artillery/docs/building-blocks/primitives.md

title
Primitives

# Primitives

Artillery Core consists of various primitives. We will start with Service Discovery primitives and pave out way to Cluster primitives.

Service Discovery Primitives

For distributed operation we need to have a service discovery to find out who is operating/serving which services and service capabilities.

Our design consists of various service discovery techniques.

UDP Anycast

We have UDP anycast which allows the devices in the same network to nag each other continuously with a specific set of service requests to form a cluster initiation.

NOTE: Convergance of the UDP anycast might take longer time than the other zeroconf approaches.

#[derive(Serialize, Deserialize, Debug, Clone, Ord, PartialOrd, PartialEq)]
struct ExampleSDReply {
    ip: String,
    port: u16,
}

let epidemic_sd_config = ExampleSDReply {
    ip: "127.0.0.1".into(),
    port: 1337, // Cluster Formation Port of this instance
};

let reply = ServiceDiscoveryReply {
    serialized_data: serde_json::to_string(&epidemic_sd_config).unwrap(),
};

// Initialize receiver channels
let (tx, discoveries) = channel();

// Register seeker endpoint
sd.register_seeker(tx).unwrap();

// Sometimes you seek for nodes,
// sometimes you need to be a listener to respond them.
if let Some(_) = seeker {
   sd.seek_peers().unwrap();
} else {
   sd.set_listen_for_peers(true).unwrap();
}

for discovery in discoveries.iter() {
    let discovery: ExampleSDReply =
        serde_json::from_str(&discovery.serialized_data).unwrap();
    if discovery.port != epidemic_sd_config.port {
        debug!("Seed node address came");
        let seed_node = format!("{}:{}", discovery.ip, discovery.port);
        // We have received a discovery request.
    }
}