A Spring Boot microservice for managing financial transactions with support for concurrent processing, caching, and comprehensive error handling.
- Transaction Management (CRUD operations)
- Account Balance Management
- Pagination and Filtering Support
- Caching Implementation
- Comprehensive Error Handling
- Thread-safe Operations
- RESTful API with Swagger Documentation
- Java 21
- Spring Boot
- Spring Cache
- JUnit 5
- Swagger/OpenAPI
- Docker
- Kubernetes
The API documentation is available through Swagger UI when the application is running:
- Swagger UI: http://localhost:8080/swagger-ui.html
- OpenAPI Specification: http://localhost:8080/api-docs
You can use the Swagger UI to:
- Explore available endpoints
- View request/response schemas
- Test API endpoints directly from the browser
- Download the OpenAPI specification
GET /api/v1/accounts/{accountNo}/balance # Get account balance// GET /api/v1/accounts/ACC001/balance
200 OK
{
"balance": 1000.00
}# Create Transaction
POST /api/transactions
Content-Type: application/json
{
"accountNo": "ACC001",
"amount": 100.00,
"direction": "DEBIT"
}
# Update Transaction Status
PUT /api/transactions/{id}/status?status=SUCCESS
# Query Transactions with Filters
GET /api/transactions?accountNo=ACC001&direction=DEBIT&status=SUCCESS&minAmount=100&maxAmount=1000&fromDate=2024-01-01T00:00:00&toDate=2024-12-31T23:59:59&page=0&size=10
# Delete Transaction
DELETE /api/transactions/{id}| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
| accountNo | String | No | - | Account number to filter by |
| direction | Enum | No | - | DEBIT or CREDIT |
| status | Enum | No | - | Transaction status |
| minAmount | BigDecimal | No | - | Minimum transaction amount |
| maxAmount | BigDecimal | No | - | Maximum transaction amount |
| fromDate | LocalDateTime | No | - | Start date for transaction search |
| toDate | LocalDateTime | No | - | End date for transaction search |
| page | Integer | No | 0 | Page number (0-based) |
| size | Integer | No | 10 | Number of items per page |
// POST /api/transactions
201 Created
{
"transactionId": "TX123",
"accountNo": "ACC001",
"amount": 100.00,
"direction": "DEBIT",
"status": "PENDING",
"timestamp": "2024-01-20T10:30:00"
}
// GET /api/transactions
200 OK
{
"content": [
{
"transactionId": "TX123",
"accountNo": "ACC001",
"amount": 100.00,
"direction": "DEBIT",
"status": "SUCCESS",
"timestamp": "2024-01-20T10:30:00"
}
],
"totalElements": 1,
"totalPages": 1,
"currentPage": 0,
"pageSize": 10
}The API is documented using OpenAPI (Swagger) and can be accessed at:
GET /swagger-ui.html # Interactive API documentation
GET /v3/api-docs # OpenAPI specification-
Build the project:
mvn clean install
-
Run the application:
mvn spring-boot:run
The application will start on port 8080.
curl -X POST http://localhost:8080/api/transactions \
-H "Content-Type: application/json" \
-d '{
"amount": 100.50,
"accountNo": "12345678901",
"description": "Payment for services",
"direction": "OUT",
"status": "COMPLETED"
}'curl http://localhost:8080/api/transactionscurl http://localhost:8080/api/transactions/direction/OUTcurl http://localhost:8080/api/transactions/account/12345678901/balanceThe service automatically manages account balances based on transaction directions:
- IN: Amount is added to the account balance
- OUT: Amount is subtracted from the account balance
Account balances are initialized to 0 when the first transaction is made for a new account. All balance updates are atomic and thread-safe using ConcurrentHashMap.
- Transfers between accounts are handled as atomic operations
- Both debit and credit transactions are created in a single transaction
- Insufficient balance check is performed before the transfer
- Transaction consistency is maintained using Spring's @Transactional
The API uses standard HTTP status codes:
- 200: Success
- 201: Created
- 400: Bad Request (including insufficient balance)
- 404: Not Found
- 500: Internal Server Error
Validation errors and exceptions are returned with descriptive messages.