1# Tower Service
2
3The foundational `Service` trait that [Tower] is based on.
4
5[![Crates.io][crates-badge]][crates-url]
6[![Documentation][docs-badge]][docs-url]
7[![Documentation (master)][docs-master-badge]][docs-master-url]
8[![MIT licensed][mit-badge]][mit-url]
9[![Build Status][actions-badge]][actions-url]
10[![Discord chat][discord-badge]][discord-url]
11
12[crates-badge]: https://img.shields.io/crates/v/tower-service.svg
13[crates-url]: https://crates.io/crates/tower-service
14[docs-badge]: https://docs.rs/tower-service/badge.svg
15[docs-url]: https://docs.rs/tower-service
16[docs-master-badge]: https://img.shields.io/badge/docs-master-blue
17[docs-master-url]: https://tower-rs.github.io/tower/tower_service
18[mit-badge]: https://img.shields.io/badge/license-MIT-blue.svg
19[mit-url]: LICENSE
20[actions-badge]: https://github.com/tower-rs/tower/workflows/CI/badge.svg
21[actions-url]:https://github.com/tower-rs/tower/actions?query=workflow%3ACI
22[discord-badge]: https://img.shields.io/discord/500028886025895936?logo=discord&label=discord&logoColor=white
23[discord-url]: https://discord.gg/EeF3cQw
24
25## Overview
26
27The [`Service`] trait provides the foundation upon which [Tower] is built. It is a
28simple, but powerful trait. At its heart, `Service` is just an asynchronous
29function of request to response.
30
31```
32async fn(Request) -> Result<Response, Error>
33```
34
35Implementations of `Service` take a request, the type of which varies per
36protocol, and returns a future representing the eventual completion or failure
37of the response.
38
39Services are used to represent both clients and servers. An *instance* of
40`Service` is used through a client; a server *implements* `Service`.
41
42By using standardizing the interface, middleware can be created. Middleware
43*implement* `Service` by passing the request to another `Service`. The
44middleware may take actions such as modify the request.
45
46[`Service`]: https://docs.rs/tower-service/latest/tower_service/trait.Service.html
47[Tower]: https://crates.io/crates/tower
48## License
49
50This project is licensed under the [MIT license](LICENSE).
51
52### Contribution
53
54Unless you explicitly state otherwise, any contribution intentionally submitted
55for inclusion in Tower by you, shall be licensed as MIT, without any additional
56terms or conditions.
57