But I disagree with XML and OOP. XML was necessary for the first web APIs we had (they were called SOAP, in case you wasn't a developer that time). And OOP is everything you do, it's a way to write code more clear and maintainable (just forget everything about the 'reuse your code' and 'speed you development', OOP isn't just about this).
OOP may be everything _you_ do, but it is not everything I do, and there are large vibrant software development communities using paradigms and tools that are not particularly object-oriented. Beware of making over-generalizations like this.
People were building systems that had APIs exposed via HTTP a long time before XML.
There were some fanciful things said in the past 15 years about both of these and others. Articles in Wired with apparently smart people bubbling with enthusiasm for the limitless potential. Even at the time I thought, fer gosh sakes, XML is an encoding. The really hard problems are still unsolved.
I still hear "we'll use XML" instead of concrete architectural plans, like it's a magic wand you wave over your project and all your dreams come true.
At least as good as code for Plone components can be. I heard it has improved a lot since I left Plone-land, but, when I worked with it, there was a required level of confusion in your code for it to work with all layers of Zope and Plone.
I assume UML diagrams can render very clean code for Django and Zope 3.