Temporal Money Transfer Ruby Project Template

The code in this repository demonstrates how to use the fundamental building blocks, Workflows and Activities, with the Temporal Ruby SDK. It simulates a money transfer between two bank accounts, illustrating how to implement business logic for both success and failure scenarios. This repository also serves as a template for creating new projects that use the Temporal Ruby SDK.

Although you can run the example by executing the commands shown below, our Run your first app tutorial provides more thorough coverage for this example.

Note: Code in this project uses Snipsync comment markers so that we can automatically pull certain code snippets into the tutorial.

Step 1: Setup

Use the temporal CLI to start a local Temporal Service:

temporal server start-dev

In a new terminal, clone the repository and change into the directory containing the source code:

git clone https://github.com/temporalio/money-transfer-project-template-ruby
cd money-transfer-project-template-ruby

Install the libraries needed to run the example, which includes the Temporal Ruby SDK:

bundle install

Step 2: Run the Worker

The Worker is responsible for polling the Temporal Service for incoming requests, executing the Workflow and Activity code in response to those requests, and reporting the results back to the Temporal Service.

Since the progress of a Workflow Execution depends on having at least one Worker running, start a Worker by executing the following command:

bundle exec ruby worker.rb

Step 3: Start the Workflow

In a new terminal, run the following command to start the money transfer Workflow:

bundle exec ruby starter.rb

This program submits a request to the Temporal Service, asking it to execute the Workflow with input data specified in the program.

Manually specifying input data

You can override each of those four parameters (source account, target account, amount, and reference ID) using positional commandline parameters. For example:

bundle exec ruby starter.rb A123 B789 100 REF999

Special Cases

In most cases, the Workflow Execution should succeed and you'll see a confirmation message in the terminal window. You can also examine the details in the Temporal Web UI (which should be available at this URL: http://localhost:8233).

There are two things that will trigger a different outcome:

1. If the transfer amount exceeds $1000, the withdrawal will fail due to insufficient funds. As per the custom Retry Policy in workflow.rb, this is defined as non-retryable. Since the Workflow does not provide special handling in this case, the Workflow Execution immediately fails.
2. If the target account is B5555, the deposit Activity will raise an InvalidAccountError. The Workflow provides special handling for this case by refunding the amount withdrawn back to the source account.

Testing

The test directory contains automated tests for both the Workflow and each Activity. You can execute these by running the following command from the project root.

bundle exec rake test