Tokio

Tokio is a one-stop-shop for all your async I/O needs in Rust. At the heart of Tokio is the futures crate to model asynchronous computations, and you'll find all layers from futures to event loops to protocols to services in the various Tokio crates.

Note: Currently the Tokio project is a work in progress, so breakage should be expected. Crates will be published to crates.io as they begin to stabilize, and this repository itself will eventually be home to a tokio crate as well. Stay tuned for updates!

What is Tokio?

Tokio is a an async I/O stack in Rust running the full gamut in terms of what it provides. At the very bottom you'll find the tokio-core crate with a bare-bones event loop and Future spawning. Near the top you'll find the tokio-proto crate with generic implementations of protocol details like pipelining and multiplexing used to serve requests to the Service trait in tokio-service inspired by Finagle.

The Tokio project is split into a number of crates to encapsulate responsibilities and encourage reuse. Some layers of the Tokio stack are more "opinionated" than others, for example with a particular buffering strategy. Currently the lowest layers, tokio-core and tokio-service, are intended to be zero-to-very-low cost abstractions while moving up to crates like tokio-proto may not be zero cost for some applications.

It's intended that the tokio crate (not existent yet) is generally what you'll want for async I/O, and more specialized applications can use the dependencies individually. This document is then intended to help you navigate what's available!

Tokio Crates

• tokio-core - the core I/O event loop for all of Tokio
• tokio-service - definition of the Service trait for applications wishing to define a service or work with middleware.
• tokio-proto - protocol implementation utilities such as pipelining/multiplexing
• tokio-curl - a sample HTTP client backed by libcurl
• tokio-socks5 - a sample SOCKSv5 proxy server
• tokio-line - a sample line-based protocol for using tokio-proto
• tokio-middleware - collection of middleware using the tokio-service crate
• tokio-minihttp - a mini HTTP server implementation intended to showcase tokio-proto
• tokio-redis - an implementation of the Redis protocol using tokio-proto
• tokio-timer - a timer wheel and other timer-related functions for use with an event loop
• tokio-tls - an implementation of TLS/SSL streams used by tokio-minihttp for an SSL server
• tokio-uds - Unix domain sockets for tokio-core

Third-party Tokio Crates

In addition to the crates above in the tokio-rs organization, there are a few crates outside the organization which integrate with Tokio:

• tokio-dns - asynchronous DNS resolution and utilities
• tokio-signal - Unix signal handling and Windows console control events
• tokio-process - process management and spawning

Current Status

A bottom-up approach is currently being used to stabilize pieces and enable more and more applications to build on the stable portions of Tokio. The futures crate recently published 0.1, and the Tokio crates are intended to follow suit soon. Listed below is a table of the current status of each crate.

Crate	Status
tokio-core	0.1 on crates.io
tokio-service	Nearly 0.1
tokio-proto	Waiting on tokio-core, next major piece
tokio-curl	0.1 on crates.io
tokio-timer	Waiting on final audit of APIs
tokio-tls	Waiting on native-tls
tokio-uds	0.1 on crates.io
tokio-middleware	Planned soon after tokio-service

Note that the following example projects are not currently intended to be published on crates.io:

• tokio-socks5
• tokio-line
• tokio-minihttp
• tokio-redis

License

Tokio is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.

See LICENSE-APACHE, and LICENSE-MIT for details.