Transactional outbox pattern + Hexagonal pattern

This repository is a proof of concept (PoC) in which I implement the transactional outbox pattern with the hexagonal pattern to have the service/sender and the message relay in the same code base to avoid having different projects sharing databases. (Also this project can be used as a template)

As the diagram shows, this project is compiled in two parts:

1. outbox-http It is the binary in charge of manage the http requests related with purchases (service/sender)
2. outbox-relay It is the binary in charge of read and send the messages (message relay)

Architecture decisions

Go project layout standard

I decided to follow the Go project layout standard.

Package tree

I built the package tree following the concepts of the hexagonal architecture pattern.

.
├── cmd
├── internal
│   ├── app
│   │   ├── business (Use cases, rules, data models and ports)
│   │   ├── input    (Everything related to "drive" adapters)
│   │   └── output   (Everything related to "driven" adapters)
│   └── container (DI container)
└── pkg (Public and global code, potencially libraries)

Compile only what is required

According to the theory of hexagonal architecture, it is possible to have n adapters for different external signals (http, gRPC, command line).

So I decided to compile a binary to handle each signal.

Database schema

The database schema is described by the .sql files in the sql directory.

To build the database run the following command.

make database

Docs

See the OpenAPI specification

See the required environment variables

How to install

Purchase service (sender)

go install -tags http github.com/yael-castro/outbox/cmd/outbox-http

Message relay

go install -tags relay github.com/yael-castro/outbox/cmd/outbox-relay

How to use from source

All compiled binaries will put in the build directory

Purchase service (sender)

make http
./build/outbox-http

Message relay

make relay
./build/outbox-relay