[](https://crates.io/crates/message-io)
[](https://docs.rs/message-io)
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[](https://crates.io/crates/message-io)
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# message-io
`message-io` is an event-driven message library to build network applications **easy** and **fast**.
The library handles the internal OS socket in order to offer a simple event message API to the user.
It also allows you to make an adapter for your own transport protocol following some [rules](#custom-adapter),
delegating to the library the tedious asynchrony and thread management.
<p align="center">
<img src="https://docs.google.com/drawings/d/e/2PACX-1vSPmycMsWoQq60MPEODcakFQVPkDwVy98AnduTswFNPGBB5dpbIsSCHHBhS2iEuSUtbVaYQb7zgfgjO/pub?w=653&h=305" width="653"/>
</p>
If you find a problem using the library or you have an improvement idea,
do not hesitate to open an issue. **Any contribution is welcome!**
## Motivation
Managing sockets is hard because you need to fight with threads, concurrency,
IO errors that come from the OS (which are really difficult to understand in some situations), encoding...
And if you make use of *non-blocking* sockets, it adds a new layer of complexity:
synchronize the events that come asynchronously from the OS poll.
`message-io` offers an easy way to deal with all these mentioned problems,
making them transparently for you,
the programmer that wants to make an application with its own problems.
For that, `message-io` offers a simple API and give only two concepts to understand:
**messages** (the data you send and receive), and **endpoints** (the recipients of that data).
This abstraction also offers the possibility to use the same API independently
of the transport protocol used.
You could change the transport of your application in literally one line.
## Features
- Highly scalable: **non-blocking sockets** that allows to manage thousands of active connections.
- Multiplatform: see [mio platform support](https://github.com/tokio-rs/mio#platforms).
- Multiples transports
([docs](https://docs.rs/message-io/latest/message_io/network/enum.Transport.html)):
- **TCP**: native and framed version
- **UDP**, with multicast option
- **WebSocket**: basic and secure option using
[tungstenite-rs](https://github.com/snapview/tungstenite-rs)).
- Customizable: `message-io` doesn't have the transport you need?
Add easily and [adapter](#custom-adapter).
- FIFO events with timers and priority.
- Easy, intuitive and consistent API:
- Follows [KISS principle](https://en.wikipedia.org/wiki/KISS_principle).
- Abstraction from transport layer: do not think about sockets, think about messages and endpoints.
- Only two main entities to use:
- an extensible
[`Eventqueue`](https://docs.rs/message-io/latest/message_io/events/struct.EventQueue.html)
to manage all events synchronously,
- a [`Network`](https://docs.rs/message-io/latest/message_io/network/struct.Network.html)
to manage all connections (connect, listen, remove, send, receive).
- Forget concurrence problems: handle all connection and listeners from one thread:
"One thread to rule them all".
- Easy error handling:
do not deal with dark internal `std::io::Error` when send/receive from the network.
- High performance:
- Using non-blocking sockets from one thread allows to not waste memory and time
synchonizing many threads.
- Full duplex socket: simultaneous reading/writing operations over same internal OS sockets.
## Getting started
Add to your `Cargo.toml` (all the transports included by default):
```
message-io = "0.10"
```
If you **only** want to use a subset of the available transport battery,
you can select them by their associated features `tcp`, `udp`, and `websocket`.
For example, in order to include only *TCP* and *UDP*, add to your `Cargo.toml`:
```
message-io = { version = "0.10", default-features = false, features = ["tcp", "udp"] }
```
**Warning**: If you comming from **0.9.4 o less**, note that `Transport::Tcp` has been renamed
to `Transport::FramedTcp` to be more according to its behaviour.
See more [here](https://docs.rs/message-io/latest/message_io/network/enum.Transport.html).
### Documentation
- [API documentation](https://docs.rs/message-io/)
- [Basic concepts](docs/basic_concepts.md)
- [Examples](examples):
- [Ping Pong](examples/ping-pong) (a simple client/server example)
- [Multicast](examples/multicast)
- [Distributed network with discovery server](examples/distributed)
- [File transfer](examples/file-transfer)
- Applications using `message-io`:
- [Termchat](https://github.com/lemunozm/termchat): Distributed LAN chat in the terminal.
- [AsciiArena](https://github.com/lemunozm/asciiarena): Terminal multiplayer deathmatch game
(alpha version).
### All in one: TCP, UDP and WebSocket echo server
The following example is the simplest server that reads messages from the clients and responds
to them.
It is capable to manage several client connections and listen from 3 differents protocols
at the same time.
```rust
use message_io::network::{Network, NetEvent, Transport};
fn main() {
// Create a Network with an associated event queue for reading its events.
let (mut network, mut events) = Network::split();
// Listen for TCP, UDP and WebSocket messages.
network.listen(Transport::FramedTcp, "0.0.0.0:3042").unwrap(); // Tcp encoded for packets
network.listen(Transport::Udp, "0.0.0.0:3043").unwrap();
network.listen(Transport::Ws, "0.0.0.0:3044").unwrap();
loop {
match events.receive() { // Read the next event or wait until have it.
NetEvent::Message(endpoint, data) => {
println!("Received: {}", String::from_utf8_lossy(&data));
network.send(endpoint, &data);
},
NetEvent::Connected(_endpoint) => println!("Client connected"), // Tcp or Ws
NetEvent::Disconnected(_endpoint) => println!("Client disconnected"), //Tcp or Ws
}
}
}
```
### Echo client
The following example shows a client that can connect to the previous server.
It sends a message each second to the server and listen its echo response.
Changing the `Transport::FramedTcp` to `Udp` or `Ws` will change the underlying transport used.
Also, you can create the number of connections you want at the same time, without any extra thread.
```rust
use message_io::network::{Network, NetEvent, Transport};
enum Event {
Net(NetEvent),
Tick,
// Any other app event here.
}
fn main() {
// The split_and_map() version allows to combine network events with your application events.
let (mut network, mut events) = Network::split_and_map(|net_event| Event::Net(net_event));
// You can change the transport to Udp or Ws (WebSocket).
let (server, _) = network.connect(Transport::FramedTcp, "127.0.0.1:3042").unwrap();
events.sender().send(Event::Tick); // Start sending
loop {
match events.receive() {
Event::Net(net_event) => match net_event { // event from the network
NetEvent::Message(_endpoint, data) => {
println!("Received: {}", String::from_utf8_lossy(&data));
},
_ => (),
}
Event::Tick => { // computed every second
network.send(server, "Hello server!".as_bytes());
events.sender().send_with_timer(Event::Tick, std::time::Duration::from_secs(1));
}
}
}
}
```
## Test it yourself!
Clone the repository and test the *Ping Pong* example
(similar to the *echo* example but more vitaminized).
Run the server:
```
cargo run --example ping-pong server tcp 3456
```
Run the client:
```
cargo run --example ping-pong client tcp 127.0.0.1:3456
```
You can play with it changing the transport, running several clients, disconnect them, etc.
See more [here](examples/ping-pong).
## Do you need a transport protocol that `message-io` doesn't have? Add an adapter! <span id="custom-adapter"><span>
`message-io` offers two *kinds* of APIs.
The **user API**, that talks to `message-io` itself as an user that want to use the library,
and the internal **adapter API** for those who want to add their protocol adapters into the library.
<p align="center">
<img src="https://docs.google.com/drawings/d/e/2PACX-1vRMwZsL8Tki3Sq9Zc2hpZ8L3bJPuj38zgiMKzBCXsX3wrPnfyG2hp-ijmDFUPqicEQZFeyUFxhcdJMB/pub?w=546&h=276"/>
</p>
If a transport protocol can be built in top of [`mio`](https://github.com/tokio-rs/mio)
(most of the existing protocol libraries can), then you can add it to `message-io` **really easy**:
1. Add your *adapter* file in `src/adapters/<my-transport-protocol>.rs` that implements the
traits that you find [here](https://docs.rs/message-io/latest/message_io/adapter/index.html).
It contains only 7 mandatory functions to implement (see the [template](src/adapters/template.rs)),
and take little more than 150 lines to implement an adapter file.
1. Add a new field in the `Transport` enum found in [src/transport.rs](src/transport.rs)
to register your new adapter.
That's all.
You can use your new transport with the `message-io` API like any other.
Oops! one step more, make a *Pull request* so everyone can use it :)