Remote Model Loading

Litsea supports loading models from HTTP/HTTPS URLs in addition to local files.

Supported URI Schemes

Scheme	Example	Description
(none)	`./model.model`	Local file path (default)
`file://`	`file:///path/to/model`	Explicit file URI
`http://`	`http://example.com/model`	HTTP URL
`https://`	`https://example.com/model`	HTTPS URL

CLI Usage

echo "テスト" | litsea segment -l japanese https://example.com/japanese.model

Library Usage

#![allow(unused)]
fn main() {
let mut learner = AdaBoost::new(0.01, 100);

// Local file
learner.load_model_from_path(Path::new("./models/japanese.model"))?; // local, synchronous

// HTTP URL
learner.load_model("https://example.com/models/japanese.model").await?;
}

Since 0.6.0 the remote_model feature is opt-in (the library default is local loading only, keeping the dependency tree compact). The CLI enables it, so litsea segment https://... keeps working out of the box; library users need:

litsea = { version = "0.13.0", features = ["remote_model"] }

Implementation Details

HTTP client: reqwest with rustls (no OpenSSL dependency)
Custom User-Agent: Litsea/<version>
The load_model method is async because HTTP loading requires an async runtime
For the CLI, tokio provides the async runtime

Limits and Failure Handling

Connect timeout: 10 seconds; overall request timeout: 60 seconds – a stalled server can no longer block model loading indefinitely
Maximum model size: 256 MiB. A larger advertised Content-Length is rejected before the body is read, and an oversized body is rejected after
Incomplete downloads: when the server sends a Content-Length, a shorter received body is reported as an incomplete download
Non-2xx responses are reported as download errors with the HTTP status
The model parser additionally rejects truncated files (a model without its trailing bias line fails to load; see Model File Format)

WASM Considerations

The wasm32 target is CI-checked only without the remote_model feature (cargo check -p litsea --target wasm32-unknown-unknown --no-default-features):

HTTP/HTTPS loading is not currently supported on wasm32 – the HTTP client configuration uses reqwest’s ClientBuilder::connect_timeout and timeout, which reqwest’s WASM client does not provide, so the remote_model feature does not build for this target
Local file paths and the file:// scheme are not supported either – file system access is unavailable, so read_file_bytes returns an Unsupported error

Models must therefore be supplied by other means on wasm32, e.g. by calling load_model_from_reader with model bytes provided by the host environment.

Litsea Documentation