Amazon S3 Expiration Date Issues with expiration parameter for HTTP queries

Question

It's given in AWS Documentation that "All HTTP queries have an expiration parameter that allows you to set how long the query will be valid."

What does that actually mean when applied for a file. For a publicly accessible data object does this mean that the data object itself will not be valid anymore, or that the browser will simply re-cache the object after the expiration date. I am really confused what the statement means. 

What if I don't set an expiration date?

Answer 1

If you are referring to the signed urls for private data stored on Amazon S3,  If files are publicly accessible they can be accessed with a simple url to the file: eg http://s3.amazonaws.com/[bucket]/[key].

However, they can be set to private in which case you need to provide a signed url to access the file. 

 Also, for the file downloads, you'd probably create a new url for each request with the url set to expire only a day in advance to protect your data. However, this does not expire/delete/remove your data stored on S3. It only affects the url to the file. You can go ahead and generate as many urls with different expiry dates as you require.