Synthetic and Real User Monitoring Explained

Synthetic and Real User Monitoring Explained

Website monitoring solutions play a significant role in maintaining the performance, availability, and reliability of the digital world.

An ideal monitoring strategy allows you to understand precisely where to improve the website or application and how well it performs compared to your competitors. Most monitoring solutions provide either passive or active monitoring. Real user monitoring (RUM) is a passive monitoring approach, whereas synthetic monitoring is an active one. Here, we discuss how these differ and how the most robust monitoring strategy includes both RUM and synthetic.

Real user monitoring (RUM): Overview

Real user monitoring, also known as real user measurement, real user metrics, and end-user experience monitoring, tracks performance data from real users accessing your website or application. The performance data gathered from RUM is diverse because it captures the complex ways users actually navigate your apps. The end user could be using any combination of browser, ISP, or device in any location.

RUM is implemented by adding JavaScript tags to the application code. The script triggers when a user accesses the application and gathers data on various performance metrics, such as page load times and performance bottlenecks. This data, based on real user interactions, is relayed to the RUM platform, enabling you to analyze performance and understand real user behavior.

RUM is a form of passive monitoring that relies on services that observe the system in the background, tracking availability, reachability, responsiveness, and functionality. RUM data helps a business better understand its users by providing full visibility into application performance and identifying which areas of its site need optimization and focused attention. It can also provide a historic perspective, allowing you to determine performance trends over time.

Synthetic monitoring: Overview

An alternative approach to website monitoring is synthetic monitoring. This is an active monitoring method that, instead of collecting real user data, gathers performance data using agents that simulate real users. Synthetic testing is preconfigured for simulation, meaning the traffic is manually generated to monitor the performance of a website or application under a controlled set of variables, such as geography, network, device, or browser. 

Synthetic monitoring can be especially useful for measuring applications that experience low traffic or for identifying problems in less-commonly used geographies, networks, and browser types. You can use synthetic tests to replicate multiple user journeys, so potential performance issues can be identified before they affect the end user.

Synthetic testing may also be used to test websites and web applications in pre-production, so you can establish a baseline for performance and set appropriate alert thresholds once an application or website is live. Because synthetic monitoring does not require embedding code snippets in the application or website, users can analyze competitors’ performance by setting up monitoring for their websites and applications. This means you can benchmark your performance against major players in the industry.

Real user monitoring vs. synthetic monitoring

RUM and synthetic monitoring differ in how they are implemented and how they work, but both help track website and application performance in important ways. Both provide valuable insight into user behavior, network latency or bottlenecks, performance trends, and the overall health of the web application.

Both RUM and synthetic monitoring tools aim to improve application performance by providing insight into every step within the application delivery chain. Choosing only one monitoring type will not yield an ideal strategy. Synthetic and RUM complement each other. A comprehensive monitoring solution should include both monitoring types to get a 360-degree view of your website or application and help you ensure it is not only fast, reachable, and reliable, but also customized for the real needs of your end user.”

When evaluating the two monitoring types, you should first look at the value each adds to your monitoring strategy.

The benefits of synthetic monitoring

Synthetic monitoring allows you to:

• Simulate the user journey in a controlled environment
• Run tests at scheduled intervals (e.g., every 5 minutes) to proactively capture potential issues
• Build tests based on key business transactions (e.g., logging into an application service)
• Monitor complex transactions and processes (e.g., checking out a shopping cart)
• Test at every stage in the production lifecycle (e.g., User Acceptance Testing, Beta, GA)
• Exercise areas of the applications that receive a low amount of live traffic
• Test reachability from less common geographies (e.g., South America) and networks (e.g., a wireless provider in Brazil)
• Analyze performance trends from the vantage point of various geographies

Synthetic monitoring helps you:

• Run 24/7 monitoring
• Reduce MTTR (Mean Time to Resolve) as the tests actively track application performance
• Receive alerts whenever there is a notable variation in performance metrics, including downtime
• Gather performance data in a pre-production environment in the absence of real user traffic (RUM is meant for use in a production environment)
• Benchmark your service against competitors
• Track service level agreement (SLA) breaches (e.g., ensure that your application loads in less than 5 seconds from any location in the world 99.999% of the time)
• Monitor the performance of third-party services, including using A/B testing

The benefits of RUM

RUM monitoring allows you to:

• Gather data from real end users across a variety of environments
• Collect diverse data for every user accessing the application
• Configure customized variables in JavaScript to track and collect custom application-specific data
• Monitor live user experience in real-time (e.g., the users currently active on your website)
• Record screenshots or filmstrips of experiences by real users on your website

RUM monitoring helps you:

• Capture real end-user experiences across devices, browsers, and geographic locations.
• Correlate user engagement and business KPIs with application performance
• Calculate conversion ratios based on user engagement metrics (e.g., what percentage of users clicked on a specific link)
• Utilize historical usage data to forecast web performance trends and business outcomes

What type of monitoring do you need?

Both RUM and synthetic monitoring tools aim to improve application performance by providing insight into every step within the application delivery chain. Choosing only one monitoring type will not yield an ideal strategy. Synthetic and RUM complement each other. A comprehensive monitoring solution should include both types of monitoring to provide a 360-degree view of your website or application and help ensure it is not only fast, reachable, and reliable, but also customized to the real needs of your end users.

How RUM and synthetic complement one another

The examples below illustrate three ways in which RUM and Synthetic complement one another.

Correlating business with performance

Synthetic monitoring can provide the performance data you need to analyze end-user experience, enabling you to pinpoint problems with page load time or network bottlenecks.

However, if you want to analyze exactly how web performance impacts business revenue, then you need more than synthetic performance metrics. Since RUM is generated by real user traffic, it provides essential insights into business metrics, such as conversion rates, which can then be correlated with continuous performance metrics collected from synthetic testing.

Identify problems before active users arrive

Global daily application usage shows cyclical patterns tied to when users are awake and active in each region. Applications hosted in public cloud environments are often replicated across multiple geographies (e.g., US, Europe, Asia) to reduce latency for end users. It is common for infrastructure maintenance to occur during off-peak hours, such as midnight in local time, which can cause occasional unforeseen application problems.

Synthetic monitoring is the most effective way to identify a configuration problem caused by an off-hours maintenance change, so it can be fixed before users begin using your application service in the early morning hours. On the other hand, RUM would be the most helpful tool for measuring application responsiveness for each and every live user during peak hours.

Testing applications in a staging environment

Since RUM collects data in real time as users access the application, it is not possible to use RUM data to gauge the performance of new features in a pre-production environment. In such a scenario, synthetic monitoring allows you to test the impact of changes to the application before they go live. RUM data is an added advantage here, as it provides real-world use cases for simulation with synthetic monitoring, enabling detailed testing in a staging environment.

Troubleshooting outages

Combining synthetic and RUM data can make troubleshooting quicker and easier. When synthetic tests fail or trigger an alert, data gathered from RUM will show you the real-time impact on end-user experience. Similarly, if RUM data reveals a performance anomaly, you can use synthetic data to replicate the issue by running the same transaction across multiple ISPs and geographic locations. Collecting data in this way allows you to triangulate from multiple vantage points to identify the root cause that may lie in the data path between end users and your application service. RUM and Synthetic can be used simultaneously to verify and conduct deep dives into performance issues.

Conclusion

RUM and synthetic monitoring provide different types of insight into how well your application performs. RUM helps you understand long-term trends based on usage patterns, while synthetic helps you consistently detect and troubleshoot short-term performance issues, even in the absence of real user traffic. Although using one or the other will help analyze performance in different ways, combining synthetic monitoring with RUM yields a more comprehensive and robust monitoring strategy that provides you with full visibility into your end users’ experience.

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