When using Application Performance Monitoring, you're able to monitor key app performance metrics about the performance of a web application in production. APM is often thought of as a 'second wave' of performance monitoring techniques, which was preceded by traditional host-based monitoring. Let's dive in more.

Host-based monitoring focuses on indicators such as:

• Storage
• Memory
• CPU
• Network utilization

Application monitoring goes a step further and focuses on the actual "end-user" metrics of an application in real-time such as:

• Code-level errors
• Slowdowns in response times
• Error rates

How does this APM magic work?

There are multiple different ways Application Performance Monitoring tools can function. Let's look at the most common ways APM is used.

• An agent process that is deployed alongside a web application that hooks into the application runtime to collect telemetry data from the process
• Specialized web appliances that inspect Layer 7 traffic to generate telemetry

When combined with the monitoring mechanism, an external application generates synthetic traffic which is then sent to the application to monitor performance at predefined throughput intervals. When looking at APM tools and other monitoring types, the main difference to highlight is that the telemetry data is generated by inspecting the application runtime, and the performance metrics that it exposes.

Can APM help me?

Traditional host monitoring can make you feel stuck with no step closer to an answer. Application Performance Monitoring is designed to answer questions that you can't get an answer to. While understanding the raw resource utilization of your application is useful, it doesn't give you a lot of information when you're trying to track down why a specific request has high latency, why a particular transaction against your database is failing, or how your application performs under load.

Let's take a look at common questions asked on a daily basis.

• What are the implications of this issue on user experience for end-users?
• Where is this high latency coming from?
• What caused that outage?
• Why are we getting an error here?
• Why is this transaction failing?
• Can we find the root cause of this substandard user experience?

Have you asked yourself these questions before? If you're nodding your head furiously, you can look to APM to provide the answer.

Monitoring vs. Management: What's the difference?

Application Performance Management applies to a suite of applications while Application Performance Monitoring applies to a single application. An application performance management tool is able to aggregate and compare multiple types of metrics across multiple applications and services in order to pinpoint performance issues and regressions in your suite of applications. On the other hand, Application Performance Monitoring looks at the code-level to ensure each step is monitored thoroughly.

Is Network Monitoring different?

Network monitoring focuses on routers in order to detect issues with an application or collecting telemetry from network devices such as switches. If you're looking to get a complete picture, networking monitoring requires stitching together information from each line. This approach doesn't provide sufficient resolution or information for modern applications, however, especially when the application itself may be running behind a variety of proxies or service routers which themselves are running on virtualized networking equipment.

APM vs. Observability: What's the difference?

You've heard the hype of observability, but how is it different from APM? Observability, sometimes confused with Opentelemetry, is a holistic approach to fully understanding your application performance as well as a shared set of practices and terminology to help communicate performance across your organization. While observability helps you navigate from effect to cause, APM falls short of being able to answer "unknown unknowns," questions that you didn't think to ask ahead of time. This is the reason behind APM currently being eclipsed by observability.

Observability is unique due to the capability of answering questions about modern, microservice-based application architectures where you will often contend with serverless components, polyglot services, and container-based deployments running on Kubernetes. Circling back, observability provides a shared language to standardize communication around performance. This way you're able to focus on the measurement of service level objectives and service level indicators that are more broadly applicable and interpretable to your unique application architecture than simple throughput or health checks.

Is Application Performance Monitoring worth it?

Instead of depending on the second or third order metrics about host or network utilization to understand your application's performance, APM collects real-time performance data from the perspective of an end-user. Another bonus: real-time results of database queries and page load times are provided with APM in a way that's not possible with host-based monitoring. This information can be invaluable in understanding how your application performs under load or while trying to track down bugs in your software. APM solutions provide alerting systems to IT Operations, Site Reliability Engineers, DevOps, and more to quickly troubleshoot performance issues and slowdowns.