Nevo Messaging

A microservices messaging framework for NestJS 11+ with multi-transport support (NATS, Kafka, HTTP/SSE, HTTP/2, WebSocket, Socket.IO), designed for building scalable distributed systems with type-safe inter-service communication.

Full documentation lives in docs/. This README only covers a minimal NATS setup. For every other feature — Kafka, HTTP/2, the saga orchestrator, outbox, sliding-window circuit breakers, idempotency, JWT, OpenTelemetry, the DevTools dashboard, and a hundred more — start at the docs index.

Highlights

• 🚀 Type-safe messaging across NATS, Kafka, HTTP/SSE, HTTP/2, WebSocket, Socket.IO
• 🔄 Query (request/response), emit (fire-and-forget), publish/subscribe, broadcast, streaming
• 🎯 Declarative routing via @Signal decorator with method versioning
• 🧱 Pluggable codecs — MessagePack default, JSON, fast-json-stringify
• 🪶 Compression (gzip, deflate, zstd) with worker-thread offload
• 🧯 Resilience: retry with jitter, sliding-window circuit breaker, hedging, adaptive concurrency, idempotency cache (LRU + Redis distributed store), replay protection, rate limiting (in-process and Redis-cluster) — usable as @Hedge/@CircuitBreaker/@Adaptive/@Backpressure decorators
• 🧰 Reliable patterns: transactional outbox, effectively-once inbox (with a transactional store — e.g. PgInboxStore), saga with compensation, CQRS bridge, event store — in-memory + SQLite + Postgres production stores
• 🧪 In-memory transport (createMemoryTransport()) + MemoryHarness for unit tests with no broker dependency
• 📈 Observability: pino, Prometheus metrics, OpenTelemetry, structured DLQ
• 🪟 DevTools UI — live Next.js 16 dashboard with circuits/methods/errors/trace/replay
• 🔐 Security: ACL, JWT/JWKS, mTLS, PII redaction
• 🩺 Liveness + readiness probes with pluggable checks (pg/redis/nats/kafka/http)
• 🌐 Service discovery — built-in heartbeat + pluggable Consul / Kubernetes DNS providers
• 🛡️ Graceful shutdown, BigInt support, did-you-mean suggestions

See CHANGELOG.md for version history.

Requirements

• Node.js ≥ 24 (tested on 26) — enforced by the package's engines field, so older runtimes are refused at install time. The built-in node:sqlite store and several runtime APIs require Node 24.
• TypeScript ≥ 6
• NestJS ≥ 11

Install

npm install @riaskov/nevo-messaging
npm install @nestjs/common @nestjs/core @nestjs/microservices @nestjs/config @nestjs/platform-fastify rxjs reflect-metadata
npm install @nats-io/transport-node @nats-io/nats-core   # for NATS — install only the transport(s) you use

Fastest start: scaffold a service

npx nevo-gen user --transport nats --port 8086
cd user
npm install
npm run dev

See docs/service-scaffolding.md.

NATS quick start

A complete NATS-backed microservice is four small files.

1. Service

// user.service.ts
import { Injectable, Inject } from "@nestjs/common"
import { NatsClientBase, NevoNatsClient } from "@riaskov/nevo-messaging"

@Injectable()
export class UserService extends NatsClientBase {
  constructor(@Inject("NEVO_NATS_CLIENT") client: NevoNatsClient) {
    super(client)
  }

  async getById(id: bigint) {
    return { id, name: "John Doe", email: "john@example.com" }
  }

  async create(input: { name: string; email: string }) {
    return { id: 123n, ...input }
  }
}

2. Controller

// user.controller.ts
import { Controller, Inject } from "@nestjs/common"
import { NatsSignalRouter, Signal } from "@riaskov/nevo-messaging"
import { UserService } from "./user.service"

@Controller()
@NatsSignalRouter([UserService])
export class UserController {
  constructor(@Inject(UserService) private readonly users: UserService) {}

  @Signal("user.getById", "getById", (d: any) => [d.id])
  getById() {}

  @Signal("user.create", "create", (d: any) => [d])
  create() {}
}

3. Module

// user.module.ts
import { Module } from "@nestjs/common"
import { ConfigModule } from "@nestjs/config"
import { createNevoNatsClient } from "@riaskov/nevo-messaging"
import { UserController } from "./user.controller"
import { UserService } from "./user.service"

@Module({
  imports: [ConfigModule],
  controllers: [UserController],
  providers: [
    UserService,
    createNevoNatsClient(["COORDINATOR"], {
      clientIdPrefix: "user",
      servers: ["nats://127.0.0.1:4222"]
    })
  ]
})
export class UserModule {}

4. Bootstrap

// main.ts
import { createNatsMicroservice } from "@riaskov/nevo-messaging"
import { AppModule } from "./app.module"

createNatsMicroservice({
  microserviceName: "user",
  module: AppModule,
  port: 8086
})

Calling it from another service

@Injectable()
export class OrderService extends NatsClientBase {
  constructor(@Inject("NEVO_NATS_CLIENT") client: NevoNatsClient) {
    super(client)
  }

  async place(userId: bigint) {
    const user = await this.query("user", "user.getById", { id: userId })
    await this.emit("notifications", "order.created", { userId: user.id })
  }
}

Running a NATS broker

docker run --rm -p 4222:4222 nats:2 -js

JetStream is enabled with -js so subscriptions with { ack: true } work out of the box.

Communication patterns at a glance

// Request/response
const user = await this.query("user", "user.getById", { id: 123n })

// Fire-and-forget
await this.emit("notifications", "user.created", { userId: 123n })

// Publish / subscribe (durable JetStream consumer)
const sub = await this.subscribe(
  "user", "user.updated",
  { ack: true, durable: "audit" },
  async (msg, ctx) => { await project(msg); await ctx.ack() }
)

// Broadcast to every connected consumer
await this.broadcast("system.status", { ok: true })

See docs/messaging-patterns.md.

Where to go next

Topic	Doc
Other transports (Kafka, HTTP, HTTP/2, WS, Socket.IO)	docs/
DevTools live dashboard	docs/devtools.md
Reliable patterns (outbox, inbox, saga, CQRS, DLQ)	docs/outbox.md
Resilience decorators (@Hedge, @CircuitBreaker, @Adaptive, @Backpressure)	docs/resilience-decorators.md
Resilience (retry, breaker, hedging, rate limit)	docs/retry.md
Distributed idempotency (Redis store)	docs/idempotency.md
Service discovery (Consul, Kubernetes DNS, Etcd, Eureka, AWS Cloud Map, Nomad)	docs/discovery.md
Production storage matrix (Postgres, Redis, SQLite)	docs/storage-matrix.md
Testing with in-memory transport	docs/testing.md
Observability (OTel, metrics, health probes)	docs/observability.md
Security (ACL, JWT/JWKS, mTLS)	docs/security.md
Performance tuning	docs/performance.md

Full index: docs/README.md.

Examples

• examples/nats-user — NATS request/response + publish/subscribe + broadcast
• examples/user — standard Kafka microservice
• examples/socket-user — Socket.IO transport
• examples/http-user — HTTP query/emit + SSE subscribe + broadcast
• examples/resilience-decorators — @Hedge / @CircuitBreaker / @Adaptive / @Backpressure plus the Redis idempotency store and Consul / Kubernetes DNS discovery providers

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit (git commit -m "Add amazing feature")
4. Push (git push origin feature/amazing-feature)
5. Open a Pull Request

License

MIT — see LICENSE.

Support

• Issues: github.com/ARyaskov/nevo-messaging/issues
• Documentation: docs/
• Examples: examples/