Crypto API

The Crypto API provides seamless interaction with the Solana blockchain, allowing users to check balances, transfer SOL tokens, and handle airdrops in the event of insufficient funds.

Table of Contents

• Key Features
• Technologies Used
• Transfer SOL Flow
  • Components
  • System Diagram
  • Sequence Diagram
• Transfer Ethereum Flow
  • Components
  • System Diagram
  • Sequence Diagram
• Running the Application
• Testing the API
  • Get Balance
  • Transfer SOL
  • Transfer Ethereum
• Blockchain Transaction Details
• Deployed Application

Key Features

• Check Balance: Retrieve the SOL balance for any Solana wallet.
• Transfer SOL: Transfer SOL between two wallets with automatic validation and SOL airdrop for insufficient funds.
  • Both sender and receiver balances are checked.
  • If funds are insufficient, an airdrop is automatically initiated to complete the transaction.

Technologies Used

• Java 21: Leveraging the latest features for performance and scalability.
• Spring Boot 3.3.3: Simplifies building production-ready applications.
• Hexagonal Architecture: Clean separation between core logic and infrastructure for better maintainability.
• WireMock: For mocking API interactions during tests.
• SpringDoc OpenAPI: Auto-generates OpenAPI documentation for improved API interoperability.
• GitHub Actions: CI/CD pipelines for automated testing and quality analysis.
• SonarCloud: Ensures code quality and security with continuous static analysis.
• Codacy: Provides additional insights into code quality.

Transfer SOL Flow

Components

System Diagram

The diagram below illustrates the interaction between components within the hexagonal architecture for SOL transfers.

Sequence Diagram

This diagram details the sequence of operations that occur during a SOL transfer.

Transfer Ethereum Flow

Components

The Ethereum transfer system uses the following components:

• TransferController: Handles requests for Ethereum balance transfers.
• TransferService: Executes the business logic for transferring Ethereum, including balance checks and signing transactions.
• BalanceAdaptor: Fetches the Ethereum balance of the sender.
• TransferAdaptor: Sends signed Ethereum transactions to the blockchain via Web3j.

Class Diagram

This system diagram illustrates the interaction of components during an Ethereum transfer in a Hexagonal Architecture model.

Sequence Diagram

The sequence diagram below details the steps for an Ethereum transfer, including address validation, balance checks, and sending the transaction.

Running the Application

To run the Crypto API locally, use the following Gradle command:

./gradlew :app:bootRun

Testing the API

You can test the API functionality using curl commands as shown below.

1. Get Balance

To fetch the balance of a Solana wallet, use the following command:

curl --location 'http://localhost:8080/api/v1/balances/p8guAeE7naqQcT2JMCp8Q376MLyzt5XynfGw3uCHM75'

2. Transfer SOL

To transfer SOL between two wallets, use the following command:

curl --location 'http://localhost:8080/api/v1/transfers' \
--header 'Content-Type: application/json' \
--data '{
"to" : "81e58SU8EHdBmSnETExsCwurbfWeCbNg9UoAFmKPyyj3",
"amount" : "1000"
}'

This will initiate a transfer of 1000 lamports to the specified wallet address.

3.Transfer Ethereum

curl --location 'http://localhost:8080/api/v1/transfers' \
--header 'Content-Type: application/json' \
--data '{
"to" : "0x5d940f3947c4ab1fbdbf1f540a10019931065f7a",
"amount" : "0.05"
}'

Verifying the Transaction

Solana Transaction

Once the transfer has been made, capture the transaction signature from the logs.

To verify the transaction:

1. Go to Solana Explorer.
2. Paste the transaction signature into the search bar.
3. Press Enter to view the transaction details and confirm the transfer status.

Solana Transaction Details

Signature

• 5xRDwYsgDLMXpkkYLXbvmB66c4ENq9cgZue3S2Fo38FSnf6tCB8VDFNGL77gvRhADX2wzULVwcsCE59ZzyHm7TAZ
  • This is the unique transaction identifier, known as the transaction signature. It's similar to a receipt ID that you can use to look up and verify the transaction on Solana Explorer.

Result

• Success
  • Indicates that the transaction was successfully processed.

Timestamp

• Sep 13, 2024 at 14:44:20 Central European Summer Time
  • The exact date and time when the transaction was confirmed on the Solana blockchain, in the specified time zone.

Confirmation Status

• finalized
  • This means that the transaction has been permanently included in the blockchain, and all nodes have agreed upon its validity.

Confirmations

• max
  • Indicates that the transaction has the maximum number of confirmations possible, ensuring it is fully validated.

Slot

• 325,730,164
  • A slot is a period during which a validator can propose a block. This is the slot number where your transaction was included.

Recent Blockhash

• 7DDLsppuoykdpJ168HgZAztzheN9Gehn43BSMCyQBohs
  • The blockhash used for this transaction, which ensures that it was included in a specific block of the blockchain. Each transaction is tied to a recent blockhash to prevent replay attacks.

Fee (SOL)

• ◎0.000005
  • The transaction fee paid for processing the transaction on the Solana blockchain, in SOL. The symbol "◎" is commonly used to denote SOL.

Compute Units Consumed

• 150
  • This represents the amount of computational resources (in units) consumed to process the transaction. More complex transactions may consume more units.

Transaction Version

• legacy
  • Refers to the version of the Solana transaction format being used. In this case, it's the "legacy" version.

---

Account Input(s)

This section shows the Solana accounts involved in the transaction and how their balances changed.

1. p8guAeE7naqQcT2JMCp8Q376MLyzt5XynfGw3uCHM75

• Change (SOL): -◎0.000006 (This account paid the fee for the transaction)
• Post Balance (SOL): ◎1.998435
• This is the fee payer for the transaction, and also the sender of the SOL in this transaction.

2. 81e58SU8EHdBmSnETExsCwurbfWeCbNg9UoAFmKPyyj3

• Change (SOL): +◎0.000001
• Post Balance (SOL): ◎1.00078
• This is the recipient of the transferred SOL.

3. System Program

• This is the built-in Solana program used to handle basic tasks like transferring SOL between accounts.

---

Instruction

1. System Program: Transfer

• This indicates that the transaction involved the System Program for transferring SOL.

• From Address: p8guAeE7naqQcT2JMCp8Q376MLyzt5XynfGw3uCHM75 (Sender)

• To Address: 81e58SU8EHdBmSnETExsCwurbfWeCbNg9UoAFmKPyyj3 (Recipient)

• Transfer Amount (SOL): ◎0.000001

• This instruction shows that 0.000001 SOL was transferred from the sender to the recipient.

---

Program Instruction Logs

• Program returned success
  • The program responsible for handling the transaction (in this case, the System Program) returned successfully, meaning the transfer was executed without errors.

---

Summary

• The transaction successfully transferred 0.000001 SOL from the sender to the recipient.
• A transaction fee of 0.000005 SOL was charged to the sender.
• The transaction was finalized and is now a permanent part of the Solana blockchain, confirmed at slot 325,730,164.

---

Ethereum Transaction Details

After initiating an Ethereum transfer, you can verify the transaction on the Ethereum blockchain using the transaction hash.

capture the transaction signature from the logs.

To verify the transaction:

1. Go to Ether Scan.
2. Paste the transaction signature into the search bar.
3. Press Enter to view the transaction details and confirm the transfer status.

Transaction Hash:

• 0x7dbf2e5864e4db7ea72aa0dd476a35cd3b10a8e9d58b84032286f491484f2abb
  • This is the unique identifier for the transaction, which can be used to track and verify it on the Ethereum blockchain via a block explorer like Etherscan.

Status:

• Success
  • The transaction was processed successfully and is now included in the blockchain.

Block:

• 6707629
  • The transaction was included in this block on the Ethereum blockchain.
  • A block is a group of transactions that were confirmed and added to the blockchain.

Block Confirmations:

• 32103 Block Confirmations
  • The number of blocks that have been mined since the block containing this transaction. More confirmations make the transaction more secure and harder to reverse.

Timestamp:

• Sep-17-2024 06:49:00 AM UTC (5 days ago)
  • This is the exact date and time when the transaction was included in the blockchain.

---

Parties Involved

From:

• 0x4281eCF07378Ee595C564a59048801330f3084eE
  • This is the Ethereum address of the sender (the account that initiated the transaction and paid for the gas fees).

To:

• 0xbd3a24C4447E0AaCdf1000d478186E16Ba2c013A
  • This is the Ethereum address of the recipient (the account that received the funds).

---

Transaction Details

Value:

• 0.1 ETH
  • The amount of Ether (ETH) transferred from the sender to the recipient. In this case, 0.1 ETH was sent.
  • USD Equivalent: $0.00 (at the time of transaction)

Transaction Fee:

• 0.00001187750844 ETH
  • The total amount of gas fees paid by the sender to process the transaction.
  • USD Equivalent: $0.00 (at the time of transaction)

Gas Price:

• 0.56559564 Gwei (0.00000000056559564 ETH)
  • The price per unit of gas paid in Gwei. The gas price fluctuates based on network demand and determines how quickly miners will process the transaction.

Gas Limit & Usage by Transaction:

• Gas Limit: 60,000
  • The maximum amount of gas units that the sender was willing to pay for this transaction.
• Gas Used: 21,000
  • The actual amount of gas consumed by the transaction, which was 35% of the gas limit.

---

Gas Fees Breakdown

Gas Fees:

• Base Fee: 0.282877339 Gwei
  • The base fee is the minimum amount of gas required for this transaction, set by the Ethereum network.
• Max Fee: 0.56559564 Gwei
  • The maximum gas fee the sender was willing to pay.
• Max Priority Fee: 0.56559564 Gwei
  • The maximum priority fee offered by the sender to incentivize miners to prioritize this transaction.

Burnt & Transaction Savings Fees:

• 🔥 Burnt: 0.000005940424119 ETH
  • Under EIP-1559, part of the gas fee is burned (removed from circulation) to reduce Ethereum supply, making the network deflationary.
• 💸 Transaction Savings: 0 ETH
  • Any savings from unused gas.

---

Other Transaction Attributes

Transaction Type:

• 2 (EIP-1559)
  • This transaction follows the EIP-1559 standard, which introduced dynamic gas fees and the concept of gas burning.

Nonce:

• 1278598
  • The transaction nonce is a unique number associated with the sender's account. It represents the number of transactions sent from this address.

Position in Block:

• 3
  • The transaction was the 3rd transaction included in block 6707629.

---

Summary:

• 0.1 ETH was successfully transferred from 0x4281eCF07378Ee595C564a59048801330f3084eE to 0xbd3a24C4447E0AaCdf1000d478186E16Ba2c013A.
• The transaction incurred a fee of 0.00001187750844 ETH.
• The transaction used 21,000 gas out of a 60,000 gas limit.
• 0.000005940424119 ETH was burned as part of the EIP-1559 protocol.
• The transaction is securely confirmed with 32103 block confirmations.

Deployed Application

The application is deployed and accessible here.

References

• Solana Documentation
• Solana Explorer
• Solana Whitepaper
• Ether Scan
• Quicknode