Http Requests Bitcoin Mining Pool?
One of the key aspects of a mining protocol is that the miners should be informed immediately when a new block is confirmed on the network. Otherwise, they will continue working on the old block which would then be useless work.

This is why there is not a simple GET/POST protocol for mining. The miners keep a connection open to the pool servers, so that there can be immediate two-way communication between them (from the miner for the case of a share completed, or from the server in the case of a new block).