Crdt.Transport.Dtls

Crdt

High-performance, NativeAOT-ready Conflict-free Replicated Data Types (CRDTs) for modern .NET.

Crdt implements the full catalogue of CRDTs — counters, registers, sets, maps, flags, graphs, trees, JSON documents, and sequence/text types — in state-based, delta-state, and operation-based flavours, with compact binary and System.Text.Json source-generated serialization. It also includes advanced/esoteric variants (bounded, resettable, and handoff counters, causal-length sets, a tree with move, Fugue, and interval tree clocks).

✨ Why Crdt

• Strong eventual consistency without coordination: replicas converge after exchanging state, deltas, or operations.
• Fast: readonly struct building blocks, Span<T>/IBufferWriter<byte> serialization, BinaryPrimitives/Unsafe fast paths, no LINQ on hot paths.
• NativeAOT & trimming clean on .NET 8/9/10 — the library is annotated IsAotCompatible, and the test suite itself is verified running as a NativeAOT binary.
• Broad reach: targets netstandard2.0, netstandard2.1, net8.0, net9.0, net10.0 (polyfilled on older runtimes).

Supported target frameworks

📦 Install

dotnet add package Crdt

The optional replication/transport layer — in-memory, TCP (with optional TLS), and UDP anti-entropy gossip, in state-based, delta-state, and operation-based modes — ships as a separate package:

dotnet add package Crdt.Transport

DTLS-secured datagram gossip (built on DtlsSharp) lives in a further opt-in package:

dotnet add package Crdt.Transport.Dtls

MQTT broker gossip (built on Mqtt.Client) — for replicas that reach each other through an MQTT 3.1.1/5.0 broker rather than peer-to-peer — ships as another opt-in package:

dotnet add package Crdt.Transport.Mqtt

Peer-to-peer gossip over the nanomsg/NNG BUS scalability protocol (built on NanoMsgSharp, pure-managed, no broker) — over TCP, TLS, IPC, WebSockets, or in-process — ships as another opt-in package:

dotnet add package Crdt.Transport.NanoMsg

🧩 CRDT catalogue

The Counters, Sets, Trees, Documents, Sequences, and Causal clocks rows include several advanced / esoteric CRDTs (bounded, resettable, and handoff counters; causal-length set; tree-with-move; JSON document; Fugue; interval tree clocks). See Advanced / esoteric CRDTs for what each one is for.

🔁 Replication models

• State-based (CvRDT) — exchange and Merge full states. Robust to reordering and duplication.
• Delta-state — propagate small deltas of the same lattice; converges with a causal delta protocol.
• Operation-based (CmRDT) — propagate operations carrying their causal context; effects are idempotent / de-duplicated.

Crdt provides the data structures, merge/delta/operation logic, and serialization. Wiring replicas to a network (gossip, anti-entropy, broadcast) is left to the application.

📚 Documentation

• Getting started — install, your first counter, merging replicas.
• Data types — the full catalogue with usage examples for every CRDT.
• Replication models — state-based, delta-state, and operation-based, and when to use each.
• Serialization — the binary and JSON formats, value serializers, and hostile-input limits.
• Architecture — semilattices, dots, the causal kernel (ORSWOT), and the Hybrid Logical Clock.
• Performance & NativeAOT — AOT compliance, trimming, and benchmarking notes.
• Transports — the optional Crdt.Transport package: in-memory, TCP/UDP, DTLS-secured, MQTT broker, and nanomsg/NNG BUS gossip replication.

🛠️ Building from source

dotnet build Crdt.slnx -c Release
dotnet test  Crdt.slnx -c Release

Linting / formatting:

dotnet format Crdt.slnx --verify-no-changes
pwsh -NoProfile -File eng/check-line-length.ps1

NativeAOT test gate (publishes and runs the suite as a native binary):

dotnet publish tests/Crdt.Tests/Crdt.Tests.csproj -c Release -f net10.0 -r <rid> -p:AotTest=true

📄 License

MIT