Vu Quy

Sharing a free, open-source library I maintain for .NET microservices.

The problem: an order DTO has a UserId, and you end up calling the user service, batching the ids and copying Name and Email back by hand, again and again.

How FxMap does it: the service that owns the data says how an entity is exposed. In the DTO you write a profile: this key fills these fields, optionally with a small expression such as Country.Name. Then one call to MapDataAsync on a list sends one request per key, not one per object. It works over gRPC, NATS, RabbitMQ, Kafka, Azure Service Bus and AWS SQS, reads from EF Core or MongoDB, and has a HotChocolate (GraphQL) integration.

Honest limits: .NET only (8, 9 and 10), gRPC calls have a fixed 3 second timeout in the current version, and the test suite is 826 tests with about 62% line coverage. Load test numbers and a benchmark are on the Testing page of the docs.

Hi everyone, I'm Quy. I write backend code in .NET, mostly microservices, and I'm new here.

I make FxMap, an open-source library that came out of a boring problem I hit again and again: an order has a UserId, and I had to call the user service, batch the ids and copy Name and Email back into the response by hand. FxMap lets you describe that once with a fluent API, and then it fetches the related fields from the service that owns them, over gRPC, NATS, RabbitMQ, Kafka and a few others.

It's a small side project that grew slowly, it is not a startup, and I'm still learning how to talk about it. I'd love to hear how other people handle data that lives in different services, and what you'd want from a tool like this.

Docs: https://fxmapper.net - Code: https://github.com/quyvu01/FxMap