This chapter described system, application, and model monitoring goals together with the existing monitoring solutions for Scala, and specifically Scalatra. Many metrics overlap with standard OS or Java monitoring, but we also discussed how to create application-specific metrics and health checks. We talked about a new emerging field of model monitoring in an ML application, where statistical models are subject to deterioration, health, and performance monitoring. I also touched on monitoring distributed systems, a topic that really deserves much more space, which unfortunately, I did not have.

This is the end of the book, but in no way is it the end of the journey. I am sure, new frameworks and applications are being written as we speak. Scala has been a pretty awesome and succinct development tool in my practice, with which I've been able to achieve results in hours instead of days, which is the case with more traditional tools, but it is yet to win the popular support, which I am pretty sure it. We just need to emphasize its advantages in the modern world of interactive analysis, complex data, and distributed processing.