When displaying a performance graph (Reports->Graphs) what do Resolve, Connect, Processing and Transfer mean?
Resolve time : The resolution (translation) of your Domains name in milliseconds.
Connect time : The time required for the connection to your server.
Processing time : The processing time measured in milliseconds .
Transfer time : The time for the completion of data transmission.
Lets discuss further via an HTTP example. The HTTP monitor (which uses the CURL library) will perform the test and measure the time of four basic events of the process:
- Test starts, timer starts
- The checker tries to resolve the hostname by querying a name server. The duration of this is called Resolve time. (if an IP address is used instead of a hostname, the metric is 0 milliseconds)
- A low level network connection is established with the remote HTTP server. The duration of this task is called Connect time and basically represents the network latency plus the responsiveness of the targeted server.
- The HTTP request is sent and waits for the very first bytes of the result. That period is called Processing time, and represents how fast the targeted application handled the request. For example, a web application might need to access a database, do some calculations, and only then start sending the results back. This metric represents how fast the application stack responded to the request.
- The checker continues downloading the rest of the HTTP response data. The duration is called Transfer time.
Another metric, Download time, consists of Processing time + Transfer time. Download time represents the amount of time beginning immediately after the request has been sent until the whole response is downloaded.
The above calculations are also done in other monitor types such as FPM. On multi-step monitors such as JMeter and RBM, the metrics from each step are accumulated.
Note that with multistep monitors the time between the steps and any other "scripting overhead" is not included in the metrics. Instead, it is recorded as User Interaction time (think someone clicking on links, taking some time to type, then pressing submit. This is User Interaction time.