How to handle responses from a slow external service?

Question

I have an interface for data processing (standard CRUD). I'm going to connect a new action which will send a set of URLs to a linkchecking service. These sets can be between 50 and 20,000 URLs and as such can take as much as 20 minutes to have a response ready.
The response will be a full list of pass/fail and response time for each URL.

1. What should I show the user when sending the request?
2. What should I show the user while the request is being processed?
3. How do I let the user know that it's completed?
4. I may need to put this step into a liner workflow (this would be step 3 out of 5). What do I do with the user while processing the links in the service?

Answer 1

The most important thing about your interface is not even how, but just the fact that something is happening during the waiting time. We all know systems where you press a button and then it says "Please wait" - and you don't know if you should still wait or if the thing has been stuck for half an hour. (To make a mockery of it, an animated GIF is then displayed that rotates enthusiastically while nothing else really happens…)

I would probably solve it like this: A single line that first displays "Request accepted", then while the requests are running "(1378/20000) Request www.example.org made, response in 130 ms". This can flicker; the important thing is that it actually shows the current task. If it hangs, it is immediately apparent exactly what it is doing. Finally, "(20000/20000) All requests processed", and in a new line the link "Download results as .csv file" and/or some statistics.

This is very easy to code, gives the user meaningful feedback and is useful in the event of an error.