Distributed ledger concept in Blockchain / Solidity - Step-by-Step Execution

Concept Flow - Distributed ledger concept

Transaction Created

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Transaction Broadcast

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Nodes Receive Transaction

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Nodes Validate Transaction

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Transaction Added to Ledger

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Ledger Updated Across Nodes

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Consensus Achieved

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End

This flow shows how a transaction is created, shared, validated, added to the ledger, and synchronized across all nodes to keep the ledger consistent.

Execution Sample

Blockchain / Solidity

transaction = {'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}
network.broadcast(transaction)
for node in network.nodes:
    if node.validate(transaction):
        node.ledger.append(transaction)
network.sync_ledgers()

This code simulates creating a transaction, broadcasting it to nodes, validating it, adding it to each node's ledger, and syncing ledgers.

Execution Table

Step	Action	Transaction State	Node Ledger State	Network State
1	Create transaction	{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}	[]	Transaction ready to broadcast
2	Broadcast transaction	{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}	[]	Transaction sent to all nodes
3	Node 1 validates	Valid	[]	Waiting to add transaction
4	Node 1 adds to ledger	Valid	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]	Partial ledger updated
5	Node 2 validates	Valid	[]	Waiting to add transaction
6	Node 2 adds to ledger	Valid	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]	Partial ledger updated
7	Sync ledgers	Valid	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]	All ledgers synchronized
8	Consensus achieved	Valid	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]	Ledger consistent across network

💡 All nodes have validated and added the transaction; ledgers are synchronized and consensus is reached.

Variable Tracker

Variable	Start	After Step 4	After Step 6	Final
transaction	None	{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}	{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}	{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}
Node 1 ledger	[]	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]
Node 2 ledger	[]	[]	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]	[{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]
Network state	Idle	Transaction sent to all nodes	Partial ledger updated	Ledger consistent across network

Key Moments - 3 Insights

Why do all nodes need to validate the transaction before adding it to their ledger?

Each node must check the transaction to ensure it is valid and not fraudulent. This prevents bad data from entering the ledger, as shown in steps 3 and 5 where nodes validate before adding.

What happens if one node's ledger is different from others after adding a transaction?

The network syncs ledgers to keep them consistent, as seen in step 7. This synchronization ensures all nodes have the same ledger state, preventing conflicts.

Why is consensus important in a distributed ledger?

Consensus means all nodes agree on the ledger's content, ensuring trust and preventing fraud. Step 8 shows consensus achieved after synchronization.

Visual Quiz - 3 Questions

Look at the execution table, what is the state of Node 1's ledger after step 4?

A Transaction not added yet

B []

C [{'sender': 'Alice', 'receiver': 'Bob', 'amount': 10}]

D Ledger empty

💡 Hint

Check the 'Node Ledger State' column at step 4 in the execution_table.

At which step does the network synchronize all ledgers?

A Step 7

B Step 5

C Step 3

D Step 2

💡 Hint

Look for the action 'Sync ledgers' in the execution_table.

If Node 2 did not validate the transaction, what would happen to its ledger after step 6?

A It would include the transaction anyway

B It would remain empty

C It would crash

D It would sync automatically

💡 Hint

Refer to the 'Node Ledger State' and validation steps in the execution_table and variable_tracker.

Concept Snapshot

Distributed Ledger Concept:
- Transactions are created and broadcast to all nodes.
- Each node validates transactions independently.
- Valid transactions are added to each node's ledger.
- Ledgers are synchronized to keep data consistent.
- Consensus ensures all nodes agree on the ledger state.

Full Transcript

This visual execution shows how a distributed ledger works in a blockchain network. First, a transaction is created by a user. Then, it is broadcast to all nodes in the network. Each node receives the transaction and validates it to check if it is correct and not fraudulent. If valid, the node adds the transaction to its own ledger. After all nodes add the transaction, the network synchronizes the ledgers to make sure they all have the same data. Finally, consensus is reached when all nodes agree on the ledger's content, ensuring trust and consistency across the network.