Overview
APPM collects and displays Oracle Database historical and current performance related data.
It collects performance data such as wait events and active session history. Collected data is stored in central repository and used to identify and analyze performance issues like resource intensive SQL statements.
One of its key features is to conveniently display information required to identify performance issues root causes. It also allows to drill down on identified performance bottlenecks.
It offers similar functionality as Oracle ASH/AWR, but it also works on Standard and Express Editions.
APPM Repository

APPM Collector samples monitored database’s performance statistics and stores it in APPM Central Repository. Collection of samples has minimal performance impact on monitored databases. Repository database where samples are stored does not need any Oracle license.
APPM Collector can run on the same host as database or it can collect the samples via SQL*Net.
APPM Central Repository is based on docker containers and can run on any host that can run Docker Container. Usually, this is a dedicated virtual machine. It’s also possible to deploy it on Oracle Cloud.