1

EasyNetQ.AspNetCore.SignalR

A SignalR scale-out backplane on EasyNetQ: run several servers behind a load balancer and every hub send reaches every connected client, whichever server it is on. Same semantics as Microsoft.AspNetCore.SignalR.StackExchangeRedis, over RabbitMQ (or any EasyNetQ transport) instead of Redis. Native AOT and trim safe.

using EasyNetQ;

builder.Services.AddEasyNetQ("host=rabbitmq;username=app;password=...");
builder.Services.AddSignalR()
    .AddEasyNetQ(backplane => backplane.Prefix("chat"));

AddEasyNetQ (the backplane) needs an EasyNetQ transport registered first: AddEasyNetQ(connectionString) for RabbitMQ, or AddSingleton<ITransport>(new InMemoryTransport(broker)) plus AddEasyNetQCore() in tests.

What is supported

Everything HubLifetimeManager covers, across servers:

Topology

Per hub, {prefix}.{hub full name}:

• one direct exchange: group, user and connection names are user data and never act as topic wildcards;
• one durable queue per server, {prefix}.{hub}.{server}, with x-expires (QueueExpiry, default 1 minute): it survives connection blips and broker restarts with the messages sent meanwhile, and the broker removes it once its server is gone. (RabbitMQ 4 refuses transient non-exclusive queues.) A server deletes its queue on shutdown;
• bindings all, groups, ack.{server}, return.{server}, plus conn.*/user.*/group.* while needed. Names over 255 bytes are replaced by their SHA-256.

Resilience

When the backplane's consumer connection recovers, or the broker cancels its consumer (queue deleted, queue node lost, policy change), the backplane redeclares its queue and every binding and restarts consuming. It hooks into the EasyNetQ lifecycle pipeline (LifecycleEvent.Recovered, LifecycleEvent.Cancelled); nothing to configure.

Messages are best effort, as with any SignalR backplane: a send while a server's queue is gone is lost for that server.

Options

Native AOT

The backplane itself is reflection-free (binary envelope, SignalR's own per-protocol payloads). For an AOT app, give the JSON hub protocol a source-generated context, as SignalR requires anyway:

builder.Services.AddSignalR()
    .AddJsonProtocol(o => o.PayloadSerializerOptions.TypeInfoResolverChain.Insert(0, AppJson.Default))
    .AddEasyNetQ();

EasyNetQ.Examples.SignalRAot publishes with zero trim/AOT warnings and runs the cross-server checks against a broker.

Observability

Instruments on the EasyNetQ meter: easynetq.signalr.messages (by kind and direction), easynetq.signalr.connections, easynetq.signalr.ack_timeouts, easynetq.signalr.resyncs. Backplane traffic does not run through the application's publish/consume pipelines: it is SignalR's payload, not application messages.

Not supported

• Streaming from the server to a specific client on another server is not a lifetime-manager concern in SignalR and works as usual; there is nothing extra to scale out.
• Sticky sessions are still required for transports other than WebSockets, as with every SignalR backplane.