Ping_AWS: ping aws server and get the closet server.
Async_Html: html call asynchronously.
Remote_Script_Call: html call to run a script in flask server.
Simple_Grpc: a simple grpc server with rocksdb.
Operation_Sync: grpc server/learder database is sync with a client/slave database by client reading operation history from the server.
Grpc_Node: a fault tolerant grpc node that can put/delete/forward request from other nodes while in sync with its inner nodes.