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willow-js

This is a implementation of the Willow protocol written in TypeScript.

Overview

willow-js includes a Store compliant with the Willow Data model, and a WgpsMessenger which syncs data between two stores via the Willow General Purpose Sync Protocol.

This is a low-level module for people to build their own protocols on top of, like Earthstar. It is an extremely generic and modular codebase, with many parameters to configure.

Parameters

These parameters have been abstracted as various Scheme interfaces, e.g. NamespaceScheme, SubspaceScheme, FingerprintScheme. At src/test/test_schemes.ts you can find a full suite of schemes used to configure willow-js during tests. Use these to experiment with willow-js. When you want to configure these parameter schemes yourself, please see each scheme’s accompanying documentation.

Using Store requires these schemes:

  • NamespaceScheme
  • SubspaceScheme
  • PayloadScheme
  • PathScheme
  • AuthorisationScheme
  • FingerprintScheme

Using WgpsMessenger requires all prior schemes, as well as the following:

  • AccessControlScheme
  • SubspaceCapScheme
  • PaiScheme
  • AuthorisationTokenScheme

Interfaces

In addition to these parameters, it’s possible to configure willow-js to use different drivers for entry and payload storage, transports during sync, or even different data structures to write and retrieve data from.

Most of the interfaces are geared around changing the way Store works:

  • KvDriver - an interface for writing and reading data from a key value store. We’ve chosen key-value stores as the lowest common denominator for data storage, and these drivers can be used by many different client. See our KvDriverMemory, KvDriverDeno, and KvDriverIndexedDB. This is the quickest way to adding support for new runtimes to willow-js.
  • SummarisableStorage - a data structure capable of summarising ranges of stored data as a PreFingerprint via a LiftingMonoid. See Skiplist for an implementation which reads and writes data using given KvDriver.
  • Storage3d - a data structure to write and read entries from a 3d data structure. See TripleStore for our only extant implementation of this interface, which uses three differently ordered SummarisableStorage.
  • EntryDriver - An interface encompassing all of the above to be directly provided to Store.
  • PrefixIterator - provides a means to tell if one path is prefixed by another path, and store a bit of arbitrary data with it e.g. the timestamp. See RadixTree for an example.

WgpsMessenger can communicate with peers via different transports using the Transport interface. Currently we have transports for WebSockets and in-memory.

willow-js’ Most Wanted

Here is a list of features we want to implement in willow-js. We welcome all contributions.

The number of 🌶 emoji next to each item indicates a scientifically measured estimated challenge level for each of these undertakings, three peppers being the maximum.

Storage

  • 🌶 A LevelDB driver conforming to KvDriver
  • 🌶🌶 A payload driver which intelligently stores small payloads in a database, and larger payloads on the filesystem, conforming to PayloadDriver
  • 🌶🌶🌶 A Z-ordered skiplist conforming to Storage3d (CLAIMED)

Sync

WgpsMessenger is currently compliant with the WGPS. However there are a number of optional enhancements yet to be implemented:

  • 🌶 Make WgpsMessenger send payloads below maximum_payload_size during reconciliation via ReconciliationSendPayload
  • 🌶 Make the threshold at which 3d range-based reconciliation stop comparing fingerprints and just return entries user-configurable.
  • 🌶 A WebRTC Transport.
  • 🌶🌶 Make WgpsMessenger track the progress of reconciliation using the covers field of ReconciliationSendFingerprint and ReconciliationAnnounceEntries
  • 🌶🌶 Make WgpsMessenger’s resources user configurable (currently guarantees effectively infinite memory to the other peer).
  • 🌶🌶🌶 Post-reconciliation forwarding of messages using a push-lazy-push multicast tree (plumtree), DataSetMetadata, and DataSendEntry.
  • 🌶🌶🌶 Make WgpsMessenger intelligently free handles no longer in use via ControlFree

Miscellaneous

  • 🌶 NPM compatible distribution.

Dev

Deno is used the development runtime. Run deno task test to run tests.

Want to follow along with development, ask questions, or get involved yourself? Come and join us on the Earthstar Project Discord.

This project was funded through the NGI Assure Fund, a fund established by NLnet with financial support from the European Commission’s Next Generation Internet programme, under the aegis of DG Communications Networks, Content and Technology under grant agreement № 957073.