Question

This image from Charles shows some pretty interesting information:

• Duration
• Request Duration
• Response Duration
• Latency

I’d like to better understand what these terms actually mean.

ie., How does Charles measure the request duration? (In the course of a HTTP transaction, this is the time from when-to-when?) Likewise for response.

Also, request + response != Duration. Is the remainder server-side processing time?

What is Latency a measure of here?

Answer 1

From the documentation:

• Request – the time spent sending (uploading) the request (dark blue)
• Latency – the time spent waiting for network latency or processing
  time on the server (mid blue)
• Response – the time spent receiving
  (downloading) the response (light blue)