Module event 

Event System for TAP Node

This module provides a comprehensive event handling and subscription system for TAP Node. The event system allows components to publish and subscribe to various events that occur within the node, enabling loose coupling between components and reactive programming patterns.

Event Types

The NodeEvent enum defines all the possible events that can be emitted by the TAP Node:

• PlainMessageReceived: When a message is received by an agent
• PlainMessageSent: When a message is sent from an agent to another
• AgentRegistered: When a new agent is registered with the node
• AgentUnregistered: When an agent is removed from the node
• DidResolved: When a DID is resolved (successfully or not)
• AgentPlainMessage: Raw message data intended for an agent

Subscription Models

The event system supports two subscription models:

1. Callback-based: Implementing the EventSubscriber trait to receive events via callbacks
2. Channel-based: Using tokio::sync::broadcast channels to receive events asynchronously

Built-in Event Handlers

The event system includes several built-in event handlers:

• EventLogger: Logs all events to a configurable destination (console, file, or custom handler)

Usage Examples

Callback-based Subscription

use std::sync::Arc;
use async_trait::async_trait;
use tap_node::event::{EventBus, EventSubscriber, NodeEvent};

// Create a custom event handler
struct LoggingEventHandler;

#[async_trait]
impl EventSubscriber for LoggingEventHandler {
    async fn handle_event(&self, event: NodeEvent) {
        match event {
            NodeEvent::PlainMessageReceived { message } => {
                println!("PlainMessage received: {:?}", message);
            },
            NodeEvent::AgentRegistered { did } => {
                println!("Agent registered: {}", did);
            },
            // Handle other event types...
            _ => {}
        }
    }
}

// Later, subscribe to events
async fn subscribe_events(event_bus: &EventBus) {
    let handler = Arc::new(LoggingEventHandler);
    event_bus.subscribe(handler).await;
}

Channel-based Subscription

use tap_node::event::{EventBus, NodeEvent};
use tokio::spawn;

async fn monitor_events(event_bus: &EventBus) {
    // Get a receiver for the events
    let mut receiver = event_bus.subscribe_channel();

    // Process events in a separate task
    spawn(async move {
        while let Ok(event) = receiver.recv().await {
            match event {
                NodeEvent::PlainMessageSent { message, from, to } => {
                    println!("PlainMessage sent from {} to {}", from, to);
                },
                // Handle other events...
                _ => {}
            }
        }
    });
}

Using the Event Logger

use std::sync::Arc;
use tap_node::{NodeConfig, TapNode};
use tap_node::event::logger::{EventLogger, EventLoggerConfig, LogDestination};

async fn example() {
    // Create a new TAP node
    let node = TapNode::new(NodeConfig::default());
     
    // Configure the event logger
    let logger_config = EventLoggerConfig {
        destination: LogDestination::File {
            path: "/var/log/tap-node/events.log".to_string(),
            max_size: Some(10 * 1024 * 1024), // 10 MB
            rotate: true,
        },
        structured: true, // Use JSON format
        log_level: log::Level::Info,
    };
     
    // Create and subscribe the event logger
    let event_logger = Arc::new(EventLogger::new(logger_config));
    node.event_bus().subscribe(event_logger).await;
}

Thread Safety

The event system is designed to be thread-safe, with all mutable state protected by appropriate synchronization primitives. The EventBus can be safely shared across threads using Arc<EventBus>.

Modules

customer_handler

Customer event handler for automatic customer data extraction

decision_expiration_handler

Decision expiration handler

decision_log_handler

Decision log handler

decision_state_handler

Decision state handler

handlers

Event handlers for updating message and transaction statuses

logger

Event Logger for TAP Node

trust_ping_handler

Trust Ping Response Event Handler

Structs

EventBus

Event bus for publishing and subscribing to node events

Enums

NodeEvent

Event types that can be emitted by the TAP Node

Traits

EventSubscriber

Event subscriber trait for receiving node events