Browser Synthetic User Monitoring (Browser SUM) and Browser Real-User Monitoring (Browser RUM) both have the same goal of helping you improve your user's experience. The difference between the two is how they are used to accomplish this goal.
This page describes the monitoring differences, and how to use the two monitoring types together.
Identify Issues
Although Browser RUM can detect certain kinds of problems (like JavaScript exceptions), it cannot comprehensively test for functional correctness. For example, you may want to verify that your online store has reasonable prices a list of items. If your site is down entirely, then the JavaScript Agent will never be loaded, so errors or verifications will not be reported. Fortunately, Browser SUM will keep running, discover the error, alert you, and provide detailed information about the problem.
Control Environmental Factors
Performance analysis in Browser RUM is complicated by the wide range of hardware, browsers, operating systems, and networks with which users access your site. Browser SUM uses consistent hardware, software, and network configurations, so if you see deviations in performance, you can be fairly certain a problem exists.
Use Synthetic Metrics and Screenshots to Understand the User Experience
Browser SUM can collect certain data that Browser RUM cannot. For example, Browser SUM provides screenshots, which shows you the current situation. You can also use the Visually Complete and related metrics to understand how users experience page load time.
Browser RUM excels at capturing the full breadth of performance that your real users experience. Browser SUM gives you confidence that your key workflows are always working and performing.
Differences Between Synthetic and Browser RUM Metrics
Although Browser SUM and Browser RUM report similar metrics, you should be wary of comparing them because of these differences:
- Hardware
- Network connections
- Different browsers
- Browser caching is not present in synthetic sessions
If you see a sudden change in any of those metrics, however, you should compare the results of Browser SUM and Browser RUM to see if there is an existing problem.