RPC subscription

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RPC subscriptions require a full duplex connection. CKB offers such connections in the form of tcp (enable with rpc.tcp_listen_address configuration option) and websockets (enable with rpc.ws_listen_address).

tcp rpc subscription example:

telnet localhost 18114
> {"id": 2, "jsonrpc": "2.0", "method": "subscribe", "params": ["new_tip_header"]}
< {"jsonrpc":"2.0","result":0,"id":2}
< {"jsonrpc":"2.0","method":"subscribe","params":{"result":"...block header json...","subscription":0}}
< {"jsonrpc":"2.0","method":"subscribe","params":{"result":"...block header json...","subscription":0}}
< ...
> {"id": 2, "jsonrpc": "2.0", "method": "unsubscribe", "params": [0]}
< {"jsonrpc":"2.0","result":true,"id":2}

websocket rpc subscription example:

let socket = new WebSocket("ws://localhost:28114")

socket.onmessage = function(event) {
  console.log(`Data received from server: ${event.data}`);
}

socket.send(`{"id": 2, "jsonrpc": "2.0", "method": "subscribe", "params": ["new_tip_header"]}`)

socket.send(`{"id": 2, "jsonrpc": "2.0", "method": "unsubscribe", "params": [0]}`)