Crate bui_backend [] [src]

This library, bui-backend, enables an application to serve a Browser User Interface (BUI). The browser becomes your GUI. The API is based on futures and reactively pushes state to the browser. Assets can be served from the filesystem or bundled in the executable. The server provides an "escape hatch" to allow server-client communication outside of bui-backend. The demo includes a Rust web assembly (wasm), plain Javascript frontend and an Elm frontend. Together, this lets you ship an application written in Rust as a single file with a browser-based UI.

The operating principle is that the server runs an HTTP server (based on hyper) to which the browser connects. The initial page tells the browser to open a connection to a Server Sent Events endpoint and the server can subsequently push updates to the browser. Additionally, the server listens for POST callbacks on another endpoint. All data is encoded as JSON.


  • Uses raii-change-tracker to ensure that server state changes are reactively sent to all connected frontends.
  • To keep things simple, server state is shared with all connected clients.
  • Session keys (per browser) and connection keys (per tab) are maintained and allow taking control of communication using pre-established event stream. (This is an "escape hatch" to break out of the bui-backend abstractions as required by some use cases.)
  • Demo frontends written in Rust web assembly (wasm), Javascript and Elm. (Use bui-demo with frontend_rust_wasm, frontend_js, or frontend_elm feature.)
  • Written in async style using futures-rs.
  • Uses Serde JSON.
  • Compile-time choice between bundling served files into executable (with bundle_files feature) or reading files from disk (serve_files).

Security warning

Due to its nature, the program listens and responds to client connections from the network. If you expose your program to untrusted network connections, ensure that code within any callback handlers you write is safe when handling malicious input.



Error and result types.


Helpers for writing browser user interfaces (BUIs).


Implements a web server for a Browser User Interface (BUI).