simple-state-machine

A refactored versin of this exists in the branch.

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 Workflow

Initial State	Pre-event	Processor	Post-event	Final State
DEFAULT ->	submit ->	orderProcessor() ->	orderCreated ->	PMTPENDING
PMTPENDING ->	pay ->	paymentProcessor() ->	paymentError ->	PMTPENDING
PMTPENDING ->	pay ->	paymentProcessor() ->	paymentSuccess ->	COMPLETED

To use this framework first create a state transitions table like above.
Then implement the interfaces ProcessState and ProcessEvent. See OrderState and OrderEvent classes for examples
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.
Implement the StateTransitionsManager. See the OrderStateTransitionsManager class for an example.
Implement the Processor class. See the OrderProcessor and the PaymentProcessor classes for examples.
Create a controller class. See the OrderController for an example.

Unit Testing

Unit tests can be run using the "\gradlew test" command.

Integration Testing

The application can be run using the ".\gradlew bootRun" command. For the order sample considered in this project, the following two APIs are created to test the order process:

User request to create an order. This API is implemented as GET so it can be tested quickly in the browser. http://localhost:8080/order << creates an order and returns an orderId. Selected product ids are not included in this demo example >>
User makes a payment. This API is also implemented as GET so it can be tested quickly in the browser. http://localhost:8080/order/cart?payment=123&orderId=123 << where orderId is the UUID returned by the first API. Payment value less than 1.00 is considered for the error transition >>

<< 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)

The ideas used in this project can also be adopted in Angular projects. See, for instance, https://github.com/mapteb/framework-for-angular-development

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