How to Access Binance Chain
Get Started pages already show how to access Binance Chain and DEX via Wallet and Explorers. Here we would like to dive into some technology details for access in a programming way.
There are 3 ways to read and write data from Binance chain:
Accelerated Node infrastructure provide easy access via http REST API and WebSocket
push APIs. There are mulitple endpoints from different validator infrastructures. Please
check the Web API Reference
There are public data seed nodes that joins the Binance Chain network. They usually provide RPC calls. Please check the Node RPC Reference.
You can also run a full node by yourself, so that you will have a local server to send RPC requests and read Chain information off.
Command Line Interface
Essentially command line interfaces are just tools that wrap the incoming command line arguments and call RPCs. Please check the Command Line Referenace.
You can only write to Binance Chain via
Transactions. Both Web API and Node RPC provide
broadcastTx API to submit a
signed and encoded transaction onto the Binance Chain. The detailed process is outlined below:
The transaction message and related information will be packed into
payload, which is the so called
The transaction body, memo, signature, etc. all fill in the
Standard Transaction, encode and then broadcast out together onto Binance Chain.
Encoding defines the way how transactions are serialized and transferred between clients and nodes, and different nodes themselves. here is a detailed specification on the transaction types and encoding logic.
Signature is the evidence to prove the sender owns the transaction. It will be created from the actions outlined below:
Compose a data structure. please note
dataare the same as in the above
chain_id: a string, unique ID for the Chain, it stays the same for most time, but may vary as Binance Chain evolves;
account_number: a string for a 64-bit integer, an identifier number associated with the signing address
sequence: a string for a a 64-bit integer, please check the below
memo: a string, a short sentence of remark for the transaction
msgs: a byte array, json encoded transaction messages, please check the encoding section.
source: a string for a 64 bits integer, which is an identifier for transaction incoming tools
data: byte array, reserved for future use
Encode the above data structure in json, with ordered key, Specifically:
- Maps have their keys sorted lexicographically
- Structs keys are marshalled in the order defined in the struct
Sign SHA256 of the encoded byte array, to create an ECDSA signature on curve Secp256k1 and serialize the
Sresult into a 64-byte array. (both
Sare encoded into 32-byte big endian integers, and then
Ris put into the first 32 bytes and
Sare put into the last 32 bytes of the byte array. In order to break
curve.Order() - Sif
S > curnve.Order()/2.)
signature will be encoded together with transaction message and sent as
payload to Binance Chain node via RPC or http REST API, as described in the above section.
Account and Sequence Number
Account is created, besides the balances,
Account also contains:
- Account Number: an internal identifier for the account
- Sequence Number: an ever-changing integer.
The Sequence Number is the way how Binance Chain prevents
Replay Attack (the idea is borrowed from Cosmos
network, but varies a bit in handling). Every transaction should have a new
Sequence Number increased by
1 from the current latest sequence number of the
Account, and after this transaction is recorded on the
block chain, the
Sequence Number will be set to the same number as the one of latest transaction.
This logic forces the client to be aware of the current
Sequence Number, either by reading from the
blockchain via API, or keep the counting locally by themselves. The recommended way is to keep
counting locally and re-synchronize from the blockchain periodically.
SDK in different languages are provided to simplify use of APIs to access Binance Chain.