Flow Trading Service (FTS)

This crate is part of a collection of crates that together implement flow trading as proposed by Budish, Cramton, et al, in which trade occurs continuously over time via regularly-scheduled batch auctions.

The different crates in this workspace are as follows:

• fts_core: Defines a set of data primitives and operations but defers the implementations of these operations, consistent with a so-called "hexagonal architecture" approach to separating responsibilities.
• fts_solver: Provides a reference solver for the flow trading quadratic program.
• fts_axum: A REST API HTTP server for interacting with the solver and persisting state across auctions.
• fts_sqlite: An implementation of the core data operations using SQLite, suitable for exploration of flow trading-based marketplaces such as a forward market.

FTS SQLite

This crate provides a SQLite-based implementation of all the repository traits defined in fts-core, enabling persistent storage and retrieval of flow trading data. It's designed to be efficient for both development/testing scenarios and production use cases with moderate data volumes.

Architecture

The implementation leverages SQLite's strengths while working around its limitations:

• Dual connection pools: Separate reader and writer pools optimize for SQLite's concurrency model
• WAL mode: Write-Ahead Logging enables concurrent reads while maintaining consistency
• Temporal data model: Built-in support for historical queries and audit trails
• JSON storage: Flexible application data storage using SQLite's JSON functions