REST API Design for Long-Running Tasks 🚀

Some operations in REST APIs take a long time to complete, such as processing large datasets, file uploads, or triggering complex workflows. Instead of making clients wait, we need a better approach to handle asynchronous processing.

In this guide, we will cover:
✔ What are Long-Running Tasks?
✔ Problems with Synchronous Requests
✔ Best Approaches for Handling Long-Running Tasks in REST APIs
✔ Implementing Asynchronous Processing in Spring Boot

Let’s get started! 🚀

🔹 What are Long-Running Tasks?

Long-running tasks are operations that take more than a few seconds to execute. Some examples include:

✅ Image Processing — Applying filters, resizing images.
✅ Large File Uploads — Handling multi-part uploads.
✅ Report Generation — Creating PDF/CSV reports.
✅ Machine Learning Tasks — Running AI/ML model inference.
✅ Data Migration & Background Jobs — Moving or transforming large amounts of data.

🔹 Problems with Synchronous Processing

A typical synchronous request-response cycle looks like this:

📌 Example Request:

POST /generate-report