Wharf is a protocol that enables incremental uploads and downloads to keep software up-to-date. It includes:

• A diffing and patching algorithm, based on rsync
• An open file format specification for patches and signature files, based on protobuf
• A reference implementation in Go
• A command-line tool with several commands

Good specifications are easy to read, practical guidelines that make it easier for software to be interoperable. This book aims to be a good specification.

Its intended audience includes:

• People who want to understand the tenets of itch.io's software delivery system, to judge its worth / audit it.
• People who want to write their own, spec-compatible implementation of the protocol
• People who want to use itch.io's implementation of wharf, but with their own backend.

No spec is perfect, but it is the author's hope that, together with the community, a solid spec can be achieved and yield numerous highly-compatible implementations.

The latest version of this book is available at:

• https://docs.itch.ovh/wharf/master/index.html

Contributions can be made to it by submitting pull requests or issues on its GitHub repository:

• https://github.com/itchio/wharf-spec

Except when otherwise noted, this specification has been written by Amos Wenger