Source code in this repository is to support a Spring Sate Machine presentation. The idea behind the project is to show how SSM can be used to implement a Distributed Saga and orchestrate a business transaction spanning multiple microservices.
The presentation can be found here: Orchestrating transactions over Microservices with Sagas and Spring Statemachine
- The project is implemented as a multi-module maven project to simplify development (in real life I would expect that each service is implemented by a separate team as a standalone project, or perhaps it is 3rd party services, and BOM to be defined on the organization/tribe level that reflects common versions of the most important dependencies. It also can be the case that BOM is not used at all).
- DTOs are implemented separately in each service. In real life it may be implemented as a schema registry (if there is a centralized API management), or by each team independently.
- DTOs are oversimplified. They do not represent real business objects and are needed just to represent the data flows.
The workflow is set up in the following way:
- book a flight, if it is successful:
- book a hotel, if it is successful:
- book a car, if it is successful:
- if it is successful, return the overall result,
- if there is an error on any of the stage, try cancelling previous bookings and return 'not found'.
Value of parameters and overall result:
| flightCode | hotelName | carName | Result |
|---|---|---|---|
| KL1009 | TULIP INN | Fiat | OK |
| KL0000 | TULIP INN | Fiat | NOK, cancel on a flight |
| KL1009 | Some Hotel | Fiat | NOK, cancel on a hotel after the flight is booked |
| KL1009 | TULIP INN | NOT Fiat | NOK, cancel on a car after the flight and the hotel are booked |
- Navigate to the ./docker folder and run > docker-compose up there. It will spin up ActiveMQ, Zipkin and MySQL
- Run travel-agency-eureka service
- Wait a minute before the services will spin up
- Run travel-agency-config-server
- Run travel-agency-api-gateway
- Run hotel-reservation-service
- Run flight-reservation-service
- Finally, run travel-agent-service
WIP. Please note, the following steps are in WIP phase and not available yet
- TODO: build docker images for all services in the project
- TODO: Navigate to the ./docker folder and run > docker-compose with docker-compose-all.yml up there.
- Wait a couple of minutes until the system will spin up all services
| Service name | Port | Comments |
|---|---|---|
| travel-agency-eureka | 8761 | Service Discovery |
| travel-agency-api-gateway | 9090 | API Gateway |
| travel-agency-config-server | 8888 | Externalized configuration |
| Zipkin | 9411 | Distributed tracing |
| ActiveMQ | 8161, 61616 | JMS |
| Mongo | 27017 | |
| Mongo Express | 8091 | Mongo Admin UI |
| MySQL | 3306 | RDBMS |
| Service name | Port | Comments |
|---|---|---|
| hotel-reservation-service | 8081 | Hotel Reservation Service |
| flight-reservation-service | 8082 | Flight Reservation Service |
| car-rental-service | 8083 | Car Rental Service |
| Service name | Port | Comments |
|---|---|---|
| travel-agent-service | 8080 | Orchestrator |