It is shaping up to be the biggest Facebook event ever, with 5,000 developers flying in from around the world.

They'll hear exciting news about the company's plans to advance on many fronts, from artificial intelligence to virtual reality.

They'll also get the chance to interact with the senior team, and to find out how they can profit from this very powerful platform.

That, at least, is the official view of Facebook's mostly-annual F8 developer conference.

And a couple of months ago, when the attendees were making their travel plans, that may have seemed believable.

Since then, however, the Cambridge Analytica scandal has broken.

Mark Zuckerberg has been (lightly) grilled in Washington, the co-founder of his firm's WhatsApp messaging service has announced he's to quit - reportedly over a separate data privacy clash - and, perhaps most significant for the developers attending F8, the rules which govern their access to Facebook have been tightened.

Growing anger

If you have a look at a Facebook developer forum online now, you will find the mood is fairly grim.