WOW, 5 years of searching and finally I found what I've been looking for (because I could never find the time to develop, and so many projects out there were 'close' but not quite flexible enough).
I was actually about to write a new VP framework in Flex, but decided to conduct one more round of extensive search to be sure no-one had done the same - I found this, not Flex, but who cares as Eclipse integration is far more powerful, I'm stunned about both the capability of this tool, and how long it took me to find it! ;).
What's happened here from my point of view is that someone/somegroup implemented a truly workable visual + data flow programming framework with remarkable intelligence - function alongisde fantastic intuitive usability - by the way, this software also has so many uses even beyond web applications, which was the main additional acceptance criteria for me.
I've been theorising about, and have wanted to build for over 5 years, an automated testing framework; I envisaged a system where 'developer integrators' would customise a test tool to talk to Windows Forms / Java / Flex whatever, and the business-aware testers would simply click together the assets for performing actions based on truly reusable components.
My dream has arrived I think.
Absolutely amazing work.
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