streamer-go

Golang streaming library for Mevlink's tx streaming service. This library and the service itself is a pre-release; please contact us via mevlink.com and we'll be happy to debug any problems with you.

The streamer connects to a TCP socket on the lowest-latency Mevlink node and authenticates itself via HMAC challenge-response with your API key and ID. Here's such an example script:

package main

import (
	"encoding/hex"
	"log"
	"time"

	mlstreamer "github.com/mevlink/streamer-go"
	"golang.org/x/crypto/sha3"
)

func main() {
  var str = mlstreamer.NewStreamer("262c956a76c7009ab38cdba6302ec105", "14361648f02f8eab7ef5b48f1df58e8a")
  str.OnTransaction(func(txb []byte, noticed, propagated time.Time) {
    //Getting the transaction hash and printing the relevant times
    var hasher = sha3.NewLegacyKeccak256()
    hasher.Write(txb)
    var tx_hash = hasher.Sum(nil)

    log.Println("Got tx '" + hex.EncodeToString(tx_hash) + "'! Was noticed on ", noticed, "and sent on", propagated)
  })
  log.Fatal(str.Stream())
}

This library gives you a callback that three things:

• The full encoded RLP transaction bytes.
• The time at which the Mevlink node first learned of the transaction's existence (for example, via a NEW_POOLED_TRANSACTION_HASHES request)
• The time at which the Mevlink node sent the transaction to you over the TCP stream.

The binary streaming API is deliberately simple; if you are interested in learning how it works, feel free to read the comments. The ordering of the emitted fields, timing information, and MAC is such that you can choose to consider/respond to transactions before you have timing information or have verified the authentication signature.

The stream gives no guarantee of transactions being valid or will be successfully processed on-chain by BSC fullnodes; it simply provides transaction that have been seen via P2P node connections. Stay sharp, and verify what you need to.

On our immediate roadmap:

• Introduce a UDP socket to remove TCP performance/reordering issues.
• Add configuration options for receiving blocks, optional encryption, timing information.