logos-protocol/README.md

logos-protocol

The Logos protocol layer: transports, token exchange, and the language-neutral lp_* C ABI (cpp/logos_protocol.h) that every Logos SDK builds on.

Extracted from logos-cpp-sdk so that non-C++ SDKs (Rust, …) consume the same transports, capability/token flow and wire behavior through one stable, versioned boundary instead of re-wrapping the C++/Qt SDK.

What lives here

• Public C ABI — cpp/logos_protocol.h: consumer surface (lp_client_*, lp_invoke[_async], lp_subscribe, tokens, lp_get_methods), provider groundwork (lp_provider_*), and the protocol version (LOGOS_PROTOCOL_VERSION_*, lp_protocol_version(), lp_protocol_abi_major()). JSON-in-strings data model; bytes cross the boundary as {"_bytes":"<base64url>"} (lossless, NUL-safe).
• Transports — plain TCP / TCP+TLS (Boost.Asio + OpenSSL + nlohmann, Qt-free), qt_local, in-memory mock, and Qt Remote Objects (qt_remote — the only Qt-bearing transport).
• Consumer core — LogosAPIClient / LogosAPIConsumer including the automatic capability_module.requestModule token-fetch flow (behind the protocol boundary: every language gets it for free).
• Provider-side plumbing — ModuleProxy (auth gate the transports publish) and the abstract LogosProviderObject interface (logos_provider_interface.h).
• Token manager, transport/registry factories, mode config (remote/local/mock), and the canonical QVariant↔JSON conversion used at the QRO boundary.

logos-cpp-sdk layers the typed C++ developer API (LogosAPI, module context, code generator, provider base classes) on top of this repo.

Versioning

This repo carries the logos-protocol semver — the single number that governs Logos load/call compatibility. Two participants (modules, hosts, SDKs in any language) interoperate iff they share the same MAJOR. MINOR is additive/back-compatible; PATCH never affects compatibility. SDKs must re-expose the version of the protocol they linked (never mint their own).

Building

# Via workspace
ws build logos-protocol

# Standalone
nix build

# Tests
nix build .#tests

Layering invariant

logos-protocol depends only on Qt / Boost / OpenSSL / nlohmann_json — it must NEVER depend on logos-cpp-sdk, logos-qt-sdk, logos-rust-sdk, liblogos or logos-lidl. Everything points inward.