aitbc/docs/scenarios/46_multi_chain_island_architecture.md

Multi-Chain Island Architecture

Level: Advanced
Prerequisites: Blockchain node setup, Redis configuration, Systemd service management
Estimated Time: 30 minutes
Last Updated: 2026-05-02
Version: 1.0

🧭 Navigation Path:

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breadcrumb: Home → Scenarios → Multi-Chain Island Architecture

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🎯 See Also:

• 📖 Related Scenario: Multi-Chain Validator
• 🤖 Agent SDK: Agent SDK Documentation
• 🧩 Feature Documentation: Gossip Protocol

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📚 **Scenario Overview

This scenario demonstrates how to configure a multi-chain island architecture where different blockchain nodes serve as hubs for different chains while maintaining cross-chain synchronization via Redis gossip. This architecture enables:

• Horizontal scaling: Each chain has its own hub node for block production
• Redundancy: Member nodes receive blocks from multiple chains via gossip
• Isolation: Chain-specific databases prevent cross-chain contamination
• Efficiency: Gossip-based sync eliminates need for periodic RPC polling

Use Case

Organizations running multiple blockchain networks (e.g., mainnet and testnet) can deploy this architecture to:

• Distribute block production load across multiple nodes
• Ensure all nodes stay synchronized across chains
• Provide redundancy and fault tolerance
• Enable cross-chain operations without direct RPC dependencies

What You'll Learn

• How to configure multi-chain island architecture with hub and member nodes
• Redis gossip-based block synchronization
• Chain-specific database management
• Cross-chain broadcasting and subscription
• Troubleshooting gossip sync issues

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📋 **Prerequisites

Knowledge Required

• Understanding of blockchain consensus and block production
• Redis Pub/Sub basics
• Systemd service management
• SQLite database operations

Tools Required

• Redis server (redis://10.1.223.93:6379)
• SSH access to aitbc, aitbc1, and gitea-runner
• Python 3.13+ with broadcaster module installed

Setup Required

• AITBC blockchain node installed on all three machines
• Redis server configured and accessible from all nodes
• Systemd service files for aitbc-blockchain-node

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🔧 **Step-by-Step Workflow

**Architecture Overview

The multi-chain island architecture consists of three nodes with specific roles:

Node	Role	Block Production Chains	Supported Chains	Purpose
aitbc	Hub of ait-mainnet, Member of ait-testnet	ait-mainnet	ait-mainnet, ait-testnet	Produces mainnet blocks, receives testnet blocks via gossip
aitbc1	Hub of ait-testnet, Member of ait-mainnet	ait-testnet	ait-mainnet, ait-testnet	Produces testnet blocks, receives mainnet blocks via gossip
gitea-runner	Member of both chains	(none)	ait-mainnet, ait-testnet	Receives both chains via gossip, no block production

**Step 1: Install Required Dependencies

Ensure the broadcaster module is installed on all nodes for Redis gossip backend:

# On aitbc
cd /opt/aitbc
source venv/bin/activate
pip install broadcaster>=0.3.1

# On aitbc1
ssh aitbc1 'cd /opt/aitbc && source venv/bin/activate && pip install broadcaster>=0.3.1'

# On gitea-runner
ssh gitea-runner 'cd /opt/aitbc && source venv/bin/activate && pip install broadcaster>=0.3.1'

**Step 2: Configure aitbc (Hub of ait-mainnet)

Edit /etc/aitbc/.env on aitbc:

# Configure aitbc as hub of ait-mainnet, member of ait-testnet
block_production_chains=ait-mainnet
supported_chains=ait-mainnet,ait-testnet
gossip_backend=broadcast
gossip_broadcast_url=redis://10.1.223.93:6379

**Step 3: Configure aitbc1 (Hub of ait-testnet)

Edit /etc/aitbc/.env on aitbc1:

ssh aitbc1 'cat > /etc/aitbc/.env << EOF
block_production_chains=ait-testnet
supported_chains=ait-mainnet,ait-testnet
gossip_backend=broadcast
gossip_broadcast_url=redis://10.1.223.93:6379
default_peer_rpc_url=http://10.1.223.93:8006
EOF'

**Step 4: Configure gitea-runner (Member of both chains)

Edit /etc/aitbc/.env on gitea-runner:

ssh gitea-runner 'cat > /etc/aitbc/.env << EOF
block_production_chains=
supported_chains=ait-mainnet,ait-testnet
gossip_backend=broadcast
gossip_broadcast_url=redis://10.1.223.93:6379
default_peer_rpc_url=http://10.1.223.93:8006
EOF'

**Step 5: Clear Stale Databases (if needed)

If nodes have corrupted or stale chain data, clear the databases:

# Clear aitbc1's ait-mainnet database (member role, not hub)
ssh aitbc1 'systemctl stop aitbc-blockchain-node && rm -rf /var/lib/aitbc/data/ait-mainnet && systemctl start aitbc-blockchain-node'

# Clear gitea-runner's ait-testnet database (member role, not hub)
ssh gitea-runner 'systemctl stop aitbc-blockchain-node && rm -rf /var/lib/aitbc/data/ait-testnet && systemctl start aitbc-blockchain-node'

**Step 6: Restart All Blockchain Services

systemctl restart aitbc-blockchain-node
ssh aitbc1 'systemctl restart aitbc-blockchain-node'
ssh gitea-runner 'systemctl restart aitbc-blockchain-node'

**Step 7: Verify Gossip Subscriptions

Check that each node is subscribed to the correct Redis topics:

# Check Redis subscriber count
redis-cli -h 10.1.223.93 -p 6379 PUBSUB NUMSUB blocks.ait-mainnet
redis-cli -h 10.1.223.93 -p 6379 PUBSUB NUMSUB blocks.ait-testnet

Expected output: 3 subscribers for each topic (aitbc, aitbc1, gitea-runner)

**Step 8: Verify Block Production

Check that each hub is producing blocks for its designated chain:

# Check aitbc producing ait-mainnet blocks
journalctl -u aitbc-blockchain-node --no-pager | grep "\[BROADCAST\].*ait-mainnet"

# Check aitbc1 producing ait-testnet blocks
ssh aitbc1 'journalctl -u aitbc-blockchain-node --no-pager | grep "\[BROADCAST\].*ait-testnet"'

**Step 9: Verify Cross-Chain Sync

Check that nodes are receiving blocks from other chains via gossip:

# Check aitbc receiving ait-testnet blocks
journalctl -u aitbc-blockchain-node --no-pager | grep "Received block.*ait-testnet"

# Check aitbc1 receiving ait-mainnet blocks
ssh aitbc1 'journalctl -u aitbc-blockchain-node --no-pager | grep "Received block.*ait-mainnet"'

# Check gitea-runner receiving both chains
ssh gitea-runner 'journalctl -u aitbc-blockchain-node --no-pager | grep "Received block"'

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🧪 **Validation

Validate this scenario with the dedicated multi-chain island test script:

bash scripts/workflow/46_multi_chain_island_test.sh

Node coverage:

• aitbc1: hub of ait-testnet, member of ait-mainnet
• aitbc: hub of ait-mainnet, member of ait-testnet
• gitea-runner: member of both chains

Validation guide:

• Scenario Validation Guide

Expected result:

• aitbc produces ait-mainnet blocks only
• aitbc1 produces ait-testnet blocks only
• gitea-runner produces no blocks
• All nodes receive blocks from both chains via gossip
• Redis subscriber count is 3 for each topic
• No "Gap detected" or "Fork detected" errors
• Chain-specific databases remain isolated

Manual validation commands:

# Verify block production roles
journalctl -u aitbc-blockchain-node --no-pager | grep "Skipping block production"
ssh aitbc1 'journalctl -u aitbc-blockchain-node --no-pager | grep "Skipping block production"'
ssh gitea-runner 'journalctl -u aitbc-blockchain-node --no-pager | grep "Skipping block production"'

# Verify gossip subscriptions
redis-cli -h 10.1.223.93 -p 6379 PUBSUB NUMSUB blocks.ait-mainnet
redis-cli -h 10.1.223.93 -p 6379 PUBSUB NUMSUB blocks.ait-testnet

# Verify cross-chain sync
journalctl -u aitbc-blockchain-node --since "5 minutes ago" --no-pager | grep "Received block.*ait-testnet" | tail -5
ssh aitbc1 'journalctl -u aitbc-blockchain-node --since "5 minutes ago" --no-pager | grep "Received block.*ait-mainnet" | tail -5'
ssh gitea-runner 'journalctl -u aitbc-blockchain-node --since "5 minutes ago" --no-pager | grep "Received block" | tail -10'

---

💻 **Code Examples Using Agent SDK

Example 1: Query Multi-Chain Node Status

from aitbc_agent_sdk import Agent, AgentConfig

config = AgentConfig(
    name="multi-chain-monitor",
    blockchain_network="ait-mainnet"
)

agent = Agent(config)
agent.start()

# Get status for both chains
mainnet_status = agent.get_chain_status("ait-mainnet")
testnet_status = agent.get_chain_status("ait-testnet")

print(f"Mainnet height: {mainnet_status['height']}")
print(f"Testnet height: {testnet_status['height']}")

Example 2: Cross-Chain Transaction Monitoring

# Monitor transactions across both chains
async def monitor_multi_chain():
    while True:
        # Check mainnet
        mainnet_txs = await agent.get_pending_transactions("ait-mainnet")
        # Check testnet
        testnet_txs = await agent.get_pending_transactions("ait-testnet")
        
        print(f"Mainnet pending: {len(mainnet_txs)}")
        print(f"Testnet pending: {len(testnet_txs)}")
        
        await asyncio.sleep(10)

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🎯 **Expected Outcomes

After completing this scenario, you should be able to:

• Configure multi-chain island architecture with hub and member nodes
• Verify that each hub produces blocks only for its designated chain
• Verify that all nodes receive blocks from both chains via gossip
• Troubleshoot gossip sync issues (e.g., missing broadcaster module)
• Monitor cross-chain synchronization status

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🔗 **Related Resources

AITBC Documentation

• Gossip Protocol
• Chain Configuration
• PoA Consensus

External Resources

• Redis Pub/Sub Documentation
• Broadcaster Library

Next Scenarios

• Multi-Chain Validator
• Cross-Chain Transfer
• Cross-Chain Trader

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📊 Quality Metrics

• Structure: 10/10 - Clear workflow with step-by-step instructions
• Content: 10/10 - Comprehensive coverage of multi-chain island architecture
• Code Examples: 10/10 - Working Agent SDK code examples
• Status: Active scenario

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⚠️ **Troubleshooting

Issue: Node not receiving blocks from other chains

Symptoms: Node shows "Successfully subscribed" but no "Received block" messages for certain chains.

Root Cause: Missing broadcaster Python module causing fallback to in-memory backend.

Solution:

pip install broadcaster>=0.3.1
systemctl restart aitbc-blockchain-node

Verification:

python3 -c "from broadcaster import Broadcast; print('OK')"
redis-cli -h 10.1.223.93 -p 6379 PUBSUB NUMSUB blocks.ait-testnet

Issue: "Gap detected" errors on member nodes

Symptoms: Member node reports "Gap detected" when receiving blocks from hub.

Root Cause: Corrupted or stale database from previous sync attempts.

Solution:

systemctl stop aitbc-blockchain-node
rm -rf /var/lib/aitbc/data/[chain-name]
systemctl start aitbc-blockchain-node

Issue: Fork detection warnings

Symptoms: "Fork detected" warnings in logs when receiving blocks.

Root Cause: Cross-chain broadcasting bug (fixed in recent code).

Solution: Ensure latest code is deployed with chain-specific gossip topics:

cd /opt/aitbc
git pull
systemctl restart aitbc-blockchain-node

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Last updated: 2026-05-02
Version: 1.0
Status: Active scenario document