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RFCx Core API - Tasks

Introduction

Core Tasks are background processes that listen to message queues for events and perform (potentially long-running) tasks when an event occurs. The motivation for tasks is to avoid blocking http requests to the API. Use cases:

• Send notifications to rangers when a chainsaw alert is created
• Create a thumbnail image when a new image is uploaded
• Find all the enabled classifiers for a stream and queue for processing when a segment is added to a stream

Running locally

1. Use docker-compose up -d to start the local SQS server (as well as the database).
2. Ensure the env_vars are set for MESSAGE_QUEUE_* (ENDPOINT should be localhost or your docker machine IP).
3. Run npm run dev:tasks to start the Tasks server (with hot-reloading).

Adding a new task

1. Define an event name in event-names.js
2. Publish to MessageQueue.default() when the event occurs
3. Create a new folder in the current directory for the task. Write a task handler to run when the event occurs.
4. Import the event name and the task handler in listen.js and add to the list of tasks.