A REST API built with ASP.NET Core (.NET 10) that processes financial transactions and returns real-time statistics over a 60-second rolling window.

The API accepts transaction records and computes aggregate statistics (count, sum, average, min, max) considering only transactions from the last 60 seconds. All data is stored in-memory — no database required.

The project follows Clean Architecture with Domain-Driven Design (DDD) and CQRS via MediatR, organized into four layers:

RollingTransactionStats/
├── Domain/            # Entities, Value Objects, Domain Exceptions
├── Application/       # Commands, Queries, Handlers, Validators, DTOs
├── Infrastructure/    # In-memory repository, IoC module
└── Api/               # Controllers, Exception Handlers (Middleware)

Patterns in use:

• CQRS (Commands: create/delete; Queries: statistics)
• Value Objects (Amount, Timestamp, TransactionId) with invariant enforcement
• Repository Pattern (ITransactionRepository)
• MediatR Pipeline Behaviors (validation runs before every command handler)
• Three-tier Exception Handling (see Error Responses)

{
  "amount": 12.50,
  "timestamp": "2026-04-03T15:30:00Z"
}

Validation rules:

• amount must be >= 0
• timestamp cannot be in the future

Deletes all transactions from memory. Returns no body.

Returns aggregated statistics for all transactions within the last 60 seconds:

{
  "count": 3,
  "sum": 35.00,
  "avg": 11.67,
  "min": 5.00,
  "max": 18.50
}

If no transactions exist within the window, all values return 0.

All errors follow the RFC 7807 Problem Details format.

• .NET 10 SDK

git clone https://github.com/ramon-bernardo/RollingTransactionStats.git
cd RollingTransactionStats

dotnet run

The API will be available at:

• http://localhost:5182
• https://localhost:7251

Navigate to http://localhost:5182/swagger to explore and test the API interactively.

A ready-to-use collection is available at Postman/Collection.json. Import it into Postman to test all endpoints.

dotnet test Tests/RollingTransactionStats.Tests.csproj

Test coverage includes:

• Domain — Value Object invariants (Amount, Timestamp, Transaction)
• Application — Command handlers, query handler (rolling window logic), validators

Benchmarks are implemented with BenchmarkDotNet and cover the two main hot paths:

Each benchmark runs with TransactionCount of 10, 100, and 1_000 to observe scaling behavior.

Must be run in Release mode — BenchmarkDotNet requires it.

dotnet run --project Benchmarks/RollingTransactionStats.Benchmarks.csproj -c Release

Results are saved to Benchmarks/BenchmarkDotNet.Artifacts/ after each run.

This project is licensed under the MIT License — see the LICENSE file for details.