simple-state-machine
A simple state machine for Spring Boot projects
After importing into an IDE like STS can be run as Spring Boot application.
This project contains a framework and an illustration of the usage of the framework for a sample project like online order processing.
Usage
| Initial State | Pre-event | Processor | Post-event | Final State |
|---|---|---|---|---|
| DEFAULT -> | submit -> | orderProcessor() -> | orderCreated -> | PMTPENDING |
| PMTPENDING -> | pay -> | paymentProcessor() -> | paymentError -> | PMTPENDING |
| PMTPENDING -> | pay -> | paymentProcessor() -> | paymentSuccess -> | COMPLETED |
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To use this framework first create a state transitions table like above.
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Then implement the interfaces ProcessState and ProcessEvent. See OrderState and OrderEvent classes for examples
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Identify a primary key for the process. For the order process it would be orderId, for a time sheet application it would be userId-week-ending-date etc.
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Implement the StateTransitionsManager. See the OrderStateTransitionsManager class for an example.
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Implement the Processor class. See the OrderProcessor and the PaymentProcessor classes for examples.
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Create a controller class. See the OrderController for an example.
That is it.
For the order sample considered in this project, the following two APIs are created to test the state machine:
http://localhost:8080/order/cart?payment=123&orderId=123
(for quick testing in a browser both of the above are implemented as GET APIs)
When the above APIs are called the console log displays the state transitions that reflect the above table. (Note: payment=0 is used to mock payment error in this example)
Related Projects
A non-blocking version of this project is at: https://github.com/mapteb/non-blocking-state-machine
The technique used in this Java project can be easily adapted to Angular applications. Here is an Angular example.
More Info
More information about this project can be found at: https://dzone.com/articles/a-simple-state-machine-for-spring-boot-projects