protected void onConnect(ClickHouseConfig config, SocketChannel channel) throws IOException {
        if (channel.finishConnect()) {
            log.debug("Connection established: [%s] <-> [%s]", localAddress(), remoteAddress());
            setInterestOp(SelectionKey.OP_READ);
        } else {
            throw new ConnectException(ClickHouseUtils.format("Failed to connect to [%s]", remoteAddress()));
        }
    }
Reads raw request from the input stream.
clickhouse-client/src/main/java/com/clickhouse/client/AbstractSocketClient.java