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GetParsedBdnFlashBlockStream

Name: GetParsedBdnFlashBlockStream

The GetParsedBdnFlashBlockStream stream provides low-latency access to newly produced Flashblocks on the Base network, parsed into protobuf format for immediate use. Flashblocks are pre-confirmation blocks available before they are finalized on-chain and may differ from the final canonical chain.

This is real-time WS/gRPC, parsed Flashblocks data stream.

This stream is available to Enterprise Elite and Ultra tier users.

Example: WebSocket using CLI

wscat -H "Authorization: <AUTH_HEADER>" \
  -c wss://base.blxrbdn.com:5005/ws \
  --wait 1000 \
  --execute '{"jsonrpc": "2.0", "id": 1, "method": "subscribe", "params": [  "GetParsedBdnFlashBlockStream", {} ]}'

Example: Test with grpcurl

grpcurl -H "Authorization: <AUTH_HEADER>" \
  -H "Content-Type: application/grpc" \
  -d '{}' \
  base.blxrbdn.com:443 \
  streamerapi.Api/GetParsedBdnFlashBlockStream

Example: Golang

package main

import (
	"encoding/json"
	"net/http"
	"net/url"

	streamerapi "github.com/bloXroute-Labs/base-streamer-proto/streamer_api"
	"github.com/gorilla/websocket"
	"github.com/rs/zerolog/log"
	"google.golang.org/protobuf/encoding/protojson"
)

const (
	BxAuthHeader = "PUT_YOUR_AUTH_HEADER"
)

type Params struct {
	Subscription string          `json:"subscription"`
	Result       json.RawMessage `json:"result"`
}

type Response struct {
	JsonRPC string `json:"jsonrpc"`
	Method  string `json:"method"`
	Params  Params `json:"params"`
}

func main() {
	u, err := url.Parse("wss://base.blxrbdn.com:5005/ws")
	if err != nil {
		log.Fatal().Err(err).Msg("Invalid WebSocket URL: ")
	}

	log.Info().Str("url", u.String()).Msg("Connecting...")
	conn, _, err := websocket.DefaultDialer.Dial(u.String(), http.Header{
		"Authorization": []string{BxAuthHeader},
	})
	if err != nil {
		log.Fatal().Err(err).Msg("WebSocket connection failed: ")
	}
	defer conn.Close()

	message := []byte(`{"jsonrpc": "2.0", "id": 1, "method": "subscribe", "params": [ "GetParsedBdnFlashBlockStream", {} ]}`)
	err = conn.WriteMessage(websocket.TextMessage, message)
	if err != nil {
		log.Fatal().Err(err).Msg("Error sending message: ")
	}

	log.Info().Msg("Connected! Listening for parsed bdn flashblocks...")
	for {
		msgType, msg, err := conn.ReadMessage()
		if err != nil {
			log.Error().Err(err).Msg("Read error: ")
			continue
		}

		if msgType != websocket.TextMessage {
			log.Error().Err(err).Int("msgType", msgType).Msg("Skipping non-text message: ")
			continue
		}

		var response *Response
		err = json.Unmarshal(msg, &response)
		if err != nil {
			log.Error().Err(err).Msg("Failed to unmarshal response: ")
			continue
		}

		if response.Params.Result == nil { // Expected for the first update
			log.Warn().Msg("parsedBdnFlashBlock is nil")
			continue
		}

		var parsedBdnFlashBlock streamerapi.GetParsedBdnFlashBlockStreamResponse
		err = protojson.Unmarshal(response.Params.Result, &parsedBdnFlashBlock)
		if err != nil {
			log.Error().Err(err).Msg("Failed to protojson unmarshal parsed bdn flashblock: ")
			continue
		}

		log.Info().Uint64("blockNumber", parsedBdnFlashBlock.Metadata.BlockNumber).Uint64("index", parsedBdnFlashBlock.Index).Msg("parsedBdnFlashBlock")
	}
}

Response (Flashblock Event)

  • Index 0 (with Base): Shows the Flashblock plus chain-level context (base).

  • Index 1–10 (without Base): Shows Flashblocks without repeating that extra context.

<<< {
    "jsonrpc": "2.0",
    "method": "subscribe",
    "params": {
        "subscription": "7e84d5e2-570b-4750-88c4-fe934ad93531",
        "result": {
            "payloadId": "0x039e03386af93ec4",
            "index": "0",
            "base": {
                "parentBeaconBlockRoot": "0x3f2b3d2be05b1aa421062640a52a8fb564c310a6608ee77028b54a4e534a44fd",
                "parentHash": "0xa373c39558c65f2f276de7c5ca24b92b42b86853d05e9cb4bacc3d28d9c3b5ac",
                "feeRecipient": "0x4200000000000000000000000000000000000011",
                "prevRandao": "0xe6e6e07efed22009d57c725011d98d65ae24d568620db7342fa8ae7c3426a8f5",
                "blockNumber": "0x20ba0f2",
                "gasLimit": "0x8f0d180",
                "timestamp": "0x68a19ec7",
                "extraData": "0x000000003200000003",
                "baseFeePerGas": "0x5b777"
            },
            "diff": {
                "stateRoot": "0x0000000000000000000000000000000000000000000000000000000000000000",
                "receiptsRoot": "0x4a27677b9a161f080a4bdce3a56e6dc7ead5ab900ec62f3c7151a519a45cf6be",
                "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
                "gasUsed": "0xb44c",
                "blockHash": "0x5a70134941f5e08c2b6e122042fefc399606f2e9f7911caed6881c06b3e04792",
                "transactions": [
                    "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"
                ],
                "withdrawals": [],
                "withdrawalsRoot": "0x871f79faec942df96cd90e26b473cb2afca8aee4858d5e2d3fae0c3a64e9ce62"
            },
            "metadata": {
                "blockNumber": "34316530",
                "newAccountBalances": {
                    "0x0000f90827f1c53a10cb7a02335b175320002935": "0x0",
                    "0x000f3df6d732807ef1319fb7b8bb8522d0beac02": "0x0",
                    "0x4200000000000000000000000000000000000015": "0x0",
                    "0xdeaddeaddeaddeaddeaddeaddeaddeaddead0001": "0x69076b18a41d8"
                },
                "receipts": {
                    "0x9cfb253a30c498111c6485638b279483c8e61419ee78be3251195c4f88055a02": {
                        "Deposit": {
                            "cumulativeGasUsed": "0xb44c",
                            "logs": [],
                            "status": "0x1",
                            "depositNonce": "0x20ba0f4",
                            "depositReceiptVersion": "0x1"
                        },
                        "Eip1559": null,
                        "Legacy": null
                    }
                }
            }
        }
    }
}
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