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README.md

Examples of the basic concepts for Restate in TypeScript / JavaScript

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

  • Basic Durable Execution:: Running code cleanly to the end in the presence of failures. Automatic retries and recovery of previously finished actions. The example applies a series of updates and permission setting changes to user's profile.

  • Durable Execution with Compensations: Reliably compensating / undoing previous actions upon unrecoverable errors halfway through multi-step change. This is the same example as above, extended for cases where a part of the change cannot be applied (conflict) and everything has to roll back.

  • 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.

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

  • Kafka Event-processing: Processing events to update various downstream systems with durable event handlers, event-delaying, in a strict-per-key order.

  • Stateful Event-processing: Populating state from events and making is queryable via RPC handlers.

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

  2. Install the requirements:

    pip install -r requirements.txt

  3. Start the app as follows:

    • Durable execution example: python -m hypercorn --config hypercorn-config.toml app/1_durable_execution.py:app
    • Durable execution with compensations example: python -m hypercorn --config hypercorn-config.toml app/2_durable_execution_compensation.py:app
    • Workflows example: python -m hypercorn --config hypercorn-config.toml app/3_workflows.py:app
    • Virtual Objects example: python -m hypercorn --config hypercorn-config.toml app/4_virtual_objects.py:app
    • Kafka Event-processing example: python -m hypercorn --config hypercorn-config.toml app/5_events_processing.py:app
    • Stateful Event-processing example: python -m hypercorn --config hypercorn-config.toml app/6_events_state.py:app

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

    restate-server

  5. 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.

  6. 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.