IonPath is a unified communication protocol and contract language designed for modern distributed applications. It combines a compact binary message format (based on CBOR) with a strongly typed DSL for defining interfaces and data contracts.

IonPath enables seamless code generation, efficient serialization, and clear separation of protocol boundaries — supporting both C# and TypeScript out of the box.

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Caution

Currently not suitable for use in a production environment, API and language have not yet been stabilized.

🔧 What is IonPath?

IonPath consists of two parts:

1. Ion Contract Language (.ion) — A compact DSL for defining types, messages, RPC methods, and event schemas
2. IonPath Protocol — A binary, CBOR-based messaging layer for exchanging typed data across systems

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✨ Features

• Declarative contract (.ion) for defining types, services, messages
• Code generation for C# and TypeScript — usable in both backend and frontend
• Compact CBOR encoding — fast, binary, schema-based
• Streaming & RPC ready — defines request/response/event shapes
• Designed for low-latency systems — suitable for WebSocket, QUIC, or custom transports
• Strong static typing & contract lockfiles — lockfiles pin contract versions across services/CI, guarantee consistency, and prevent accidental breaking changes
• Backward-compatible evolution — strict compatibility checks; the protocol safely ignores unknown fields when a consumer uses an older contract version

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Base Types Table

ion	C#	TypeScript
void	void	void
bool	bool	boolean
i1	sbyte	number
i2	short	number
i4	int	number
i8	long	bigint
i16	Int128	bigint
u1	byte	number
u2	ushort	number
u4	uint	number
u8	ulong	bigint
u16	UInt128	bigint
f2	Half	number
f4	float	number
f8	double	number
bigint	BigInteger	bigint
guid	Guid	string as Guid
string	string	string
datetime	DateTime	Date
dateonly	DateOnly	DateOnly
timeonly	TimeOnly	TimeOnly
duration	TimeSpan	Duration
uri	Uri	string as Uri
Maybe	Maybe	Maybe
Array	T[]	T[]

📣 Project Roadmap

📜 Language	Status	🛠 Code Generation	Status	🌐 Transports & Platforms	Status
Core DSL Grammar	✅	C# \ Server	✅	HTTP Transport	✅
Services	✅	C# \ Client	✅	QUIC Transport	🔻
POCO	✅	TypeScript \ Client	✅	NATS	🔻
IonPath Protocol	✅	TypeScript \ Server	🔻	WebSocket Streaming	🔻
Unions	✅	Rust \ Client	🔻	SteamNetworking	🔻
Unary Calls	✅	Rust \ Server	🔻	Unity Platform	🔻
Streaming Calls	✅	Go \ Client	🔻	Orleans Platform	🔻
Streaming Hubs	🔻	Go \ Server	🔻
		Json Serialization	🔻
		MsgPack Serialization	🔻
		CBOR Serialization	✅

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Legend: 🚧 – in progress, ✅ – implemented, 🔻 – planned