Crates.io | tower |
lib.rs | tower |
version | 0.4.13 |
source | src |
created_at | 2016-12-23 17:20:31.319203 |
updated_at | 2022-06-17 19:45:12.713535 |
description | Tower is a library of modular and reusable components for building robust clients and servers. |
homepage | https://github.com/tower-rs/tower |
repository | https://github.com/tower-rs/tower |
max_upload_size | |
id | 7751 |
size | 480,719 |
Tower is a library of modular and reusable components for building robust networking clients and servers.
Tower aims to make it as easy as possible to build robust networking clients and servers. It is protocol agnostic, but is designed around a request / response pattern. If your protocol is entirely stream based, Tower may not be a good fit.
Tower provides a simple core abstraction, the Service
trait, which
represents an asynchronous function taking a request and returning either a
response or an error. This abstraction can be used to model both clients and
servers.
Generic components, like timeouts, rate limiting, and load balancing,
can be modeled as Service
s that wrap some inner service and apply
additional behavior before or after the inner service is called. This allows
implementing these components in a protocol-agnostic, composable way. Typically,
such services are referred to as middleware.
An additional abstraction, the Layer
trait, is used to compose
middleware with Service
s. If a Service
can be thought of as an
asynchronous function from a request type to a response type, a Layer
is
a function taking a Service
of one type and returning a Service
of a
different type. The ServiceBuilder
type is used to add middleware to a
service by composing it with multiple multiple Layer
s.
Tower is made up of the following crates:
tower
(this crate)tower-service
tower-layer
tower-test
Since the Service
and Layer
traits are important integration points
for all libraries using Tower, they are kept as stable as possible, and
breaking changes are made rarely. Therefore, they are defined in separate
crates, tower-service
and tower-layer
. This crate contains
re-exports of those core traits, implementations of commonly-used
middleware, and utilities for working with Service
s and Layer
s.
Finally, the tower-test
crate provides tools for testing programs using
Tower.
Tower provides an abstraction layer, and generic implementations of various
middleware. This means that the tower
crate on its own does not provide
a working implementation of a network client or server. Instead, Tower's
Service
trait provides an integration point between
application code, libraries providing middleware implementations, and
libraries that implement servers and/or clients for various network
protocols.
Depending on your particular use case, you might use Tower in several ways:
Implementing application logic for a networked program. You might
use the Service
trait to model your application's behavior, and use
the middleware provided by this crate and by other libraries
to add functionality to clients and servers provided by one or more
protocol implementations.
Implementing middleware to add custom behavior to network clients and servers in a reusable manner. This might be general-purpose middleware (and if it is, please consider releasing your middleware as a library for other Tower users!) or application-specific behavior that needs to be shared between multiple clients or servers.
Implementing a network protocol. Libraries that implement network
protocols (such as HTTP) can depend on tower-service
to use the
Service
trait as an integration point between the protocol and user
code. For example, a client for some protocol might implement Service
,
allowing users to add arbitrary Tower middleware to those clients.
Similarly, a server might be created from a user-provided Service
.
Additionally, when a network protocol requires functionality already provided by existing Tower middleware, a protocol implementation might use Tower middleware internally, as well as as an integration point.
A number of third-party libraries support Tower and the Service
trait.
The following is an incomplete list of such libraries:
hyper
: A fast and correct low-level HTTP implementation.tonic
: A gRPC-over-HTTP/2 implementation built on top of
hyper
. See here for examples of using tonic
with
Tower.warp
: A lightweight, composable web framework. See
here for details on using warp
with Tower.tower-lsp
and its fork, lspower
: implementations of the Language
Server Protocol based on Tower.kube
: Kubernetes client and futures controller runtime. kube::Client
makes use of the Tower ecosystem: tower
, tower-http
, and
tower-test
. See here and
here for examples of using kube
with Tower.If you're the maintainer of a crate that supports Tower, we'd love to add your crate to this list! Please open a PR adding a brief description of your library!
The various middleware implementations provided by this crate are feature flagged, so that users can only compile the parts of Tower they need. By default, all the optional middleware are disabled.
To get started using all of Tower's optional middleware, add this to your
Cargo.toml
:
tower = { version = "0.4", features = ["full"] }
Alternatively, you can only enable some features. For example, to enable
only the retry
and timeout
middleware, write:
tower = { version = "0.4", features = ["retry", "timeout"] }
See here for a complete list of all middleware provided by Tower.
Tower will keep a rolling MSRV (minimum supported Rust version) policy of at least 6 months. When increasing the MSRV, the new Rust version must have been released at least six months ago. The current MSRV is 1.49.0.
This project is licensed under the MIT license.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tower by you, shall be licensed as MIT, without any additional terms or conditions.