One of the first changes we need to do in order to scale an application is to make the environment where it runs more flexible to accommodate the necessary changes, which usually involves creating WebLogic components such as clusters, servers, and machines. In order to interact with multiple (remote) machines, it's recommended that you set up the WebLogic Node Manager process. The Node Manager is a small Java process that runs standalone and can perform basic operations on WebLogic Server instances like start, stop, and restart.
Until Version 12.1.1, you could have only one Node Manager running on a specific machine and all requests to start or stop Managed Server applications from different domains were sent to it. The concept is really nice, having just one component running to deal with all resources available on that machine. But things would usually get tangled and this topology proved hard to maintain; for instance, different domains are managed by different...