If we're going to remove the old web UI, I think the new web UI has
to have the same level of unit testing. We shouldn't go backwards in
terms of unit testing.
I take a look at TestNamenodeJspHelper / TestDatanodeJspHelper / TestClusterJspHelper. It seems to me that we can merge these tests with the unit tests on JMX.
If we are going to
remove this capability, we need to add some other command-line tools
to get the same functionality. These tools could use REST if we have
that, or JMX, but they need to exist before we can consider removing
the old UI.
This is a good point. Since all information are available through JMX, the easiest way to approach it is to write some scripts using Node.js. The architecture of the new Web UIs is ready for this.