Harmony is a tool for synchronizing a repository of files between multiple locations in scenarios where there is not necessarily a single location that has all the files and still consistency is an issue.
Harmony is inspired by git-annex, but strives to be a lot more straight-forward/simple both in terms of implementation as in use.
As an example, consider a large collection of media files (music, videos, large binary asset files for a software development project) shared across different machines. In particular lets consider the following challenges that can occur in this scenario:
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There might not be a single machine having all the files, yet when a file is changed (eg. you correct the author name in a music files metadata), that change should be reflected on other devices. The same should hold through for renaming/moving of files.
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Machines might not be online when you make a change, that means synchronization might be delayed for long periods of time which can lead to changes to the same file happening at different places in parallel.
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Files may be large. That is, transfer of files should only happen when it is really requested and thus be independent from state synchronizatio.
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There is no single master location which is the only one where files will be renamed/restructured/changed while all others just read from it. Everyone that has some of the files should be able to work on the naming and directory structure, possibly in conflicting ways in parallel (which of course might require later conflict resolution).
Harmony is in an early stage of development. We have the first tests passing for local file synchronization, but the code is still subject to major changes and there is some work to be done before this is useful for productive use.
If you want to play around with it and possibly contribute, check it out and I'll be happy to assist, but under no circumstances use it on your files without making a backup first.
| Tool | Complete History | Handles large files well | Partial Checkouts | Feature-Richness |
|---|---|---|---|---|
| VCS (like Git) | Yes | No | No | |
| VCS LFS extensions (like Git LFS) | Yes | Yes | No | |
| Git Annex | Yes | Yes | Yes | Feature-rich / complex |
| Boar | Yes | Yes | No | ? |
| Directory Synchronizers (like Unison, Syncthing) | No | Yes | No | |
| Harmony | No | Yes | Yes | Lean / "KISS" |
Harmony was inspired by Git Annex but strives to be simpler. Git Annex is very powerful and feature rich by building on Git and providing a large variety of synchronization protocols, a daemon that keeps watch for file changes and other useful extensions. Harmony is built from scratch and follows more of a "keep it simple" / "do one thing well" approach.
Unison is a tool that allows synchronizing two repositories with some cleverness such as tracking changes and thus automatically choosing the newer version, asking the user what to do in case of conflicts. In contrast to Unison, Harmony does not yet have a GUI but only a command line interface. Unison however is geared towards point-to-point synchronization and can not provide a consistent repository view if files are scattered across multiple locations.