# Subscribe to all 1 minute book summaries for all assets on all exchanges
ws.send({action: 'subscribe', channel: ['book_snapshots']})
# Subscribe to Deribit's BTC-PERPETUAL instrument, top 5 levels, updated every 100ms
ws.send({action: 'subscribe', channel: ['deribit.BTC-PERPETUAL.book_snapshot_5_100ms']})
# Subscribe to Bitmex's XBTUSD instrument, best bid and ask, updated on every change
ws.send({action: 'subscribe', channel: ['bitmex.XBTUSD.book_snapshot_1_0ms']}
# Subscribe to book deltas for Deribit's BTC-PERPETUAL
ws.send({action: 'subscribe', channel: ['deribit.BTC-PERPETUAL.book_change']})
# Subscribe to the combined, fee-adjusted orderbook for BTCUSD across all exchanges
ws.send({action: 'subscribe', channel: ['BTCUSD perpetual.combined_orderbook']})