Logging Feature Architecture

The logging feature has two parts: the mw::log library that applications link against and ship as part of their own binary, and the datarouter daemon that runs as its own process. Applications never talk to datarouter directly; mw::log’s remote backend writes log records into a shared-memory segment and hands control over to datarouter through a shared-memory and mw::com message-passing session; guaranteeing Freedom from interference (FFI) for the application and its logging subsystem. Rust applications reach that same remote backend too, via the score_log_bridge described below, so datarouter sees one uniform set of sessions regardless of which frontend produced them.

mw::log

The mw::log library spans across two repositories:

score_baselibs/score/mw/log provides the Cpp frontend API, console backend, static recorder composition and the score_log Rust facade that gives Rust code the same API surface, modelled on Rust’s own log crate. This allows baselibs and mw::com to log to the same backends as applications, and providing a common logging API for all components. The library is linked into applications and shipped as part of their binary.

score_logging/score/mw/log provides concrete file, remote/DLT, and slog recorders, plus the score_log_bridge that implements score_log Log trait and forwards records over FFI into those same recorders, so a Rust application ends up writing through the identical remote backend.

Both repositories own their own safety plan, phase gates, and governance. The cross-repository contract is the Recorder interface and static backend_table registration. The existing C ABI seam is not used for static composition. Runtime plugin loading remains experimental and is not a supported production capability.

Datarouter

The Datarouter is the Diagnostic log and trace (DLT) daemon. See the Datarouter component for its requirements and detailed design.

The diagram highlights the logging components and traces the remote DLT path a log message takes once it leaves an application, including a Rust application whose score_log_bridge registers as a recorder the same way the C++ remote backend does and writes into its own shared-memory segment for datarouter to read.