basics

The basic concepts of Restate in Python

The examples here showcase the most basic building blocks of Restate. Durable Execution, Durable Promises, and Virtual Objects, and the Workflows abstraction built on top of them.

The individual example files contain code snippets with comments and a brief descriptions about how they work and how they can be run.

Examples

• Services & Durable Execution: Running code cleanly to the end in the presence of failures. Automatic retries and recovery of previously finished actions. The example applies creates a subscription to movie streaming services by first creating a recurring payment and then adding the subscriptions.

• Building blocks: Restate gives you a durable version of common building blocks like queues, promises, RPC, state, and timers. This example shows a reference of the API and what you can do with it.

• Virtual Objects: Stateful serverless objects to manage durable consistent state and state-manipulating logic.

• Workflows: Workflows are durable execution tasks that can be submitted and awaited. They have an identity and can be signaled and queried through durable promises. The example is a user-signup flow that takes multiple operations, including verifying the email address.

Running the examples

To set up the example, use the following sequence of commands.

1. Setup the virtual env:

   python3 -m venv venv
   source venv/bin/activate
   pip install -r requirements.txt

2. Start the app as follows:

   • Durable execution example: python -m hypercorn --config hypercorn-config.toml app/0_durable_execution.py:app
   • The building blocks example is not runnable and more like a reference of what you can do with the API
   • Virtual Objects example: python -m hypercorn --config hypercorn-config.toml app/2_virtual_objects.py:app
   • Workflows example: python -m hypercorn --config hypercorn-config.toml app/3_workflows.py:app

3. Start the Restate Server (other options here):

   restate-server

4. Register the service:

   restate deployments register http://localhost:9080 --force

   Note: the '--force' flag here is to circumvent all checks related to graceful upgrades, because it is only a playground, not a production setup.

5. Check the comments in the example for how to interact with the example.

NOTE: When you get an error of the type {"code":"not_found","message":"Service 'greeter' not found. ...}, then you forgot step (5) for that example.