DRP Interval Discovery

The DRP Interval Discovery system is a crucial component of the Distributed Resource Protocol (DRP) that enables peer discovery and connection maintenance between nodes sharing the same object IDs.

Overview

The interval discovery mechanism ensures that nodes with shared object IDs can:

• Discover each other on the network
• Maintain connections with peers
• Handle peer discovery and connection establishment gracefully

Architecture

The interval discovery system consists of three main components:

• DRPIntervalDiscovery: Manages the discovery process for a specific object ID
• IntervalRunner: Handles the periodic execution of discovery tasks
• NetworkNode: Handles P2P communication between nodes

Sequence Diagram

The following sequence diagram illustrates the discovery process:

sequenceDiagram
    box Node A
    participant Node_A_DRPIntervalDiscovery
    participant Node_A_NetworkNode
    end

    box Node B
    participant Node_B_NetworkNode
    participant Node_B_DRPIntervalDiscovery
    end

    Note over Node_A_DRPIntervalDiscovery: start() called

    loop Every interval
        Node_A_DRPIntervalDiscovery->>Node_A_NetworkNode: getGroupPeers(objectId)

        alt No peers found for objectId
            Note over Node_A_DRPIntervalDiscovery: Start search timer
            Node_A_DRPIntervalDiscovery->>Node_A_NetworkNode: broadcastMessage(DRP_INTERVAL_DISCOVERY_TOPIC)
            Node_A_NetworkNode-->>Node_B_NetworkNode: DRPDiscoveryRequest message

            alt Node B has matching objectId
                Note over Node_B_DRPIntervalDiscovery: handleDiscoveryRequest
                Node_B_DRPIntervalDiscovery->>Node_B_NetworkNode: getGroupPeers(objectId)
                Node_B_DRPIntervalDiscovery->>Node_B_NetworkNode: sendMessage(DRPDiscoveryResponse)
                Node_B_NetworkNode-->>Node_A_NetworkNode: DRPDiscoveryResponse
                Note over Node_A_NetworkNode: Contains peer multiaddrs
                Node_A_NetworkNode-->>Node_A_DRPIntervalDiscovery: handleDiscoveryResponse
                Node_A_DRPIntervalDiscovery->>Node_A_NetworkNode: connect(peer_multiaddrs)
            end
        else Peers found
            Note over Node_A_DRPIntervalDiscovery: Reset search timer
            Note over Node_A_DRPIntervalDiscovery: Skip discovery
        end
    end

    Note over Node_A_DRPIntervalDiscovery: stop() called
    Note over Node_A_DRPIntervalDiscovery: Clear interval timer

Configuration

The interval discovery system can be configured with the following options:

interface DRPIntervalDiscoveryOptions {
	/** Unique identifier for the object */
	readonly id: string;
	/** Network node instance used for peer communication */
	readonly networkNode: DRPNetworkNode;
	/** Interval in milliseconds between discovery attempts. Defaults to 10,000ms */
	readonly interval?: number;
	/** Logger configuration options */
	readonly logConfig?: LoggerOptions;
	/** Duration in milliseconds to search for peers before giving up. Defaults to 5 minutes */
	readonly searchDuration?: number;
}

Key Features

1. Periodic Discovery Checks

   • Default interval: 10 seconds
   • Configurable through interval option

2. Peer Discovery

   • Broadcasts discovery messages when no peers are found
   • Uses DRP_INTERVAL_DISCOVERY_TOPIC for discovery messages
   • Includes object ID for targeted peer matching

3. Connection Management

   • Automatically connects to discovered peers
   • Maintains connections with active peers
   • Handles peer multiaddress information

4. Search Duration

   • Default duration: 5 minutes
   • Configurable through searchDuration option
   • Prevents indefinite searching for unavailable peers

Usage

import { createDRPDiscovery } from "@ts-drp/interval-discovery";

// Create a new discovery instance
const discovery = createDRPDiscovery({
	id: "unique-object-id",
	networkNode: networkNode,
	interval: 10000, // 10 seconds
	searchDuration: 300000, // 5 minutes
});

// Start the discovery process
discovery.start();

// Stop the discovery process when done
discovery.stop();

Message Types

The discovery system uses two main message types:

1. DRPDiscoveryRequest

   • Broadcast to discover peers
   • Contains the object ID being searched for

2. DRPDiscoveryResponse

   • Sent in response to discovery messages
   • Contains peer multiaddresses for connection establishment
   • Includes subscriber information for all peers sharing the object ID

Error Handling

The discovery system includes:

• Logging of failed peer discoveries and connections
• Automatic retry mechanism within search duration