Gossiper

Note: This is a work-in-progress. It's not yet usable at all!.

Gossip protocol written in Rust.

Installing Gossip

Gossip is a Cargo package. You can simply include Gossip as a dependency.

# Cargo.toml
[dependencies.gossip]
git = "https://github.com/thehydroimpulse/gossip.rs"

Getting Started

After adding Gossip as a dependency, you'll want to include the crate within your project:

extern crate gossip;

Now you'll have access to the Gossip system. We'll simply start with a brief example of creating a single server that listens on a given address. By default, this actually doesn't include any transport mechanism, so it's purely in-memory. A TCP transport is shipped with Gossip which we'll get to later on.

use gossip::{Node};

fn main() {
    // Create a new Node.
    let mut node = Node::new();

    // Bind on a specific host/port.
    node.listen("localhost", 5999).unwrap();

    // Join an existing cluster, given a peer.
    node.peer("localhost", 4555).unwrap();

    // Loop through any broadcasts that we receive.
    for (broadcast, mut res) in node.incoming() {
        // ...
        // Send an OK broadcast back, acknowledging the initial
        // broadcast.
        res.ok();
    }
}

What's A Gossip Protocol?

Wikipedia defines it as:

A gossip protocol is a style of computer-to-computer communication protocol inspired by the form of gossip seen in social networks. Modern distributed systems often use gossip protocols to solve problems that might be difficult to solve in other ways, either because the underlying network has an inconvenient structure, is extremely large, or because gossip solutions are the most efficient ones available.

The concept goes like this:

You walk into work one morning and Sam (fictional) approaches you. He tells you a secret about Billy. Excited about knowing Billy's secret, you run over to the break room to tell John. At the same time, Sam, the one who first told you, also goes and tells Jimmy. In the afternoon, all of you get together in the meeting room discussing this secret. Then, Amy, who doesn't know it yet, walks in and everybody starts telling her. At first, nobody knows if she knows the secret, so you asked, in which she replied "No?"

That's the basic workflow for gossip protocols, except, we're talking about computers and networks. This is how a network of computers can communicate without having a leader/master node. There are obvious trade-offs here. By achieving the no-leader semantics, you effectively have no control on how effective messages are getting across the network and who hasn't received them. That's the lack of consistency, yet you gain high-availability. It doesn't matter if nodes go down, there aren't any leaders, which means no quorum needs to be held, and no election processes need to happen. On top of that, any node is able to accept requests for information (i.e database queries).

For many systems and tasks, this isn't desireable. There are situations where having a consistent cluster is much simpler and more effective.

Why Rust?

Rust is Mozilla's new systems programming language that focuses on safety, concurrency and practicality. It doesn't have garbage collection — focusing on safety without sacrificing performance.

While Rust is aimed at being a systems programming language, it has powerful features allowing a high-level of abstractions. With memory safety at it's core, you can have more guarantees about software.

Papers / Research

Testing

make test

Building Gossip.rs

cargo build

License

The MIT License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

thehydroimpulse/gossiper