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README.md

UML State Machines in Step Functions

This repo demonstrates how to implement UML state machines using AWS Step Functions workflows. It features three Step Functions workflows demonstrating different UML state machine patterns:

BuySell - A flat, one-level state machine showing completion transitions and how to manage event triggers in Step Functions. This is the feature workflow, which is discussed in detail in the AWS blog post -URL to be provided-.

ServiceRequest - A hierarchical state machine featuring composite states, internal transitions, cancellation, transition to history. See resources/ServiceRequest.md

BackgroundChecks - A state machine featuring orthogonal states and cancellation. See resources/BackgroundChecks.md

The UML models are in the uml folder. The png files are screenshots of the state machines. The XML file has the models in XMI format, which should be operarable with any UML modeling tool that supports XMI. I used MagicDraw. The file contains MagicDraw extensions. Those might need to be removed before loading into a different tool.

Important: this application uses various AWS services and there are costs associated with these services after the Free Tier usage - please see the AWS Pricing page for details. You are responsible for any AWS costs incurred. No warranty is implied in this example.

Requirements

Deployment Instructions

  1. Create a new directory, navigate to that directory in a terminal and clone the GitHub repository:

    git clone https://github.com/aws-samples/step-functions-workflows-collection

  2. Change directory to the pattern directory:

    cd uml-statemachine

  3. From the command line, use AWS SAM to build and deploy the AWS resources for the workflow as specified in the template.yaml file:

    sam build
sam deploy --guided

  4. During the prompts:

    • Enter a stack name
    • Enter the desired AWS Region
    • Allow SAM CLI to create IAM roles with the required permissions.

    Once you have run sam deploy --guided mode once and saved arguments to a configuration file (samconfig.toml), you can use sam deploy in future to use these defaults.

  5. Note the outputs from the SAM deployment process. These contain the resource names and/or ARNs which are used for testing.

How it works

BlogBuySell implements a UML state machine that models the behavior of a buy-sell stock order. It demonstrates how a Step Functions workflow implements UML state activities, event dispatch, guards, transition activities, fail states, and completion transitions. Its design, and how it traces back to its UML model, is discussed in depth in the blog post -URL to be included-.

For a description of ServiceRequest, see resources/ServiceRequest.md.

For a description of BackgroundChecks, see resources/BackgroundChecks.md.

Image

image

It implements this UML state machine

image

Testing

The AWS blog post -URL to be included- walks through how to test the BlogBuySell workflow.

To test ServiceRequest, see resources/ServiceRequest.md.

To test BackgroundChecks, see resources/BackgroundChecks.md.

Cleanup

  1. Delete the stack 
    aws cloudformation delete-stack --stack-name STACK_NAME
  2. Confirm the stack has been deleted 
    aws cloudformation list-stacks --query "StackSummaries[?contains(StackName,'STACK_NAME')].StackStatus"

References

Copyright 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.

SPDX-License-Identifier: MIT-0