Use "Protocol Buffers" serialization from your .NET code

Introduction

protocol buffers is the name of the binary serialization format used by Google for much of their data communications. It is designed to be:

small in size - efficient data storage (far smaller than xml)
cheap to process - both at the client and server
platform independent - portable between different programming architectures
extensible - to add new data to old messages

protobuf-net is a .NET implementation of this, allowing you to serialize your .NET objects efficiently and easily. It is compatible with most of the .NET family, including .NET 2.0/3.0/3.5, .NET CF 2.0/3.5, Mono 2.x, Silverlight 2, etc.

The short version

(see also the old home page)

Serialization is a pain. protobuf-net is designed to be easily used on your existing code with minimal changes (of from an optional .proto schema), enabling fast and portable binary serialization on a wide range of .NET platforms.

Rather than being "a protocol buffers implementation that happens to be on .NET", it is a ".NET serializer that happens to use protocol buffers" - the emphasis is on being familiar to .NET users (for example, working on mutable, code-first classes if you want). I've also added a range of commonly requested features beyond the regular protobuf design, to help meet the every-day demands of .NET programmers (inheritance, reference-tracking, etc).

Usage is very simple; at the most basic level, simply read from a stream or write to a stream; see Getting Started:

// write to a file
Serializer.Serialize(outputStream, person);

...

// read from a file
var person = Serializer.Deserialize<Person>(inputStream);

Oh, and it is very fast; both in CPU and in bandwidth.

There is some VS tooling if you want to work from .proto files in visual studio, but you don't need that - you can just write a class, tell the serializer how to work with it (most commonly by adding a few attributes, but that is up to you), and serialize away.

"v2" beta released

"v2" is a major overhaul to the core engine see my blog for full details. It is wire-compatible with your existing data - simply, the library is much cleaner and leaner, and is much more versatile for onwards development. The blog (above) also describes the current state of "v2".

Author

The .proto serialization format is a credit to Google's ingenuity.

This specific .NET implementation is designed and written by Marc Gravell, developer for Stack Exchange / Stack Overflow.

Credit for various compatibility issues (mono/Silverlight) goes to M. David Peterson.

Visual Basic stylesheet contributed by Michael Thaler and Rüdiger Klaehn.

Initial code for the Visual Studio "Custom Tool" by Shaun Cooley.

Thanks also to Michael Giagnocavo, for numerous good ideas from real usage.