How performance metrics are calculated in a Content Delivery Network
With the evolution of Content Delivery Networks (CDN), web applications have evolved, and the browser retrieves content from a variety of servers.
A modern view of a web browsing experience
To calculate performance metrics, the system passively monitors your web traffic. However, if your web application uses a CDN, the system may need information from a browser to accurately calculate performance metrics.
BMC Real End User Experience Monitoring Software Edition enables you to set up monitoring for web applications with a CDN service.
A CDN is a large distributed system of servers deployed in multiple data centers in the Internet or on private networks. An origin server is where your web application content is stored, and it is monitored by BMC Real End User Experience Monitoring Software Edition.
Let's explore the loading of a page of a web application where some of the page components are served from a different web server than the container page.
Sample web page structure
Assuming that the system is monitoring only
www.acme.com and no other web server, it will treat Component 3 as the last component on the page, and will return an end-to-end time for the container, which is not the correct way of measuring. To deal with this deficiency, the system uses Edge instrumentation to provide a complete view of the page load. The only requirement is the system must see the container request.
The advantage of having the PRT available for a container page is that it is a more accurate measurement of the page's loading time than end-to-end time when there are components loaded but not seen by EUEM. This PRT can be used in a Watchpoint, a report, a dashlet, a Page SLT, and available in the export APIs. The disadvantage of relying on PRT is that there is no breakdown into latency sub-components such as network time, host time, idle time, SSL time and redirect time.