NATS.Net 2.8.0

NATS .NET

NATS .NET is the .NET client for NATS, a distributed messaging system. It provides pub/sub and request/reply (Core NATS), streaming and persistence (JetStream), Key-Value Store, Object Store, and Services.

Check out DOCS for guides and examples.

Additionally check out NATS by example - An evolving collection of runnable, cross-client reference examples for NATS.

Quick Start

Start a NATS server:

docker run -p 4222:4222 nats

Create a subscriber app:

dotnet new console -n Sub && cd Sub && dotnet add package NATS.Net

using NATS.Net;

await using var nc = new NatsClient();

await foreach (var msg in nc.SubscribeAsync<string>("greet"))
    Console.WriteLine($"Received: {msg.Data}");

In another terminal, create a publisher app:

dotnet new console -n Pub && cd Pub && dotnet add package NATS.Net

using NATS.Net;

await using var nc = new NatsClient();

await nc.PublishAsync("greet", "Hello, NATS!");

API at a Glance

using NATS.Net;

await using var nc = new NatsClient();

// Publish a message
await nc.PublishAsync("orders.new", new Order(Id: 1, Item: "widget"));

// Subscribe with async enumerable
await foreach (var msg in nc.SubscribeAsync<Order>("orders.>"))
    Console.WriteLine($"Received order: {msg.Data}");

// Request-reply
var order = new Order(Id: 2, Item: "gadget");
var reply = await nc.RequestAsync<Order, Confirmation>("orders.create", order);

// JetStream (persistent messaging)
var js = nc.CreateJetStreamContext();

// Key/Value Store
var kv = nc.CreateKeyValueStoreContext();

// Object Store
var obj = nc.CreateObjectStoreContext();

// Services
var svc = nc.CreateServicesContext();

What is NATS?

NATS is a high-performance, secure, distributed messaging system. It's a connective technology tailored for modern distributed systems, facilitating efficient addressing, discovery, and message exchange. It supports dynamic service and stream processing across various locations and devices, enhancing mobility, security, and independence from traditional constraints such as DNS.

Head over to NATS documentation for more information.

NATS .NET Goals

• Only support Async I/O (async/await)
• Target .NET Standard 2.0, 2.1, and the two most recent .NET LTS releases (currently .NET 6.0 & .NET 8.0)

Packages

• NATS.Net: Meta package that includes all other packages except extensions
• NATS.Client.Core: Core NATS
• NATS.Client.JetStream: JetStream
• NATS.Client.KeyValueStore: Key/Value Store
• NATS.Client.ObjectStore: Object Store
• NATS.Client.Services: Services
• NATS.Client.Simplified: simplify common use cases especially for beginners
• NATS.Client.Serializers.Json: JSON serializer for ad-hoc types
• NATS.Extensions.Microsoft.DependencyInjection: extension to configure DI container

Client and Orbit

NATS client functionality is split across two layers: the core client (NATS.Net, this repo) and Orbit, a separate set of packages with higher-level utilities.

The split exists so the core can stay small, stable, and consistent across NATS clients in every language, while Orbit can iterate quickly on opinionated abstractions without dragging the core API along for the ride.

Core client (NATS.Net)

• Direct API over Core NATS and JetStream as exposed by nats-server.
• Lightweight, unopinionated, performance-oriented.
• API surface kept in parity with other official NATS clients (Rust, Go, Java, JS, Python, C). A feature shipped here should look the same shape everywhere.
• Stable, conservative versioning. Breaking changes are rare and deliberate.

Orbit (orbit.net)

• Higher-level, opinionated abstractions built on top of the core client.
• Per-package versioning, so an experimental utility can iterate without bumping every other piece.
• Free to be language-specific: a .NET-idiomatic API does not need to match the equivalent in other languages.
• May lag, omit, or extend cross-client parity items.

What goes where?

Rule of thumb: if it is a thin mapping of something nats-server already speaks and every official client must expose it, it belongs in core. If it is a pattern, helper, or abstraction layered on top, it belongs in Orbit.

Layering

   ┌──────────────────────────────────────────────────────┐
   │  Application code                                    │
   └──────────────┬───────────────────────────┬───────────┘
                  │                           │
                  ▼                           ▼
        ┌───────────────────┐       ┌───────────────────┐
        │ Orbit packages    │  uses │ NATS.Net (core)   │
        │ (opinionated,     │──────▶│ (parity, stable,  │
        │  per-pkg semver)  │       │  protocol-level)  │
        └───────────────────┘       └─────────┬─────────┘
                                              │
                                              ▼
                                       ┌─────────────┐
                                       │ nats-server │
                                       └─────────────┘

Contributing

You are welcome to contribute to this project. Here are some steps to get you started:

Reporting Bugs and Feature Requests

You can report bugs and request features by opening an issue on GitHub.

Join the Community

You can join the community asking questions, sharing ideas, and helping others:

• Join the NATS Slack and find us on the #dotnet channel
• Join the discussion on GitHub Discussions
• Follow us on X @nats_io

Contributing Code

• Read the Contributor Guide
• Fork the repository and create a branch
• Open NATS.Net.slnx solution in Visual Studio, Rider or VS Code (or any other editor of your choice)
• Make changes and write tests
• Run tests against a locally installed NATS server in your PATH
• Note that some tests are still not reliable locally, so CI will run all tests
• For a quick check, run NATS.Client.Platform.Windows.Tests which is a subset of tests that should pass on Windows
• You can also locally run NATS.Client.CoreUnit.Tests and NATS.Client.Core2.Tests which are more stable
• Run dotnet format at root directory of project to clear warnings that can be auto-formatted
• Run dotnet build at root directory and make sure there are no errors or warnings
• Submit a pull request

Please also check out the Contributor Guide and Code of Conduct.

Attribution

This library is based on the excellent work in Cysharp/AlterNats