In many ways, this is the most straightforward pattern covered in this book. A single entry point, whether it be an HTTP request, some event notification, or anything else supported on your cloud provider of choice, triggers multiple invocations of some other serverless function in parallel. What one gains in this architecture is parallelism and hence speed. Our first example is one which is easy to understand and which you can view as the Hello World of serverless architectures.
Imagine a system which takes an image and creates multiple versions of the original image with different sizes smaller than the original. How can this be solved at its simplest? Once a user uploads an image, our system notices the new image upload and, using a for loop, iterates and creates the various thumbnails. Some fictitious code to do this may look like...
