Plone page request processing walkthrough
Plone guides lacked "big picture" view what's going inside Plone, so I decided to draw one. It's literally a big picture, 3000 x 12000 pixels.
The UML sequence diagram shows how HTTP request is processed and HTTP response formed. It cuts through application stack from HTTP server to TAL templates processing. This should help every developer diving into Plone internals.
I cheated a bit at the right edge of the diagram with Schema, Field and Widget processing. Fields and widget instances are really extracted in base.pt phase, but the diagram would have become overwhelmingly complex without taking a shortcut to get these important elements included.
Some boxes and arrows are a bit off. This is because buggy Java Studio Entreprise 8 which few times destroyed my work and has some bugs in its layout engine. I don't recommend using JSE 8 for complex modelling like this due to modeller stability problems. I hope I can roll out a fixed version in the future. Most of the 8 hours working session actually went to fight against JSE 8 instead of productive work.
Java Studio Entreprise project files are also attached if someone wants to edit the diagram.