What happens after The Hague court rules?

For the past several weeks, the government had been expecting the Permanent Court of Arbitration at The Hague to rule in its favor on its dispute with China in the South China Sea.

Official sources looked forward to it as a watershed moment. But as this is written, the ruling was yet some hours away. What would it say is the core question, but even more critical is, what would China say or do?