Very large HTTP request vs many small requests

Question

I need a 2D array (as Json) to be sent from server to client. It would be around 400x400 in size with each entry around 4 characters of text. So that makes it around 640KB of data.

Which of the following extreme approaches is better ?

1. I make a large HTTP request of all the data at one go.
2. I make 400 requests - each asking for a single row (around 1.6 KB)

I believe optimal approach would be somewhere in middle. Could anyone give me an idea what might be the optimal single request size for this data?

Thanks.

Answer 1

Couple of considerations for choosing one big vs several small:

• In the single request case, you can't do progressive data processing as the data arrives; you need to wait for the full packet to arrive before you can do anything. If it fails, you need to start everything from scratch.
• In the multiple requests case, you can do progressive data processing. However, you now have to consider the potential for multiple failures and how to recover from these.
• Multiple requests incur overhead for each request. This is additional bandwidth you app will be consuming.
• Some HTTP agents limit the number of concurrent requests to the same server, and you might need to do some logic to work around that.
• Response compression will work better for the single request case.
• Multiple requests won't require you to allocate the full memory for your data. Granted, 640KB is not that big chunk of memory, so that might not be a big consideration for you, depending on how often you will allocate it.
• In the case of early terminate of the process (either a Cancel button or the app is terminated or the browser navigates away from your page), the single request will still finish the full response download; however, for the multiple requests case, any request your code hasn't started yet will not be executed.

Honestly, I wouldn't be that worried about the last two and would base my choice on 1) is progressive data processing important; and 2) what your app tolerance is for failures and partial data.