There are several pieces of data that need to be persisted and that don't fit very well into the Datastore or similar storage systems, such as images and media files in general; these are usually big and their size impacts application costs and how they should be uploaded, stored, and served back when requested. In addition, sometimes we need to modify these contents on the server side and the operation can take a long time.
We will add some features to the Notes application that will raise these kinds of problems, and we will see how App Engine provides everything we need to face them effectively.
In this chapter, we will cover the following topics:
Adding a form to our application to let users upload images
Serving the files uploaded back to the clients
Transforming images with the Images service
Performing long jobs with the task queue
Scheduling tasks
Handling e-mail messages from our application