SMPI - SQLite Message Passing Interface

• This is a Rust based project that allows using SQLite from processes that cannot embed a C FFI.

  • E.g. a JS VM that can only send and receive messages using HTTP fetch.

• It wraps SQLites FFI and exports its own FFI.

  • Instead of the 100's of functions in SQLite, it exports a few functions that allow passing JSON messages that represent SQL queries.
  • Because JSON is serializable, these messages can pass over process and network boundaries.
    • This is not true of the SQLite FFI as it uses C pointers which ties usage to a single OS process.
  • Rust is used to cross compile a single program to many architectures.
    • This allows the same behavior over many different platforms.

• Its designed to be used in React Native mobile apps.

  • RN apps have a single JS code base that interacts with two host runtimes (iOS, Android) via message passing.
  • This Rust project has no specific RN code and is general enough to be used in other projects.

See https://sqlitempi.com/ for details.

Rust workspace/packages:

Rust workspaces are used to separate layers:

• sqliteffi
  • Converts SQLites FFI into a Rust API.
• sma
  • "State Machine A"
  • Provides a more restricted API to sqliteffi.
    • E.g.
      • WAL mode is forced.
      • Ownership is used to prevent multiple conflicting transactions starting on the same DB connection handle.
      • Reads are concurrent, writes queue.
  • Its still completely synchronous - no threading, promises or runtime.
• runtime
  • Uses the sma and provides a thread based runtime.
  • Message passing is asynchronous.
    • After the message is passed to the background thread the function returns to the caller.
    • Once the message is processed by the background thread and has a reply, a callback notifies the original caller.
• smpi_iop_ffi
  • Uses runtime to wrap the API in various FFI standards.
  • Compiles binaries that export FFI for various platforms:
    • Android
    • iOS
    • Node.js
  • See smpi_iop_ffi/sh/*

Each package has tests; run cargo test from the package directory.

Contact

Contact me for any reason emadda.dev@gmail.com.

Copyright © 2019 Enzo emadda.dev@gmail.com