This post originally appeared on https://dynamicsnotes.com/latency-between-pos-and-retailserver/.
There is always going to be a physical separation between the server (RetailServer) and client (ModernPOS or CloudPOS browser instance). If this physical distance is large, every RetailServer call will incur a larger additional latency. There is no code change that can fix this, a redeployment of cloud or client components will be needed to lower the value.
Here is how to measure the latency.
- Find out what Azure data center the RetailServer is hosted. Use LCS environment page for the specific environment or ask your IT administrator. For example, my RetailServer is hosted on the Azure primary region “West Central US”.
- On the same computer as your store terminal open an internet browser window and browse to http://www.azurespeed.com/. Check at correct Azure region or a few on the same area. The web page will tell you the latency from your computer to the data center the RetailServer is hosted. It is very important to use the same computer as the store terminal, as sometimes customers use a dedicated network for the store terminals and a computer in the back office may be on a different network.
In my example, you can see I get a latency of about 41 ms (for every RetailServer call). That is a very good value (for this particular single store, it may have been better to use “West US 2” to get an even better response). Off course the choice should be balanced between all different stores that use this RetailServer instance.
If you want to further investigate where a latency issue occurs, you may use other networking utilities. For example tracert (http://www.mediacollege.com/internet/troubleshooter/traceroute.html). It will list all the routers it passes through until it reaches its destination, or fails to and is discarded. In addition to this, it will tell you how long each ‘hop’ from router to router takes.
Note that Azure does not seem to allow ICMP packets through, but tracert and ping can still be used to get a sense of what the issues are outside of the data center.
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